My guys who work on my car tell me that a roots type supercharger is almost ready to be realsed, price is unknown yet i will post price, boost is a lil upseting, were looking at about 8 to 9 psi, but Great for our Low End Problems :) www.Smokinjoeracing.net, if you live in the N.Y long island Area these guyz are the best out there.

Well, keep us posted. 8-9 Lbs of boost is actually higher than most kits under development. Also, any idea on prices?

No idea on prices, soon as i have them i will post them, what other kits are under devolpment?

Quite a few, but the ones I can recall are from Greddy/Trust, Blitz, ATI/Procharger, Boost Solutions, and SSR Engineering (almost complete).

Have they all been Superchargers or some turbo kits, Cuz i havent found any turbos, and are the other kits Roots,Centifical, or screw type?

Spend some time reading here in this forum... they're all written up here. All are turbo kits except the ATI/Procharger.

Is there any advantage to using a roots, versus a screw type supercharger? It almost seems like you've got all the benefits of a roots without any of the disadvantages.

Bottom Line Best Super Charger is a Centrifical Supercharger, a Screw Type is Mainly used for Trucks and gets the back burner on this one, Roots and Centrifical are the best, Centrifical puts out more boost more on the lines to 17 18 psi, and Has to Blow off

Roots Gives Boost mainly in low Rpm range, which would help our 8's of the line, all i kno is i need some serious stuff done cuz im losin to alot of people out there wit jus my exhaust and Intake

A roots is a screw type. The differences between a screw type and an eaton type are only minor but they are essentially the same. Both are positive displacement but neither are centrifugal type. A centrifugal blower is basically a crank driven turbo the roots/eaton gives more low end response because it is almost always running at full boost.
The advantages are: almost full boost from idle to redline
The disadvantages are the adiabatic efficiency i.e. heat generation and difficulty intercooling.

Roots/eaton gives about the same boost from idle to redline so you get almost the same power curve, just fatter all over. I think an intercooled roots/eaton is just what this and every car needs. More power under the curve!!

Originally posted by RoTaryStYleZ
Bottom Line Best Super Charger is a Centrifical Supercharger, a Screw Type is Mainly used for Trucks and gets the back burner on this one, Roots and Centrifical are the best, Centrifical puts out more boost more on the lines to 17 18 psi, and Has to Blow off

You're kidding right???

The twin screw supercharger was a factory option on the Mazda Millenia S and is standard on the new Ford GT. Used mainly for trucks huh? I can't think of a single truck that uses one. It is much more thermally efficient than the roots style and nearly as good as a centrifugal. It can also make the same amount of high end boost as a centrifugal without any low speed boost issues. It is also capable of faster low end boost response than a roots supercharger. It's #1 in my book. Centrifugal comes in last to me and here's why.

Centrifugal the best? It is the easiest to install in an engine bay and the most thermally efficient. I'll give it that. Needs to blow off? You don't mean this in the standpoint of a turbocharger wastegate to control boost but rather as a blow off valve. This is only determined by the location of the throttleplate after the supercharger. This would apply to any form of forced induction placed before this point. What good is the high thermal efficiency if it can't make very good boost anywhere other than redline? Suddenly it is making less power throughout the usable rpm range.

Here's how to figure out how much boost one is making based on rpm. Boost rises at a rate of the square of the supercharger shaft speed. What the hell does that mean? Think of atmospheric pressure as being 14.7 psi. This is what it is on a perfect day. Any boost that is added in to the system is added in addition to this. We just start counting at 0 when we should start at 14.7. OK here we go. Let's say we have a centrifugal supercharger designed to run at 8 psi (14.7+8=22.7 psi) at 8000 rpm. If we take the total psi (22.7) and divide it by static pressure (14.7) we get a ratio of 1.54:1 over atmosheric pressure. I'll keep this easy and figure out pressure at 4000 rpm. Take the square root of 1.54 which is 1.24 and multiply it imes 14.7. This gives us 18.24. Now take 18.24 and subtract 14.7 and we get 3.54 psi of boost at 4000 rpm. That sucks!!! At 2000 rpm we only have 1.6 psi of boost. For a roots supercharger that is set for 8 psi of boost we are typically at 100% pumping efficiency by 1/3 of the peak target rpm. This means 8 psi of boost by 2640 rpm vs the centrifugal with it's 2 psi of boost at this point. What good is the efficiency advantage now? Since the centrifugal has greater thermal efficiency and less pumping loss, it probably has the advantage at around 6.5 psi as compared to the roots style at 8 psi. This would be somewhere around 7000 rpm. If our powerband lasts from 6000-8000 rpm, it is the average power that matters most as far as speed is concerned. The roots would average a full 8 psi of boost while the average boost level for the centrifugal would only be around 6.5 psi or so. That means that both of these cars should be nearly identical in speed on the top end. The roots supercharged car however has far more low end power and could accelerate to these higher rpms much faster. This only means one thing in a race. For street use the roots also gives more low end which makes it much more fun and easier to drive on the street.

This example is really best at lower boost levels. At higher levels the efficiency difference starts to get greater and greater and favors the centrifugal. For street use though, I don't know why anyone wants one. I can't think of one class of race car that uses a centrifugal supercharger either.

If you keep losing races, race slower cars!

TRD Tacoma and Tundra (I think) uses screw type S/C. I think there are other trucks that do so too.

Even if that is true, that doesn't mean that they are the best only for trucks. Most factory superchargers have been Eaton roots style superchargers. Eaton has also just recently acquired rights to build and sell twin screw types though and this is what they will be replacing the older roots units with over time.

Originally posted by Omicron
Spend some time reading here in this forum... they're all written up here. All are turbo kits except the ATI/Procharger.

And Blitz and Kinght Sports.

Originally posted by Xyntax
TRD Tacoma and Tundra (I think) uses screw type S/C. I think there are other trucks that do so too.

Um... Ford Mustang Cobra (inaddtion to RG's mentioned Ford GT). Doesn't TRD offer other bolt-on S/C for other cars...Celicas and MR-S (MR-2 Spyder)?? GM uses a S/C on the Grand Prix engine... which has been shared across many model lines. Saleen bolts up an eaton S/C to the Windsor 351cid V8 that they drop into their top model Mustang as well have having S/C solutions for the OHC engines. BMW uses it in the Mini Cooper. 'nuff said.

Originally posted by Japan8
Um... Ford Mustang Cobra (inaddtion to RG's mentioned Ford GT). Doesn't TRD offer other bolt-on S/C for other cars...Celicas and MR-S (MR-2 Spyder)?? GM uses a S/C on the Grand Prix engine... which has been shared across many model lines. Saleen bolts up an eaton S/C to the Windsor 351cid V8 that they drop into their top model Mustang as well have having S/C solutions for the OHC engines. BMW uses it in the Mini Cooper. 'nuff said.


umm.. you forgot to read thatthe post. He was talking about SCREW type super chargers, not everything you just named. (everything you just named is most likely ROOTS type superchargers.)

umm.. to stick with the show-off'ed ness...


"'nuff said".

Mercedes also uses screw type SC's in their cars.

Originally posted by lafrad
umm.. you forgot to read thatthe post. He was talking about SCREW type super chargers, not everything you just named. (everything you just named is most likely ROOTS type superchargers.)

umm.. to stick with the show-off'ed ness...


"'nuff said".

Yeah... I read the post. Ford seems to use an Eaton supercharger in most applications and I'm pretty sure the GM supercharged 3.8L V6 is Eaton. I know the discussion was screw-type... but it was screw-type vs centrifugal. Was it not? I just expanded it to positive displacement vs centrifugal. Which Fords do and do not... I don't know off the top of my head, and I have better things to do than look it up... and I did specifically mention that the Saleen S/C was Eaton, and I've just said the same for GM (which I mentioned in my earlier post). The TRD S/C is eaton too.

AND if you actually take a look at an Eaton (modified-roots) S/C and a whipple (twin screw), you'd know that there is really little difference between them. The Eaton uses two similar twisted roots 3 sided rotors where as a Whipple uses twin screws... male and female.

slower cars????, I shoudnt Have 2, this Car was majorly under powerd and its needs some major fkin tuning, to kno that the new neon can beat you is ridiculous

Originally posted by RoTaryStYleZ
slower cars????, I shoudnt Have 2, this Car was majorly under powerd and its needs some major fkin tuning, to kno that the new neon can beat you is ridiculous
you bought this car as a drag racing car? Like the new neon was designed for?

Man.. you purchased the wrong car. you should go get a GTO or something if you want to be going fast in a straight line...

Totally Wrong, ive seen rotarys kick ass on drag strps, wat am sayin is the car was not tuned to kick ass out of the Factory

those rotaries were turbocharged and uber-strong. this is an N/A sports car.

Exactly, so that's wat we do to these, the engine has large amounts of potential, they just left it up to us to tune it, these other cars are almost tuned to theri max out of the factory

do superchargers drink alot of gas or just compress the air with the same amount of gas usage? Are we taking 10 mpg after installing one of these?

once the supercharger is under the hood then well be able to keep up

question, are any sites showing there rx-8 super chargers in production? or any sites with Specs? Boost Solutions etc..?? have nothing listed

Fuel economy under heavy throttle use will be significantly worse, fuel econonmy udner light load, i.e. normal driving and cruising without driving fast you will see a slight mpg loss, 1-4 gallons. Because boosted cars make a lot more heat, A/F rations have to be a lot more rich so being under boost you lose even more fuel.

Originally posted by Omicron
Quite a few, but the ones I can recall are from Greddy/Trust, Blitz, ATI/Procharger, Boost Solutions, and SSR Engineering (almost complete).

i spoke to SSR-Engineering the other day and they said that they are going to work on their turbo kit and finished that first and that plans for a S/C are far down the road for them. possibly a year

Originally posted by Icemastr
Fuel economy under heavy throttle use will be significantly worse, fuel econonmy udner light load, i.e. normal driving and cruising without driving fast you will see a slight mpg loss, 1-4 gallons. Because boosted cars make a lot more heat, A/F rations have to be a lot more rich so being under boost you lose even more fuel.

There is no reason to have any worse fuel mileage on a stock motor in an off boost situation unless you have poor tuning or too large of an injector. The problem is no one who goes with forced induction drives this way!

Bltiz is working on a screw setup for the RX8 similar to what they have done on the Celica. Rotarygod already summed it up, but I see no reason to go with a roots over a screw except in a low boost situation where there is a cost factor and little power gain is expected. Does a whipple even cost more than an eaton?

I don't know for sure, but I suspect yes... a Whipple is slightly more expensive than Eaton. According to literature and application, Eaton seems to be a decent performer as well. Remember an Eaton is more like a hybrid between roots and screw-type.

Ssr says there turbo will be ready in November, is this the soonest well get some boost, anyone one know if anything else is coming out earlier??

Dude... plenty has been discussed already... Greddy, Blitz, SSR, another turbo under development, other S/C kits under development, NOS... Do a search.

A Roots type supercharger (Eaton) is not at all similar to screw type (aka Lysholm) superchargers made by Whipple, Opcon, etc. Even a Roots supercharger with twisted lobes is totally unlike a Lysholm. A Roots supercharger uses external compression versus the internal compression of a Lysholm. Thermodynamically this is a huge difference.

I'm no mechanical engineer, but...

" To make the Roots type more efficient, Eaton has modified the impellers by adding a twist to them and moving the intake port to the end. This makes them more efficient and quieter. This is called a "Modified Roots" type supercharger. This is the type used in the TRD Supercharger kit. The biggest difference between the modified roots type and the Lysholm supercharger is that the modified roots type has two impellers that are same, where the Lysholm uses two dissimilar ones, a male and a female rotor." - http://www.gadgetonline.com/Super.htm#How%20a%20supercharger%20works:

"The Eaton supercharger is essentially a Roots blower pump, with one substantial design wrinkle; each rotor has been twisted 60 degrees to form a helix. The two counter rotating rotors have three lobes, which intermesh during operation. These twisted rotors, along with specially designed inlet and outlet port geometry, help to reduce pressure variations resulting in a smooth discharge of air and a low level of noise during operation. This arrangement also improves efficiency over traditional Roots superchargers. With helical rotors and an axial inlet the Eaton supercharger can be spun to up to 14,000 rpm, thereby reducing package size. " - http://www.automotive.eaton.com/product/engine_controls/whysuperchargers.html

"The original designs used straight lobes running the length of each rotor, with air induction coming from a whole at the top of the unit. They also had loose internal tolerances that hurt performance and efficiency, as well as creating excess heat from friction. Some of these old designs had typical thermal efficiencies below 60% (called adiabatic efficienc,: the ability of an air pump to come as close to ideal in terms of pumping performance as possible), putting them at the bottom of the scale in terms of supercharger efficiency. More modern designs first added a third lobe to each rotor, then twisted them axially for greater efficiency and less noise. Advances have also been made in how air flows through the housing, with modern designs pulling air in from the rear of the unit, and pumping it through carefully designed outlets for increased performance. Internal tolerances have also been improved greatly, and better lubrication/sealing of the units has become commonplace. Eaton Corp. has nearly perfected the originally inefficient design, to the point that it’s thermal efficiency is the best in the business, and nearly on par with other designs... LYSHOLM COMPRESSORS...Also called screw compressors, these offer all the advantages of roots type blowers and then some. This design’s pros and cons are very similar to Roots s/c’s, with one major difference; efficiency. Typically these compressors have peak adiabatic efficiency at or above centrifugal designs.
Externally these look nearly identical to the current Eaton design, but internally they do have some differences. The main difference between roots and lysholm compressors is in how the two rotors interract in the supercharger housing; being that the roots rotors really don’t. Lysholm compressors have the familiar two rotor, twisted lobe design, but each usually has 4 lobes instead of 2 or 3, and each rotor’s lobes have their own specific shape. One rotor will have thin blade style lobes with a fat ridge on top, while the other will have fat teardrop shaped lobes with a sharp edge. As the two rotors spin, the lobes interlock to form nearly airtight sections within the supercharger housing. This interlocking and sealing action is where the design gets it’s advantages over roots blowers, being better thermal efficiency and much improved high pressure boost performance..." - http://www.automotiveforums.com/t425.html

It looks to me like Eaton IS very similar to a Lysholm. The design differing essential in rotor design, with the Lysholm being the more efficient of the two.

Your explanation of internal and external compression, doesn't seem to fit with what everyone else has to say. They say that the Lysholm is more efficient, particularly at high boost/pressure levels because the rotor design seals better than a roots or eaton supercharger does. The air that gets lost because of the weaker sealing is what gives the roots supercharger it's low efficiency. Doesn't sound like external or internal compression to me.

http://www.magnacharger.com/

http://www.newdimensions.com/super_20.html

http://www.whipplesuperchargers.com/content.asp?PageID=68
(notice that Eaton isn't mentioned... could it be because their advantage isn't so clear and strong then... hmmm)

http://www.procharger.com/tech.shtml
http://www.procharger.com/intercooled.shtml

Just to throw a kink in this whole confusion, Eaton is now making twin screw superchargers. Who do you think makes the Ford GT unit?

Here is an end diagram of a roots style Eaton supercharger. The roots can have 2 or 3 lobes. This one has 3. The traditional roots blowers also have straight rotors. The Eaton has a twist in theirs over the length of 30 degrees. Their race units have a twist of 60 degrees. Air comes in and is sent around the outside edge of the housing to the other side. This is a little different than the twin screw. The tolerances in this picture are highly exagerrated.

Here is a diagram of a twin screw unit. You can see the immediate difference between the rotor shapes of the roots vs the twin screw. The tolerances are much tighter on the twin screw. Air also does travel around the outside edge of the case but it moves differently. The air also moves forward along the length of the case simultaneously as it moves down and around. During it's path, the available area for the air to travel through gets smaller. This causes the air to get compressed. The roots and the twin screw are similar in that they are both positive displacement units that use rotors and are around the same size. The principle of how air moves through them is completely different though.

rotarygod, sorry but... The moddified-roots Eaton S/C doesn't flow air exactly as you described. The description you gave was for a traditional roots S/C. In the Eaton moddified-roots S/C, the intake has been moved to the rear and the outlet has been designed to reduce pressure variations. This has the effect of increasing the efficiency of the S/C over tradition roots.

Did a Search, Only thing found still is ssr's turbo, does anyone have a link to any other sites??

Originally posted by Japan8
I'm no mechanical engineer, but...[B]I play one on TV[B]

It looks to me like Eaton IS very similar to a Lysholm. The design differing essential in rotor design, with the Lysholm being the more efficient of the two.

Your explanation of internal and external compression, doesn't seem to fit with what everyone else has to say. They say that the Lysholm is more efficient, particularly at high boost/pressure levels because the rotor design seals better than a roots or eaton supercharger does. The air that gets lost because of the weaker sealing is what gives the roots supercharger it's low efficiency. Doesn't sound like external or internal compression to me.

Let me try and put it in different terms. A Lysholm compressor takes a fixed volume of air into an enclosed area and then shrinks the enclosed area. Kinda like bringing the ceiling down in an enclosed room. All of the compression in a Lysholm is accomplished between the rotors in a cavity that progressively shriks in volume. This is accomplished because the number of lobes is different by one from one rotor to the other with a corresponding change in pitch.

A Roots basically grabs a bunch of air from one room and throws it into another room. The new air smacks into the old air and their pressure increases. This is not as efficient because there are efficiency losses due to the acceleration.

When the lobes of a Roots are twisted the only thing that happens is the pressure pulses are smoothed out. This helps some with efficiency and noise.

Originally posted by babylou
Let me try and put it in different terms. A Lysholm compressor takes a fixed volume of air into an enclosed area and then shrinks the enclosed area. Kinda like bringing the ceiling down in an enclosed room. All of the compression in a Lysholm is accomplished between the rotors in a cavity that progressively shriks in volume. This is accomplished because the number of lobes is different by one from one rotor to the other with a corresponding change in pitch.

A Roots basically grabs a bunch of air from one room and throws it into another room. The new air smacks into the old air and their pressure increases. This is not as efficient because there are efficiency losses due to the acceleration.

When the lobes of a Roots are twisted the only thing that happens is the pressure pulses are smoothed out. This helps some with efficiency and noise.

Makes perfect sense. Thanks!

Originally posted by Japan8
rotarygod, sorry but... The moddified-roots Eaton S/C doesn't flow air exactly as you described. The description you gave was for a traditional roots S/C. In the Eaton moddified-roots S/C, the intake has been moved to the rear and the outlet has been designed to reduce pressure variations. This has the effect of increasing the efficiency of the S/C over tradition roots.

Sorry but... it does work the same. ;) The entrance is only different. Air gets sucked in from the back but gets thrown around the outside of the case. If air came in from the top it would still get thrown around the outside edge of the case. The diagram doesn't show intake locations because they are irrelevant as far as the way the air flow is concerned. Either way air still starts at the top of the case (either by getting sucked into the top from the back or directly on top) and then gets moved around the outside and out the bottom. Twin screw superchargers can also come in both configurations and Whipple has both options available. They didn't move the intake location for efficiency reasons. They did it for packaging reasons.

Damn RotaryGod, every time i think I know what I'm talking about you kick me in the nuts. I'm banning myself from the tech forums.

No shit newtlicious.

So rotarygod, they only efficiency changes effected by Eaton's changes to the roots design are from the twist added to the rotors? Intaking air from the rear or even front instead of the top of the rotors wouldn't have any effecton stablizing the air pressure inside? As you said the rotors are just tossing in coming air against the sides and out the bottom. Also looking at the direction of rotation of the rotors, you'd think that the relocation of the intake would have some beneficial effect (looking at your diagram the rotors would also push air back against the intake charge it seems... whereas the opposite direction would have avoided this problem). In the of the sites them mentioned the rotor design difference between roots/Eaton and lysholm... the two dis-similar ones of Lysholm creating a tighter seal which would allow it to handle greater pressure and with less losses than the roots/Eaton.

I ask all this because other than the twist to the rotors you seem to be saying that nothing else about the Eaton design improves efficiency and so it's only marginally better than a traditional roots blower. Am I misinterpreting you?

I think we have hope. Occasionally he is wrong, like about trucks. Like for example I believe the engine that is in the Ford GT is a Ford truck engine.

Actually Rotarian_SC, you are right and wrong. The 5.4L DOHC V8 in the Ford GT is related to the truck engine... but then so is the 4.6 SOHC in the Mustang GT and the 4.6 DOHC in the Cobra. They are Ford's "modular" engines. They are all essentially the same in design... just swapped the SOHC heads for DOHC, or change the bore. That's all. So it is the same in that sense... however, you are wrong in that the Ford GT uses an all aluminum (heads and block) engine, not cast iron like the trucks. Also the trucks are SOHC, not DOHC IF I remember correctly. And the tucks don't have the nifty supercharger we're discussing.... unless you're the F-150 Lightening...

Originally posted by Japan8
No shit newtlicious.

So rotarygod, they only efficiency changes effected by Eaton's changes to the roots design are from the twist added to the rotors? Intaking air from the rear or even front instead of the top of the rotors wouldn't have any effecton stablizing the air pressure inside? As you said the rotors are just tossing in coming air against the sides and out the bottom. Also looking at the direction of rotation of the rotors, you'd think that the relocation of the intake would have some beneficial effect (looking at your diagram the rotors would also push air back against the intake charge it seems... whereas the opposite direction would have avoided this problem). In the of the sites them mentioned the rotor design difference between roots/Eaton and lysholm... the two dis-similar ones of Lysholm creating a tighter seal which would allow it to handle greater pressure and with less losses than the roots/Eaton.

I ask all this because other than the twist to the rotors you seem to be saying that nothing else about the Eaton design improves efficiency and so it's only marginally better than a traditional roots blower. Am I misinterpreting you?

Nah, Eaton has other improvements to the Roots blower. The outlet shape triangular (at least the last one I had was) versus the usual rectangular. According to Eaton this shape has improved efficiency.

People keep saying the shape of the Roots versus the Lysholm rotors affords differences in clearances. I don't see why the shape would affect this. All of the Lysholms I am familiar with use machined rotors cut by a Weingartner or Linsinger mill which creates accurate shapes but they are quite expensive. Whereas the Roots uses extruded rotors which are not as accurate but are much lower cost. Is there something I am missing here?

Originally posted by Rotarian_SC
I think we have hope. Occasionally he is wrong, like about trucks. Like for example I believe the engine that is in the Ford GT is a Ford truck engine.

How was I wrong about trucks? The statement that was made was how twin screw superchargers are best suited for trucks (not engines from trucks installed in cars). That is false. You mention the possibility of a truck engine being used in a car. This would place the supercharger in a car not a truck. If a truck engine is used in a car, it is no longer a truck engine. It is a car engine. If I install a rotary in a truck, it becomes a truck engine. The GT engine is not just an engine out of one of their trucks. It may share a few of the same components, but that doesn't make it the same engine. If I had a kidney transplant and had one of my dad's kidneys, I wouldn't be my dad.

Eaton improved the efficiency of the older roots blowers by twisting the rotors and adding a 3rd lobe. This also had the benefit of quieting it down. Yes they did make some shape changes to the inlet and outlets that changed their efficiency but this doesn't mean that the blower still doesn't function the same way. Air still enters from the same general side of the blower case which is the top, travels around the outside edge, and exits the bottom. The principle has not changed. The Eaton blowers can actually be ported and improved upon even more. There are other things that have been done to make them more efficient. There is an aftermarket company that has installed light carbon fiber rotors with tighter tolerances. This makes less parasitic drag and doesn't heat up the air as much which in turn allows higher pressures to be run. The principle of how it works is still the same but the efficiency is increased. This is no different than what Eaton did with the original roots blower.

Damn Japan8, that was harsh. I wasn't that far off, Car magazines make the mistake of using the words "screw type", "Lysholm" and "Eaton" in the same sentence. These all fall under "screw type" as opposed to centrifugal type. I'm learning here too and I thought that taking a jab at myself might get a laugh out of someone. This "well one is twisted but the intake is at the front" stuff is great but we all have our specialties. I work in the aircraft field. You wanna discuss turbofan vs turbojet vs ramjet vs scramjet vs pulse jet, I'll go all day long but I'll never say "no sh!t Japan8" sorry I got my intake locations mixed up. All nit-picking aside, it all boils down to the difference between a positive displacemant blower and a centrifugal blower. The differences between whipple, eaton, Lysholm, Roots and twin screw are fairly minor. The differences between those and centrifugal types are great.

Actually newtlicious, I meant that to mean "Oh boy did he do me up... looks like I was mistaken..."

My bad dude. Jeez, I'm starting to act like I got a hole in my crotch or something. Must be my time of the month.

Originally posted by Japan8
And the tucks don't have the nifty supercharger we're discussing.... unless you're the F-150 Lightening...

Yes that is originally what I intended, the 150 Lightning engine, which I do believe uses a screw s/c like the GT.

Rotary God, from my understanding, this Lightning engine and the GT engine are pretty close to being similar. That is what I found ironic in your post about how "The twin screw supercharger was a factory option on the Mazda Millenia S and is standard on the new Ford GT. Used mainly for trucks huh? I can't think of a single truck that uses one". I am sorry, I wasn't quite trying to say wrong, but instead sometimes we can be able to be correct or inform you, which is meant to be taken as a compliment. I don't dispute your position on the screw vs. roots type s/c. I have no doubt that your automotive knowledge is much more vast than mine.

Just to set a few things straight the Lightning uses a roots style blower like the new cobra does, its practially the only SC car manufactures use, with a few exceptions from Toyota and Mazda. Whipples, Twin Screws etc are by far one of the best blowers, they are capable of up to "turbo" like HP but with all the advantages of the low end and always boosting characteristics we love (not capable of 24+ psi in most applications, but at similar boost levels they make turbo like HP numbers). The Navigator uses the DOHC 5.4L at 300HP, but after that the motors are about 80% different, Ford really went through that puppy to handle more power than its putting out, (read a HOTROD back issue, they went through a build up on one)
TRD also uses the roots style blowers for their Celica, Tacoma etc kits.

Rotarian_SC: I wasn't being defensive or hostile. I apologize for coming off that way. We're all friends here.

Haven't seen any posts about it but they had a proto type Supercharged RX-8 at the Rotary Revolution in Indy. Forgot to bring my camara I would have posted pix. They would not run it at the events said it was still not completely developed and didn't want any posted numbers out there yet. It was all stock brand new still had window sticker from Sunflower Mazda. Tech onhand to answer questions said expected to retail under $5,000.00 About 6 PSI Intercooler right behind front spoiler opening, Supercharger itself replaced airbox. Very slick professional install, needed aftermarket exhaust big time sounded like a golf cart driving around the parking lot. No sound but the quiet supercharger wine. Said the air fuel was controlled by a modified Canzoomer Stage One and expected the rear wheel hp to be up between 30 to 40 % Said they are hoping to get a deal finalized with Sunflower Mazda to do the install and even offer it as a warrentied option in the next year or so once they prove reliability.

Sunflower has been extensively discussed here. Just search for it. There's pics as well as a ton of info on the car/warranty/kits.

Just Talked to SSR, Turbo Kit will Be Realsed In a week or 2, they have posted some pictures on there website, check it out. Guy said there finishing the Dynos and then it will be ready. price still TBA but this guy said it will be around 5 G's

Just to mention it ... the Koenigsegg CC8S uses a 4.7l supercharged v8 ... it uses a centrifugal supercharger

it tops out at 650 hp or something but doesnt accellerate as quickly as the screw type supercharged supercars, SLR, Ford GT, or even the NA supercars with similar peak power ... 617hp Carrera GT is .7 or so seconds faster 0-60; I think the Carrera GT even weighs slightly more.

Just goes to show what kind of performance you get out of a centrifugal supercharger.

That car does 0-62 mph in 3.5 secs, the standing quarter mile in 10 seconds flat and tops out at 240 mph. That's pretty damn impressive. While I am a fan of positive displacement superchargers, neither the Ford GT nor the SLR are going to catch this car.

http://www.classicdriver.de/uk/magazine/3100.asp?id=11867

Originally posted by babylou
...All of the Lysholms I am familiar with use machined rotors cut by a Weingartner or Linsinger mill which creates accurate shapes but they are quite expensive. Whereas the Roots uses extruded rotors which are not as accurate but are much lower cost. Is there something I am missing here?

The cost is why you find the Eaton as OEM on so many mass produced cars. It is cheaper.

Although Eaton have the rights to manfacture TwinScrew blowers, I am not aware of any that they make. IFAIK, all of the Eaton OEM models are Roots blowers with the 30 or 60 degress twist. That does not changes the basic operating principle of the Roots.

IMHO, the TwinScrew design (Lysholm, Kenne-Bell/Autorotor, Opcon, Whipple, Sprintex) is superior in a number of aspects compared to a Eaton "modified" Roots in a comparison of Positive Displacement superchargers. And they make pretty much constant boost over a wide RPM range.

The upside of constant boost is you pretty much have heaps of punch on tap when you need it. The -ve is it could be harder on the internals with the sudden surge in torque.

Centrigual superchargers, such as Vortex et. al. These make more progressive boost, as has been mentioned earlier. The benefit of that as the torque increases progressivly as RPM's rise, the additional forces on the internals come on "gentler". (A slight benefit over turbos is that they can be tuned to be already spinning over pretty high at low engine RPM's, to give some low-down boost.) The -ve is that you don't get that tire-frying low down grunt.

It would be interested is seeing what sorts of developments pan out.

Cheers,
Hymee.

PS - I wonder if the Millenia's twin-screw's characteristics suit the Renesis? What I need to find out is the displacement / revolution, and the max RPM it can operate at (RPM of the blower, not the motor).

Hymee,


You took my quote completely out of context. My entire post was redarding rotor clearances and efficiency.

God gave us 14.7 psi of boost at sea level. This is simply the weight of earth's 100 mile high atmosphere. At 5000' in Denver, Colorado,
this "God's boost" would be only 12.2 psi, as the atmospheres height at 5000' is only 99 miles high vs 100 miles at sea level. So, of
course, your non supercharged engine will perform better at sea level where it has more boost (14.7 vs 12.2). Without this atmospheric
weight or "boost," the engine would not run. Why? Because an engine creates a vacuum as it rotates thereby allowing the higher
pressure atmosphere to rush in and fill the vacuum with 14.7 psi of boost. Note: This boost does not show up on a typical 0-20 psi / 0-30"
Hg gauge as 14.7 but instead as "0" on the 0-30" Hg scale. Now imagine on an ascending scale that the 30" Hg is 0 psi and the 0" Hg is
14.7 psi and you have an "absolute" pressure gauge.Add the 20 psi to the 14.7 psi and the gauge markings would be 0-34.7. Floor the
throttle at sea level and the gauge will read 14.7 psi and 12.2 psi in Denver (with "0" inlet restriction). With a supercharger and 6 psi
boost, your new absolute pressure gauge will read 20.7 (14.7+6=20.7) at seal level and 18.2 (20.7-2.5=18.2) in Denver. Here's how
you determine if your engine is utilizing all of "God's boost." If the gauge reads 4" of vacuum at wide open throttle, your engine is losing
13.6% of it's power or 2 psi of "God's boost." This is a simple equation that few really understand. 2 psi lost÷14.7=13.6% HP loss. To
eliminate the pressure losses, install larger non restrictive inlet components (filter, MAF meter, throttle body and/or inlet manifold). The
2 psi loss with a 6 psi kit (18.7 psi absolute) is 2÷18.7=10.7% HP loss. This is a big number as 10.7% of the supercharged HP is 32
whopping HP on a 300HP engine. Whether fuel injected or carbureted, ALWAYS try for a "0" reading. That's the way we've done it at
Kenne Bell since the 60's.O.K., now let's talk a little about choosing a supercharger.
There are many factors to consider when purchasing a supercharger. For one, "bigger" isn't necessarily "better." You don't buy the
biggest carburetor or injectors - or tires just because they are "bigger." So you should never buy a supercharger based solely on size or
rating. Before making a decision, one should first understand the basic terminology (size, ratings, volumetric efficiency, thermal
efficiency and adiabatic efficiency).We will attempt to make this a no B.S. straight forward overview of supercharging.
Asupercharger is merely an air pump that pumps more air into the engine than the engine, which is also an air pump, can discharge or
exhaust. The excess air from the supercharger creates a back pressure which we commonly refer to as boost. 1 psi of boost is
approximately 13RWHP. For example:Agood 300HPengine is pumping out or sucking in approx. 450 cfm at 6000 rpm (see Kenne Bell
FAQ's "I'm confused about cfm and HP"). So if the supercharger pumps 850 cfm into the 450 cfm engine, the result will be a back
pressure build up (boost). The more air the supercharger pumps in, the higher the boost and theoretically, the higher theHP.
If boost drops off with an unrestricted inlet as engine rpm increases, that is a tell tale sign the supercharger volumetric efficiency (air cfm
in vs. air cfm out) is dropping off. That's exactly what happens with the Eaton supercharged '03 Cobra. It loses 3 psi boost from boost
drop off (13-10 psi) and the HP from the lower boost decreases power by 39HP (1 psi=13HP) Then there's the higher power
consumption of the Eaton. More on that later. Volumetric efficiency indicates how efficiently the supercharger breathes and leaks. For
example: If a supercharger has a displacement of 10 liters but only 7.2 liters exits the supercharger, then it has a 72% efficiency.
7.2÷10=72%. It's as simple as that. When the VE drops off, so will the cfm, boost and engine HP. If the VE is low, the boost is low.
Remember, lower cfm supercharger output equates to less boost. Boost will not drop off with a supercharger that has a high volumetric
efficiency throughout the engine's rpm band. The Kenne Bell Twin Screw supercharger maintains the same rated boost throughout the
engine's rpm, so the Twin Screw enjoys a high VE at any engine rpm.At higher boost levels in the Lightning and Cobra, the Eaton boost
- and VE - drops sharply. Centrifugals have a relatively poor VE at the low and mid range rpm band, but are equal to the Twin Screw at
peak boost.
Basically, this indicates how efficiently the supercharger utilizes the energy (HP) that "drives" the supercharger. A high adiabatic
efficiency means the supercharger consumes less energy (HP) from the engine to drive it, thereby leaving more engine power for
acceleration - and higher dyno numbers. A low adiabatic efficiency means the engine must "waste" more of it's HP output to drive the
supercharger. This is a very important consideration because the higher the parasitic loss/power consumption of the supercharger, the
more HPyour engine must "waste" to drive it. This clearly shows up on a Dynojet when 2 superchargers are tested on the same engine
with equal boost. Two superchargers may have comparable volumetric efficiency (VE) but one may have lower power consumption
(higher adiabatic efficiency). That is the case with the Lysholm 2.3L vs the Kenne Bell/Autorotor 2.2L which uses approx. 10% less
power (HP) than the Lysholm 2.3L. The Kenne Bell/Autorotor 2.4L has a comparable VE, but the power consumption and discharge
temp are both better than the Lysholm 2.3L(See "PerformanceTests").
Temperature efficiency is the difference between the temperature entering the supercharger as compared to the boosted discharge air
temperature. Superchargers with lower air temperatures are more "temperature efficient" than those with hotter discharge
temperatures (See "Twin Screw vs Roots"). Be aware that a temperature reductionAFTER the supercharger will not make more HP -
as many experts would falsely lead you to believe. It's impossible. At Kenne Bell, we understand intercooling. We've done it for 16
years. Look at it this way. Your supercharger discharges 90 cfm of air in one revolution. Now let's trap all that air in a balloon. The
oxygen in the balloon will always weigh the same regardless of how much it is cooled. Then how can this trapped airmagically acquire
more molecules? It cannot. So always remember - cooling air after the supercharger cannot make more power and therfore,
UNDERSTANDINGBOOSTPRESSURE
SUPERCHARGERS
VOLUMETRIC EFFICIENCY
ADIABATIC EFFICIENCY(OVERALLEFFICIENCY)
TEMPERATUREEFFICIENCY
intercoolers do not increase HP. When will everyone out there get this right? The cooler air will, however, allow the engine to run
more ignition advance and/or more boost on a given octane. Obviously, cooler air the supercharger increases power at the
rate of1%for ever 10º. So lose that power robbing underhood exposed filter.
Superchargers are rated by liters (L) or cubic inches (cfm). For example;An Eaton 90 (90 cu.") is actually 1.5L. One should exercise
extreme caution in using supercharger "ratings" as the only criteria in selecting a supercharger. These ratings can be deceiving.
Just look at the differences in HPand efficiencies between the Eaton 90 (1.5L) and Kenne Bell 1500 (1.5L). See comparison tests in
our catalog and website (dyno test comparison "Positive Reinforcement," "Eaton vs. Autorotor in a Supercharger Slugfest" and
"Snake Bite Hit" (Eaton 112 vs. Kenne Bell 2.2).
Now that you understand the 3 basics of supercharging, let's assume that two superchargers have identical 1. volumetric efficiency
2. power consumption/parasitic HP loss and 3. discharge temp at 6000 engine rpm. Further assume these superchargers take
turns blowing air into an engine at 6000 rpm. Since an engine has no eyes or fingers, it cannot possibly distinguish between the 2
superchargers. The engine only sees air flow/cfm and boost. Subsequently, the superchargers will both produce the same HP.
Why?Again, the 1. power consumption 2. cfm/boost and 3. temp are identical. There is no "4th dimension" or unknown source of
power that will make one supercharger produce more power than another. Let's summarize: If 2 unrestricted inlet superchargers,
regardless of type or manufacturer, have the same VE, power consumption and discharge temp, then both will produce exactly the
same peak HP. If more power is required, then raise the boost level. Boost is what makes the power. That's what superchargers do.
They make boost. However, it is very important to understand that they don't allmake the same boost at 2000, 3000, 4000 and 5000
- so they cannot possibly produce the same HP at 2000, 3000, 4000 and 5000. For example: Centrifugal superchargers are also
very efficient, but where they produce the most cfm and boost. At lower engine speeds, the centrifugal
produces proportionately less air and, therefore, less boost (engine back pressure) and power.
The Twin Screw produces approx. the same boost at any engine rpm. Every revolution of the Twin Screw delivers the same cfm or
liters per revolution i.e. 2L per revolution at 2000-6000. That's why these superchargers are referred to as "positive displacement."
Unlike a positive displacement supercharger, the centrifugal might produce 1/2 L@1000 engine rpm, 2/3L@2000, 1L@3000, 1-
1/3L@4000, 1-2/3L@5000 and finally 2L@6000. That's because the centrifugal relies on engine speed to generate exponentially
higher cfm/L - and boost. Boost is approx. 1 psi per 1000 rpm on a 6 psi centrifugal kit whereas the boost may be 6 psi at 2000-6000
on a positive displacement type.
The centrifugal boost curve is not exactly linear as indicated above, but it's close enough for discussion. For example: Here's an
actual test. 11 psi at 6000, 7 psi@5000, 4.5@4000, 2.5@3000. What's important to remember is that the Twin Screws pump out
approx. the same displacement or cfm per revolution at any engine speed. Twin Screw efficiency (actual displacement or cfm
discharged) will depend on the overall design of the supercharger itself. Besides VE, temperature efficiency and power
consumption, you should obviously also consider a superchargers construction and it's reputation for performance, reliability and
longevity. Equally important is the manufacturers reputation for tech support and service.
For those interested in additional information and technical discussions, there are numerous SAE (Society of Automotive
Engineers) papers written on supercharging.
entering
only at higher engine speeds
SUPERCHARGERRATINGS&OUTPUT

Kenne Bell (http://www.kennebell.net/techinfo/general-info/SC_efficiency.pdf)

holy snikes that is one long arse post, so what are you trying to say anyway? heh

Originally posted by babylou
Hymee,

You took my quote completely out of context. My entire post was redarding rotor clearances and efficiency.

Sorry if you thought I was arguing with you. I quoted you because I wanted to add some more to what you were saying. I wasn't flaming you or arguing with you. I didn't dispute the facts about rotor clearances and efficiency.

My personal view is the twin-screw is much more efficient (from my research). I just made the point that the reason that the Eaton is so popular in OEM circles is purely cost based, and not because it is superior.

I'm sorry if you misunderstood my point.

Cheers,
Hymee.

I own that book already. For those that don't, thanks.

To just read something in a book is meaningless. To understand it is knowledge. Interpret it for us.

Originally posted by canaryrx8
holy snikes that is one long arse post, so what are you trying to say anyway? heh
Heh, I own a supercharged vehicle and have dynoed on both the eaton an kenne bell and the KB always made 40+rwhp more at less boost(14psi VS 13psi). I'm hoping to help out fellow gurus with my blower and nitrus experience. :)

I'm a bit confused about the "intercooling after the supercharger doesn't add power" bit. I know for a fact people have upgraded the IC on their FD and dynoed with more power with NO other changes. Perhaps it is reduced pressure drop then?

jds

Originally posted by bureau13
I'm a bit confused about the "intercooling after the supercharger doesn't add power" bit. I know for a fact people have upgraded the IC on their FD and dynoed with more power with NO other changes. Perhaps it is reduced pressure drop then?

jds

There are ways that intercooling can hurt or help make power. If the intercooler isn't getting enough air, it will heat up and store air. It is now an interheater. The other way that it can hurt power is if the piping is so long and restrictive and the intercooler core is so poorly flowing that it actually takes more boost to get the same amount of power that it had without. This can happen. Usually a good intercooler with proper ventilation will easily help make more power. If you are under boost for long periods of time you are suseptible to heat soak. This will hurt performance after a while. Generally though an intercooler helps make more power. As with anything there are always exceptions but proper intercooling will always make more power than without it. It's not difficult to do it properly so there is no excuse not to.

"Your supercharger discharges 90 cfm of air in one revolution. Now let's trap all that air in a balloon. The
oxygen in the balloon will always weigh the same regardless of how much it is cooled. Then how can this trapped airmagically acquire
more molecules? It cannot. So always remember - cooling air after the supercharger cannot make more power"

"The cooler air will, however, allow the engine to run
more ignition advance and/or more boost on a given octane"

This is after the air is compressed and no air can add to it even if it gets cooler. So since after the air is in your motor it's density cannot increase or decrease, the only reason for cooling it would be to prevent knock. This is VERY important when talking about the not so knock friendly rotory.

So I would rather be pushing a higher volume of air at lower pressure and cooler temp through my motor. That is why we all toss the "Heaton" as it's known for twin screw blowers. One of these on an RX8 would be the safest and most efficient way of making power.

Originally posted by rotarygod
If the intercooler isn't getting enough air, it will heat up and store air. It is now an interheater.

Huh? I think you didn't say what you were thinking because your statement is obviously incorrect.

Originally posted by RoTaryStYleZ
Bottom Line Best Super Charger is a Centrifical Supercharger, a Screw Type is Mainly used for Trucks and gets the back burner on this one, Roots and Centrifical are the best, Centrifical puts out more boost more on the lines to 17 18 psi, and Has to Blow off

I don't see how Roots is better than Twin-screw (same costs and integration, better adiabatic efficiency for twin screw because of internal compression) !? Centrifugal superchargers only work at high rotating speeds and thus usually at high engine operating speeds.

Drewstein,

While I understand your arguement... unfortunately one of your basic assumptions is incorrect. You are assuming that the supercharger/turbocharger flows the same amount of air at a fixed speed. This is not the case. The engine is a volumetric flow device. It moves a specific volume of air at a given speed. If I can make the air more dense... then I can increase the number of air molecules that fit inside that volume. When I burn that air with fuel I can make more power. As a result, engines make more power on cold days then they do on hot days and engines with (well designed - low pressure loss and high effectiveness) intercoolers make more power than engines without. I'm sorry you've had this wrong for 16+ years but you have. The facts are that the super/turbo charger will be operating on a different part of it's corrected speed line with and without an intercooler. Efficiency, flow and surge margin will be changed due to the intercooler. In order to verify this all you have to do is put together a simulation to see what happens. I will submit a simple EXCEL spreadsheet to characterize this behavior with and without intercooling to back up my claims. Please note: I'm not trying to flame you. I'm just pointing out a different perspective on this topic.

Regards,
Turbine_pwr

Turbine,

Nice graphs / analysis.

Can I ask one thing? I suppose you are really showing the effect of intercooling, but you lump turbo's and superchargers together. Turbo's and centrigugal blowers don't make constant boost (increases with shaft RPM), while PD blowers make constant boost over a wide operating range.

Not flaming you - like I said, nice stuff. I'd like to take it further, and compare many other factors on a screw.

Well done!

Cheers,
Hymee.

Originally posted by babylou
Huh? I think you didn't say what you were thinking because your statement is obviously incorrect.

If you install an intercooler in a hot engine bay with no ventilation running through it what so ever so it can't easily get rid of heat, not only will it pick up ambient engine bay heat but it will also not be able to dissipate heat that the turbo/supercharger is introducing it. Since it is now storing heat it becomes an interheater. An air/air intercooler only works good if it gets enough flow across it to dissipate the heat introduced into it. Most do. Think about it a little harder. The statement was fine. The interpretation was incorrect.

Originally posted by Drewstein
"Your supercharger discharges 90 cfm of air in one revolution. Now let's trap all that air in a balloon. The
oxygen in the balloon will always weigh the same regardless of how much it is cooled. Then how can this trapped airmagically acquire
more molecules? It cannot. So always remember - cooling air after the supercharger cannot make more power"



The colder balloon while weighing the same and possessing the same number of molecules as the hotter one, will be physically smaller in size. The molecules are not increased or decreased. The smaller balloon molecules are not moving as much so they are closer together. We learned all of this in junior high physical science class btw. Since the colder air is more dense, it takes up less space. The less space it takes up the more room there is for more air molecules. You are correct in the sense that cooling the air does not make more air molecules. That would be impossible. By cooling them and keeping them closer together we do have room to fit more molecules in the same space.

So always remember - cooling air after the supercharger makes more power because it leaves us more room to fill up with more air molecules. More room for air is also more room for fuel. More air and more fuel equals more boom which equals more power.

Also by cooling the temperature down we are also affecting the actual temperature of combustion. It may not seem like much but the higher the combustion temperatures and pressures, the easier the onset of detonation and the lower the total power potential. How is proper intercooling bad again?

Makes sense to me, like a peltier semiconductor.

i just like typing the word peltier

Originally posted by rotarygod
There are ways that intercooling can hurt or help make power. If the intercooler isn't getting enough air, it will heat up and store air. It is now an interheater. The other way that it can hurt power is if the piping is so long and restrictive and the intercooler core is so poorly flowing that it actually takes more boost to get the same amount of power that it had without. This can happen. Usually a good intercooler with proper ventilation will easily help make more power. If you are under boost for long periods of time you are suseptible to heat soak. This will hurt performance after a while. Generally though an intercooler helps make more power. As with anything there are always exceptions but proper intercooling will always make more power than without it. It's not difficult to do it properly so there is no excuse not to.

Hymee,

Of course, you are quite right. I was using a fairly crude approach... mostly to show the affect of intercooling. I would like to find a set of compressor maps for supercharger and turbocharger designs and incorporate them into a real thermodnamic analysis program that includes duct losses and intercooler effects (ideally effectiveness maps and pressure loss relationships). Turbo maps are easy to come by but supercharger maps are a bit harder to find. It may take a while but I'm considering going back to basics and using basic design equations for an axial compressor to evaulate it's utility in a supercharger application. On the far right of the spreasheet I posted earlier... I show that a direct drive axial compressor or for that matter centrifugal compressor supercharger would have to operate over a very wide speed range (approx 10-100% speed) in the Renesis. This is a much wider operating range then is typically used in gas turbines. As a result, it may introduce operability problems. I'm curious if anyone has looked into this subject before??? Comments anyone?

Turbine,

Your right about the speeds of centrifigual compressors currently uded in automotive apps. If you look inside them there is a pair of step-up gears, and there is a BIG difference in the size of the two.

http://www.capa.com.au/pics/powerdyne_belt.jpg
http://www.capa.com.au/pics/paxton_cutaway.jpg

I imagine the mechanical force needed to spin one up is a bit like those old hand operated air-raid sirens!

I haven't seen much about axial flow in automotive terms, but I suspect it is what is used in gas-turbines? I can't recall details, but my memory seems to recall this term in relation to WWII aero engines - such as the Rolls Royce Merlin, having a "axial flow" supercharger mounted on the front of the crank. I just guessed it was a variant of centrifugal type.

Some beautiful pictures here of a 1/5 scale Rolls Royce Merlin here, including the crank-driven supercharger (16-18PSI) (http://www.enginehistory.org/merlin_xx.htm)

I would like to get a hold of all the data/specs/curves for a variety of these devices (centigugal/screw) etc.

I like the twin-screw for the following reasons:

Constant boost
Efficient at high RPM's = wide operating range
Higher efficiencies (both mechanial and thermal)
Allows for a fre-flowing exhaust (manifold) design (compared to a turbo).

I would like to make a comparison, investigating many of the variables we talk about. Including non-intercooling and the trade off in having less advance. I'm not doubting the effectiveness of a well designed intercooler. But it introduces complexities, and it also introduces other factors - such as the reduction in boost (your analysis correctly factored in). Sure - you can add more boost to make up for it. Then you have raised the temp again, and require even more HP to drive the blower. This is a bit of a vicious circle! The fun would be working out an ideal situation/trade-off between all the things working against it.

I guess at the end of the day, it is practical experience that will count. But I'm sure that the theory equipped with the operating data will help get something close to a good starting point.

Here is another question - What is really suspect to breakage inside a 13B due to high torque? A PD blower will theoretically raise the Torque curve by a % across the board. Normally it is too high RPM that busts engines - when talking about reciprocating ones. We don't have that problem as such, but I guess there are other gotchas lurking! I would like to raise the HP without raising the RPM. Getting a fatter area under then curve, rather than just a pointier peak.

Cheers,
Hymee.

Originally posted by rotarygod
If you install an intercooler in a hot engine bay with no ventilation running through it what so ever so it can't easily get rid of heat, not only will it pick up ambient engine bay heat but it will also not be able to dissipate heat that the turbo/supercharger is introducing it. Since it is now storing heat it becomes an interheater. An air/air intercooler only works good if it gets enough flow across it to dissipate the heat introduced into it. Most do. Think about it a little harder. The statement was fine. The interpretation was incorrect.

This is not what you stated earlier. Earlier you said the intercooler would "store air". I see now that you meant "store heat".

Anyways, the above explanation of yours is only correct if the engine bay temp is higher than the outlet temp from the compressor. Under hood static temps are usually in the 140 F range. Under significant boost a compressor outlet temp will be in the 200 F range. Therefore your theory is good on paper but not in practice.

ok... so whatever happened to this smokinjoe supercharger? Did these forum arguments give them a headache?

Originally posted by babylou
This is not what you stated earlier. Earlier you said the intercooler would "store air". I see now that you meant "store heat".

Anyways, the above explanation of yours is only correct if the engine bay temp is higher than the outlet temp from the compressor. Under hood static temps are usually in the 140 F range. Under significant boost a compressor outlet temp will be in the 200 F range. Therefore your theory is good on paper but not in practice.

Yup I reread it. I said store air instead of store heat. That's what I meant. Typos happen.

You still aren't understanding it though. I'm about to have to draw a picture. The engine bay temp is irrelevant. It doesn't matter where the intercooler is mounted. This applies to intercoolers that have zero or poor airflow across them. If the intercooler can not get rid of heat it keeps it. Since the air coming out of the turbo when under boost is hot, we'll say 200 F from your post, the intercooler has the potential to also reach 200 F. This is only if it does not have ventilation and can not get rid of this heat. The intercooler has to absorb heat so it can pass it on to the surrounding air. If it can't pass it on, it keeps it. Once this happens, it takes a while to cool back down. Most intercooler systems do have adequate ventilation and airflow across them so this isn't an issue. It can happen though in theory and most certainly in practice and it does happen. If there is no airflow across the core, there is very little heat rejection. If there is poor airflow across the core, there is little heat rejection and more stored heat. More stored heat is less dense air. Less dense air is less air. Less air is less power. This is how an intercooler has the potential to hurt power. It is only if the system was designed badly. Luckily most of them help.

Originally posted by rotarygod
So always remember - cooling air after the supercharger makes more power because it leaves us more room to fill up with more air molecules. More room for air is also more room for fuel. More air and more fuel equals more boom which equals more power.

Proper intercooling is not bad, it's aftercooling that isn't really worth it as far as "adding power. Proper cooling just helps the motor run closer to "perfect" conditions. You're saying there is room for more air, but how does that air get there? With a swin screw blower fixed to your motor, the only air entering the motor must pass through it. This means that the volume of air is fixed once it passes through your supercharger wether it's cool or not. If it is cooled then there will be more room for more air molecules, but no molecules are going to show up or magically appear. However if the air was cooler before entering the supercharger where it can get more dense because it's not sealed off from outside air, then you would see an increase in volume at a given psi. So since the baloon does get smaller, the only thing you can ad more of is fuel. I don't know if that's good or bad, but it's the only substance that can be introduced once the air passes through the blower.

Now by using a twin screw over a roots, your air temps drop causing volume to increase. That is just one advantage over the roots. Also, since the 8 can use low end grunt and top end pull equally, it makes more sense to use these over centrafugal blowers. Making constant boost at 1000rpm through 9000rpm would fatten up that curve nicely.

Aftercooling and Intercooling are really the same thing in normal usage of the words. They both cool the charge after it has been compressed. It is the compressor that heats it up.

I'm a twin screw fan.

Cheers,
Hymee.

Originally posted by Hymee
...

...I just made the point that the reason that the Eaton is so popular in OEM circles is purely cost based, and not because it is superior.

...

Cheers,
Hymee.

Cost AND mass-production capacities

IKN

This balloon analogy is bugging me, and here's why (I may be all wrong, so if I am let me know). The supercharger is constantly taking a handful of air molecules, compressing them, and shoving them into the engine. The engine itself is constantly taking mouthfuls of air molecules that are sitting there (under pressure). However, these two events aren't really linked in any sort of 1:1 ratio, right? The "balloon" full of compressed air that shoots through the supercharger at a given moment is not necessarily the exact amount needed in the next intake cycle. The air waiting for the engine to take it is at a pretty constant pressure, assuming you're at full boost, so its not like the SC puts the air in the balloon, the engine takes exactly that balloon full of air, and then the SC gets another one ready. Its constantly shoving them towards the engine faster than the engine can take it (hence the greater-than-atmospheric pressure) and so the more you cool it down, the larger the percentage of the available pressurized air the engine can take in a given intake cycle.

Right?

jds

Originally posted by Drewstein
Proper intercooling is not bad, it's aftercooling that isn't really worth it as far as "adding power. Proper cooling just helps the motor run closer to "perfect" conditions. You're saying there is room for more air, but how does that air get there? With a swin screw blower fixed to your motor, the only air entering the motor must pass through it. This means that the volume of air is fixed once it passes through your supercharger wether it's cool or not. If it is cooled then there will be more room for more air molecules, but no molecules are going to show up or magically appear. However if the air was cooler before entering the supercharger where it can get more dense because it's not sealed off from outside air, then you would see an increase in volume at a given psi. So since the baloon does get smaller, the only thing you can ad more of is fuel. I don't know if that's good or bad, but it's the only substance that can be introduced once the air passes through the blower.

Now by using a twin screw over a roots, your air temps drop causing volume to increase. That is just one advantage over the roots. Also, since the 8 can use low end grunt and top end pull equally, it makes more sense to use these over centrafugal blowers. Making constant boost at 1000rpm through 9000rpm would fatten up that curve nicely.

Originally posted by rotarygod
Yup You still aren't understanding it though. I'm about to have to draw a picture. The engine bay temp is irrelevant. It doesn't matter where the intercooler is mounted. This applies to intercoolers that have zero or poor airflow across them. If the intercooler can not get rid of heat it keeps it. Since the air coming out of the turbo when under boost is hot, we'll say 200 F from your post, the intercooler has the potential to also reach 200 F. This is only if it does not have ventilation and can not get rid of this heat. The intercooler has to absorb heat so it can pass it on to the surrounding air. If it can't pass it on, it keeps it. Once this happens, it takes a while to cool back down. Most intercooler systems do have adequate ventilation and airflow across them so this isn't an issue. It can happen though in theory and most certainly in practice and it does happen. If there is no airflow across the core, there is very little heat rejection. If there is poor airflow across the core, there is little heat rejection and more stored heat. More stored heat is less dense air. Less dense air is less air. Less air is less power. This is how an intercooler has the potential to hurt power. It is only if the system was designed badly. Luckily most of them help.

To make the intercooler core peak temperature greater than the peak compressor outlet temperature one would viollate the laws of thermodynamics. The only way your above scenario does not violate the laws of thermodynamics is:

1. Run the system at high boost for a lengthy period of time to heat the intercooler mass to the same temp as the compressor outlet temp. Lets' say 200 F. For simplicity we will ignore the cooling due to convection currents and radiation.
2. Let off the throttle and run at a lower compressor boost and therefore a lower compressor outlet temperature of say 150 F. Now the 200 F intercooler is heating the 150 F intake charge.

The only problem with the above theory is you are only reducing the part throttle intake charge density. At full throttle and full boost the compressor outlet temp is already 200F and cannot be heated more. Therefore, power output is not affected.

If you know a way to make the intercooler have a higher temp than the max outlet temp of the compressor please let me know. I will then congratulate you because you have just invented a perpetual motion machine.

You may not realize it but you actually just completely agreed with me!

If people still don't understand then I give up. It's not my fault if others can't learn. It is so simple that it baffles me why people don't get it. Think harder. Actually, don't think so hard. Maybe that's the problem.

I think what RotaryGod is saying is that the intercooler needs to disappate heat.
If there is not enough ventilation, it disappates the heat very slowly. If it is not disappating the heat, it is not helping anymore (once it hits peak temp), and is actually hurting at partial throttle settings.

Reeko,

Nice summary!

Cheers,
Hymee.

dang Guys ,
Seems simple to me. More fuel in, the bigger the explosion, the more power you have. I know, I know the timing and a/f ratio and all that stuff has to be right BUT, the more fuel in (properly) the more power you have. end of story. Now will someone please build a supercharger system for this car!? I would be extremely happy with only 275-300 whp!
Ya want to talk about heat? Hell we already have a heat problem. In georgia in the summer the air temp inside the airbox is over a hundred degrees.!
olddragger

Originally posted by rotarygod
You may not realize it but you actually just completely agreed with me!

If people still don't understand then I give up. It's not my fault if others can't learn. It is so simple that it baffles me why people don't get it. Think harder. Actually, don't think so hard. Maybe that's the problem.

The heck if I agreed with you. Also, your responses of "you need to think more" is simply saying I am an idiot and is not helping to prove your point. Let's stick to science.

Earlier you stated: "If there is no airflow across the core, there is very little heat rejection. If there is poor airflow across the core, there is little heat rejection and more stored heat. More stored heat is less dense air. Less dense air is less air. Less air is less power. This is how an intercooler has the potential to hurt power."

The last sentence clearly stated an intercooler has the potential to hurt power due to thermal reasons. As I explained earlier this is thermodynamically impossible except during part throttle operation after a long period of full throttle operation. In case you are unfamiliar with the scientific methods of testing an engine I will tell you that engine power is tested at full throttle. Also, if for some reason your engine is loping along at part throttle and you are wanting more power just push the throttle pedal a bit closer to the floor. By the time the pedal touches the metal the power will be the same. Unless of course Isaac Newton was wrong with all those laws he discovered.

Originally posted by olddragger
Now will someone please build a supercharger system for this car!?

I'm keen. If I new I had critical mass of customers I'd take deposits right away!

Cheers,
Hymee.

Originally posted by babylou
The heck if I agreed with you. Also, your responses of "you need to think more" is simply saying I am an idiot and is not helping to prove your point. Let's stick to science.

Earlier you stated: "If there is no airflow across the core, there is very little heat rejection. If there is poor airflow across the core, there is little heat rejection and more stored heat. More stored heat is less dense air. Less dense air is less air. Less air is less power. This is how an intercooler has the potential to hurt power."

The last sentence clearly stated an intercooler has the potential to hurt power due to thermal reasons. As I explained earlier this is thermodynamically impossible except during part throttle operation after a long period of full throttle operation. In case you are unfamiliar with the scientific methods of testing an engine I will tell you that engine power is tested at full throttle. Also, if for some reason your engine is loping along at part throttle and you are wanting more power just push the throttle pedal a bit closer to the floor. By the time the pedal touches the metal the power will be the same. Unless of course Isaac Newton was wrong with all those laws he discovered.

I never said or implied that you are an idiot. That was all you buddy! What I did say is that you are either overthinking the situation or are overlooking something. Nowhere did I say anything about your intelligence level. Smart people miss things too! Forget science. Let's stick to common sense! Science won't help me cross a street during traffic and it won't help here either.

It's obvious I'm going to have to pull out the good old automotive based book from Corky Bell to quote rather then a science book to quote from. This first example is how an intercooler "could" be setup to not be worth it's presence. Lets say you place an intercooler in the engine bay behind the radiator. Not a good idea. The only ventilation it gets is from the hot radiator air. Let's say that ambient outside air temperature is 90 degrees and the air after it has passed through the intercooler is at 140 degrees. Just a figure so don't get into actual numbers. This air will do a lousy job of trying to cool anything. At low or no boost levels the supercharger or turbocharger may not have an outlet temperature that is as high as the ambient intercooler heat. Therefore the air gains heat as it passes through the core. In this scenario it becomes an "interheater" as it is adding heat to the system. When boost rises to the point that the temperature of the charge exceeds the underhood temperature, the intercooler will begin doing some work but will forever suffer from a severe efficiency loss. If the small reduction that it is still giving in temperature is not enough of a gain to overcome the pressure loss through the core and piping, then there was no point in having it there in the first place. Most importantly, the engine bay is no place for an intercooler. That is only ONE possible scenario.

The same thing can occur in a system that has very poor ventilation but is not in the engine bay. This could include any nonfront mount type of system that has inadequate ventilation. The amount of heat that the intercooler can pick up from the turbo can not be dissipated very efficiently with no air flow. This will store it. When the engine is under little to no boost where air temperatures are below that of the stored heat in the core, it again becomes an "interheater". When the intercooler cools down enough that it is at ambient temperature to the air flowing through it, it is no longer an interheater.

Here's a real world scenario. My best friend's '93 RX-7 is about to get a new engine. (It's a 3rd gen, of course it is!) The air duct to the intercooler is removed. The stock intercooler sits in the engine bay. There is little to no ventilation across it. At least not cool air. The car is fastest after it is first started. The intercooler hasn't had time to heat up yet. After a few minutes the car starts to get slower. The intercooler isn't getting rid of the heat. It becomes sluggish on the street. Under full boost, it still does something but it isn't terribly effective.

When an intercooler system is designed and installed properly, it has little pressure loss internally and is properly ducted to receive good airflow. This high amount of airflow easily serves to help heat escape from the core when under boost. The more heat that can get out of the cooler, the more heat can enter it and the more heat that can be taken away from the air inside of it. Any cooling benefit of an intercooler is an advantage for power over using no intercooler as long as there is not a huge pressure drop that is offset by the denser air gain. This is how every successful intercooler system works and how most everyone does it. When done properly, there are no drawbacks as far as power production is concerned to using an intercooler and only gains to be had. Any issues with drivability are minimal. Again this assumes a good design.

Another thing which happens is heat soak. This applies whether turbocharged, supercharged, intercooled or not. When the engine has been under boost really hard, the hot air through the system eventually starts to build up. This is true as long as the intercooler can not dissipate the added heat fast enough. At this point everything in the intake system starts to get hot and hold heat. The pipes, intercooler, intake manifold, etc. all start getting hotter. This heat in the system makes the car a little slower. The only solution once that happens is to not drive so hard until the car cools down or to redesign the intercooling system. This usually applies to track driven street cars. It can also happen to any car when sitting still in traffic. Hot air from the radiator fan is blowing into the engine bay but there is little airflow through the intake runners to help dissipate the heat. Let your car idle for a while sometime with the hood closed and then open it and touch the manifold. It's hot. Then go for a drive and immediately touch the manifold after you stop (of course after you stop!). It is much cooler. This was heat soak and for a short time even the manifold worked as an "interheater". It happens everyday to every car.

You are interpreting the "interheater" statement to imply that it is always heating up the air like an oven when it is a part time phenomenon. You are so concerned with trying to prove me wrong that you are entirely overlooking the fact that you already have it figured out. I didn't say you were an idiot. You are overlooking the obvious though. Put down the science books for a while an use common sense. At the very least pick up an automotive based book that deals directly with the topic rather the the physics behind it. There was another thread on here where the members were trying to argue how coefficient of drag and tire width were the reason why another members car slows down more when going down hill than another car. Thie arguments were ludicrous and pointeless. The real issue is that something mechanical in the vehicle is slowing it down such as brakes dragging, etc. Those guys were obviously intelligent in the ways of science, but overlooking the obvious in the real world. I said it over there but I'll say it again here.

"That's why we have mechanics. It's because scientists don't know anything about cars!"

Do you understand now? And stop taking it so damn personally!

rotarygod,

You keep changing your what ifs. I see in scenario number one now the cooling air is hotter than the charge air. This was never discussed before.

Also, all you talk about is part throttle effects and how the power is being reduced at part throttle. Like I said before why don't you push the pedal farther? Once at full throttle you will be at the same exact power. Why do you refuse to discuss this?

In your sixth paragraph you again revisit the topic of building up air. Are we talking about a car or a hot air balloon here?

Your real world scenario showing that the car loses power after the intercooler heats up is worthless. Your example does nothing to show an intercooler is losing power versus no intercooler. It simply shows how a hot intercooler loses power versus a cold intercooler. Study up on the scientific method.

I'm glad you possess common sense mechanics and Corky's book(s). Since it appears I have no common sense I am forced to stick with my science based education of thermodynamics and heat transfer that I studied, the same as Corky Bell, at Texas A&M University.

C'mon guys,

Don't ruin a good thread. Just agree to disagree :)

Cheers,
Hymee.

I'll throw in the towel. It's obvious you can't teach some people.

I have not once contradicted myself or changed my story especially clear when I make it clear that I am describing one of many possible scenarios. You just constantly fail to comprehend. It baffles me how such a simple obvious scenario cannot be understood. Hymee summed it all up in 2 lines. It can't be any more obvious. I'm actually dumbfounded! I'm not sure if knowing Corky neccessarily gives credibility at this point.

FWIW: Anyone can pass a test on paper. Eductation does not guarantee intelligence.

To make you happy, you win! I'm done. Be proud.

That the cooling air being hotter than the charge air is what I understood from earlier posts.

I think for part throttle he is just listing another scenario where it can happen. If it is happening in street driving you can't always be at full throttle though.

I thought he said car and FI engine in the 6th paragraph.

I am pretty sure this is going down to common sense because I am positive that you have a much better thermodynamics educaton than I do.

Originally posted by Rotarian_SC
I think for part throttle he is just listing another scenario where it can happen. If it is happening in street driving you can't always be at full throttle though.


No, part throttle is not "another scenario" but the only scenario where approach applies. Also, this scenario is only correct after a long blast at high boost. At full boost there is no loss. Period.

Who cares about part throttle? At full throttle an intercooler that is 100% heat soaked will make the exact same power as a non-intercooled system. Even after 1000 blasts down a quarter mile.

I just don't get how anyone thinks the intercooler can get hotter than the charge air at full boost. It cannot. And full boost is when we care about power. Not at 50% throttle/50% boost.

Let's try this common sense thing I've been told I lack: Put a TV dinner in the oven at 400 F. What is the max temp the TV dinner can reach? 400 F.

Now engine compartment air is ~140 F. I've tested this on maybe 10 different vehicles.

Knowing that charge air at full boost will be ~200 F please tell me what's the temp of the air entering the engine on a non-intercooled system. Yup 200 F. Okay?

Now we add an intercooler to the same engine. We run the engine at full boost for 1 hour. Remember the charge air is ~200 F at full boost. The intercooler system was designed by a scientist that lacks common sense, like me and unlike a mechanic, therefore is placed in stagnant underhood air at 140 F. What is the temp of the intercooler? Remember that the air flowing in the intercooler is 200 F and the stagnant air around the exterior of the intercooler is 140 F. The intercooler can reach a maxiumum of 200 F. Now what is the temp of 200 F air passing through an intercooler at 200 F? 200 F

All of the above ignores any losses due to flow related effects (profile and skin drag effects). These losses have never been part of this heat soak topic.

Which is exactly what Rotarygod is saying. http://www.hymee.com/smilies/sm_doh.gif

Cheers,
Hymee.

Originally posted by Hymee
Which is exactly what Rotarygod is saying. http://www.hymee.com/smilies/sm_doh.gif

Cheers,
Hymee.

It seemed to me that rotarygod was saying a poorly designed intercooler will become so hot it will actually heat the charge air and therefore actually reduce power potential versus a non-intercooled engine. I believe he coined the term "interheater".

The way I read it, you are both saying the same thing. If your heat-exhange element is hotter than the incoming charge, it will heat the charge (afterheater/interheater) and if it is cooler than the charge it will cool it (aftercooler/intercooler).

Cheers,
Hymee.

Originally posted by Hymee
The way I read it, you are both saying the same thing. If your heat-exhange element is hotter than the incoming charge, it will heat the charge (afterheater/interheater) and if it is cooler than the charge it will cool it (aftercooler/intercooler).

Cheers,
Hymee.

I keep saying this: You can only heat the charge at part throttle and this has no effect on performance. At full throttle it is impossible to heat the charge air. Full throttle is what affects power potential.

Man I wish I knew how to post one of those smileys bashing my head against a wall. Obviously a few other people wish I would bash my head.:D

I do agree that we have beat this topic to death.

Peace,
Babylou

Originally posted by babylou
At full throttle it is impossible to heat the charge air.

I respectfully disagree. http://www.hymee.com/smilies/sm_hiding.gif

The air molecules don't say "Hey was that butterfly fully open - if it was, I'm not gunna swap some of heat energy with this hot bit of radiator fin I just bumped into."

If there is a temperature difference between the air and the heat-exchanger, one will give up it's heat and cool down a bit, and the other will warm up a bit.

Cheers,
Hymee.

Originally posted by Hymee
I respectfully disagree. http://www.hymee.com/smilies/sm_hiding.gif

The air molecules don't say "Hey was that butterfly fully open - if it was, I'm not gunna swap some of heat energy with this hot bit of radiator fin I just bumped into."

If there is a temperature difference between the air and the heat-exchanger, one will give up it's heat and cool down a bit, and the other will warm up a bit.

Cheers,
Hymee.

Okay last try here. I can't handle fighting this two front war.

1. In your first paragraph you speak of the butterfly being fully open which is the same as full throttle. Agreed?

2. Since you are talking about full throttle here the charge air will be at the maximum exit temp of the compressor. Agreed?

3. The maximum exit temp for automotive compressors is ~200 F. Agreed?

4. The air temp underhood is ~140 F. Agreed?

5. The intercooler is surrounded in underhood air on the exterior and compressor outlet air on the interior. Agreed?

6. An object that is heated by its' surroundings cannot exceed the temperature of the surroundings just like my TV dinner example. Agreed?

7. The highest temp, ever, of the intercoolers surroundings is the 200 F of the compressor outlet air. Agreed?

8. Since the maximum temp of the surroundings can be 200 F the intercooler temp cannot exceed 200 F. Agreed?

9. Let's assume the intercooler is very inefficient and actually reaches the theoretical maximum temp of 200 F. Agreed?

10. Now go back to my statement #3 and connect to statement #8. The 200 F compressor air is passing through a 200 F intercooler. Agreed?

11. Same temp = no heat transfer.

Please tell me, by number, which of my statements you disagree with.

Cool it!!

All I was saying was that in the case of the intercooler temp being higher than the air, the air will heat up, regardless of throttle position.

You seem to say that case can't happen. I'm not going to argue that point. Maybe it can, maybe it cannot. Maybe it is just highly unlikely.

Cheers,
Hymee.

Originally posted by babylou
2. Since you are talking about full throttle here the charge air will be at the maximum exit temp of the compressor. Agreed?

Disagree. There is the possibility that the compressor is producing little to no boost meaning little heat. You're assuming that boost is instant as is not the case in any application. So if you mash the gas there could be a nice rush of outside air (sealed element) but the compressor hasn't spun up yet, the warmer intercooler would heat your initial air charge in fact hurting low end power. Once the air charge and intercooler both reach the same temp, then heat transfer would stop in one direction and then begin in the other direction as the air charge keeps increasing in heat.

Well put!

Summary....

In a poorly designed Intercooler (poor airflow, easily heatsoaked) the following occurs.
1)Once Heatsoaked, it hurts performance at partial throttle. Agree/Disagree?
2)Once Heatsoaked, it no longer helps (actual HP Gains) at full thottle , a good design could by not being heatsoaked as easily, therfore still providing some cooling. Agree/Disagree ?
3)If it no longer is providding cooling, then it to some level is causing some backpressure in the intake that could cause a performance penalty. Agree/Disagree?

I think everyone is saying the same thing. A poorly designed heat exchanger while providing some benefit until heatsoaked, becomes zero benefit once heatsoaked and can actually reduce power (slightly) if it inhibits airflow.

The goal then should be to optimise the heat exchanger so that it cools quickly.

Also.
Even if not completely heatsoaked, an intercooler that is running cooler will add more power than one running at a higher temp . The cooling of the aircharge is proportional to the delta between the air and the cooler. A colder running intercooler will obviously provide more charge cooling even at partial throttle positions.

Originally posted by Drewstein
Disagree. There is the possibility that the compressor is producing little to no boost meaning little heat. You're assuming that boost is instant as is not the case in any application. So if you mash the gas there could be a nice rush of outside air (sealed element) but the compressor hasn't spun up yet, the warmer intercooler would heat your initial air charge in fact hurting low end power. Once the air charge and intercooler both reach the same temp, then heat transfer would stop in one direction and then begin in the other direction as the air charge keeps increasing in heat.

Congratulations! You are correct. I was neglecting boost response of the compressor. However, I keep pointing out that this entire discussion has been simplified from the start so we have eliminated drag effects of the plumbing and transient responses (boost rise, thermal lag).

If we want to nitpick I can find other phenomena in the other direction too. The effects of thermal radiation and convection have been ignored. Or that there is delay in heat transfer from one object to another. Or the effect that a cooler intake charge leads to a cooler exhaust charge which will be less efficient at driving a turbocharger which will lead to less power. Of course these effects are small so for simplicity it is best to look at the problem in a macro sense.

Hey, I also congratulate you for scientifically responding to a specific point I have made instead of just saying "you need to quit reading books or whatever."

Originally posted by babylou
I am forced to stick with my science based education of thermodynamics and heat transfer that I studied, with Corky Bell, at Texas A&M University.

I hate to dig up a dead horse but I want to clarify a mistake I made here.

After re-reading this entire thread I see that my statement above insinuates I took the above classes with Corky Bell. This is not true. I meant that I took the same classes at the same university while we were getting the same Mechanical Engineering degrees. I'm actually a bit younger than he is. I apologize for misleading anyone.

I will now go an edit the original text.

Peace,
Babylou

Originally posted by Reeko
Summary....

In a poorly designed Intercooler (poor airflow, easily heatsoaked) the following occurs.
1)Once Heatsoaked, it hurts performance at partial throttle. Agree/Disagree?
2)Once Heatsoaked, it no longer helps (actual HP Gains) at full thottle , a good design could by not being heatsoaked as easily, therfore still providing some cooling. Agree/Disagree ?
3)If it no longer is providding cooling, then it to some level is causing some backpressure in the intake that could cause a performance penalty. Agree/Disagree?

I think everyone is saying the same thing. A poorly designed heat exchanger while providing some benefit until heatsoaked, becomes zero benefit once heatsoaked and can actually reduce power (slightly) if it inhibits airflow.

The goal then should be to optimise the heat exchanger so that it cools quickly.

Also.
Even if not completely heatsoaked, an intercooler that is running cooler will add more power than one running at a higher temp . The cooling of the aircharge is proportional to the delta between the air and the cooler. A colder running intercooler will obviously provide more charge cooling even at partial throttle positions.

Thank you!!! This is what I've said the whole time (and EVERYONE except one person agreed with me!) and was being told I was wrong about. There are CERTAIN times things can occur. Once again someone who isn't ignoring "scientific point" in one area to prove otherwise in another area. Way to go! We're probably still wrong though! Oh well. Unlike many others out there, I actually own a turbocharged car so I can go outside and prove everything I have been saying easily.

Remember education doesn't necessarily imply intelligence. Shhh... Don't tell my engineering professors I said that. Yes, I went to school for mechanical engineering too! So what. That doesn't mean anything whatsoever.

I'm enjoying reading others responses so from now on I'll just read and laugh and maybe comment about the way things are going. This is fun! Comedy Central online.

Can I get in on this???
I know I should keep out of it, but!!!
You are all very brite people, no one can deny you that.
Everyone is right but you just can't comunicate. I should talk, I'm the worst.
You guys are saying the same thing. I THINK. You all agree that the intercooler can work but it has to be in the right place at the right time.
It has problems, everything does. It's big problem is that there is so much hype out there. If you can run without one do so. If you are going to melt down then figue out how to do it right. My objection to them is running them for no reason.
On a street engine an air to air system does not get the air going fast enough to work like it does on a race car.

Try a liquid to air cooler and it may prove more practical. Of course it too has problems like it takes more time to recharge. Or to get the coolent radiator back down. It's all a matter of heat storage. Oh shit! I just started another long thinking thread.

Wait guys, I too have been to school and make my living with fluid dynamics. Like I said better not to open my mouth. I only wanted to comment so as to sooth thing down.

This reminds me of friday nights at school with beer and pizza flying around. All the smart ass know it all engineerg students yelling at each other. Trouble here is no beer.
Thing is that now I know why we did that. Because it was the art students who were out with the girls. We were stupid, girls didn't take engineering courses.


I've said it before all you get is what the compressor puts out. BUT, every drop of heat you put in goes all the way throgh. If it is cooler it will not reach the thermal limit of the internal parts. It will be more resistant to detonation. You may tune more out of it. BUT ignition advance is not an end to itself. you don't want it unless you have to have it. The more you advance it the more pressure the engine is pushing against on the compression stroke.

Will someone please take this keyboard away from me.
Forget I said anything. Because to explain myself to the degree that is required in this forum is impossable. You guys are just to demanding. I'm going with Rotorygod, I'll just read.

Originally posted by rotarygod
Thank you!!! This is what I've said the whole time (and EVERYONE except one person agreed with me!) and was being told I was wrong about.

Bullshit! You never talked of pressure losses. Never, ever, ever. I was the one that mentioned profile and skin drag effects which lead to pressure losses and that was a loss we were neglecting. Much like we were neglecting gains like thermal radiation.

QUOTE]Originally posted by rotarygod
Remember education doesn't necessarily imply intelligence. Shhh... Don't tell my engineering professors I said that. Yes, I went to school for mechanical engineering too! So what. That doesn't mean anything whatsoever.[/QUOTE]

I suppose by once again saying I'm dumb makes you feel that your point is more valid. Good for you. I can do the same: It is obvious you have a rudimentary knowledge of heat transfer and thermodynamics. I noticed you "went to school for mechanical engineering too". Nothing about graduating. I'm thinking that first calculus class and first statics class washed you out.

FFS - the argument is over. We all basically agreed. We don't need to get personal.

Lets get the topic back on track to blowers for the Renisis!

Cheers,
Hymee.

hymee the peacemaker. Always to the rescue :D

Damn, I have to break my vow of silence so soon. I just opened Turbines spreadsheets. John, we have talked in the past and I love your plots and speadsheets, nice work. Now I'm an engineer and love math as much as the other guy. With all do respect, I must side with RotoryGod on one thing.
There comes a time when we must leave the math in the office and go out into the shop.
You said it yourself, ther are two pumps working here.

You are pumping from one into another so the resistance changes because even if the pumps are both positive displacment they cannot match all along the rev range.

Next if you are talking dynamic compressor things get more complex as you also noted. So far we agree. The problem comes when you state that there will be more air going into the engine. If you are using a positive displacment pump then no more air can come out. That is a given.

If you are talking a turbo or centrifugal compressor you can get more. that is because it will give up more flow for less resistance. The problem is that you can't plot it that easy. I think you said that also. But this thread is about roots blowers, right?

You mentioned that you were ploting an axial compressor, if that is so then I know something about that. Since I'm the only one who has worked on this problem and even I don't know enough about it. One thing is for sure, the axial is 100% adiabatic and all internal compression. It doesn't like a lot of external compression.

In the case of the axial I think it would have to be resized if you were to get the most out of it. Someday I want to build a Bonniville engine with one of my blowers at about 2.5 Pr. and intercool it with ice water. That can take a bunch of BTU'S off the charge. In that set up you would have control over all the delta's.


Turbine, you and I are going to talk about this and maybe you can help me understand a few things. I have to say that some of it baffles even my old professor of turbo machinery. And He is a smart guy, ex NASA and the like. Overachiver.

Hope I mixed up the thread some more. I am not the final judge, only your dyno knows for sure

Just one more thing and this goes back in the thread a ways. The reworking of the ports on the Eaton hurt efficency. If it comes in the top and out the bottom that is better then working it around the place. Also they did not invent the helix rotor, GM has been using that design since WWll or before. The dragster blowers started out with the 6-71 back in the early '50's. They still use that rotor only streched to 19". In fact untill recently they used actual GM rotors spliced to get the 19".



Good night,
Richard

Hey Richard,

Thanks for the input. I'd like to include twin-screws in this discussion as well, if people agree. They are different than roots, but many people assume they are the same.

Cheers,
Hymee.

Hymee,

Yes, I think we can all agree on the fact that the screw is a positive displacment blower. Therefore it should be taken in the same light. However the twin-screw is more efficiant.

Richard

Originally posted by Richard Paul
Hymee,

Yes, I think we can all agree on the fact that the screw is a positive displacment blower. Therefore it should be taken in the same light. However the twin-screw is more efficiant.

Richard
Completly agree. The twin-screw positive displacement blower is what needs to be on the RX-8 IMO. After all this discoussion about temps and what not I'll point out that the twin-screw puts out lower air charge temps and more volume per psi of boost than the roots style blower. It also has a more instant boost response than centrifugal style blowers which will fatten up the curve on the 8 nicely. With no other change, I went from 380rwhp to 450rwhp in my lightning just by swapping blowers from roots to twin screw. They were both at 15psi as well. That's a 70hp gain in just blower to blower comparisons and the gains get exponentially larger as boost increases.

Mmmmm.... Sounds nice :)

I think the main mechanical concern with the rotary is lunching the apex seals due to detonation. Something to be concerned about with high temps, and possible the injectors not being able to deliver enough fuel need for the mass of air - i.e. too lean.

Cheers,
Hymee.

Ok guys great topic on which SC is best and I agree that twin Screw would work out to be the best for the RX-8. Now how do we go about and who do we put presure on to come out with this SC.. I would hate to wait a year but I could if if means having the best SC for my RX-8...

Wait, wait, wait. I didn't say the screw was the best blower, I just said it was better then the roots. It of course is only my opinion but I'm betting a lot on the axial flow being the best. That means I am putting my money where my big mouth is.

In fact I'm so sure of it that you'll notice on my thread I have built the Rx8 blower already. That in addition to that gamble we are so sure of it that we actually built 7 of them and bought the matirial for 25 more.

Truth is that they are machined, only 2 are assembled for bench tests next week. That's comitment, that's progress. We've only been on this for about 30 days.

Richard

Richard,

Is an "Axial Flow" the same as a centrifugal compressor in this contect??

Cheers,
Hymee.

Originally posted by Hymee
Richard,

Is an "Axial Flow" the same as a centrifugal compressor in this contect??

Cheers,
Hymee.

No. Axial flow means the charge air moves along the axis of rotation of the compressor. Like a modern jet engine or a series of fans placed one after another. Centrifugal means the charge air enters in the center of the compressor and is flung out radially. Picture kids on one of those spinning discs on the playground. The faster the disc spins the stronger the force that is trying to fling the kids off.

That is what I thought, but I have not seen much (any??) of this in terms of automotive apps.

Cheers,
Hymee.

Originally posted by Richard Paul
That means I am putting my money where my big mouth is.

I posted my feelings about this on the other thread.

On topic: Companies can produce the supercarger easily, but the necessary mounting hardware will need developement. I believe there are guys trying roots applications so all you would need is their hardware and a twin screw to slap on in the roots blowers place.

Originally posted by Drewstein
I posted my feelings about this on the other thread.

On topic: Companies can produce the supercarger easily, but the necessary mounting hardware will need developement. I believe there are guys trying roots applications so all you would need is their hardware and a twin screw to slap on in the roots blowers place.

You sir know nothing about supercharger integration. I'm ready to cede my username to you if you wish...

Talked to smokin joe today.Im a little hazy on what he told me though.In one sentence he told me the SC was 90% done.Then about 3 mins into the conversation he told me he may scrap the entire thing.It seems they dont believe this engine can take any kind of boost for a extensive amout of time while keeping some kind of reliability.Not the news i wanted to hear since it seems others are droping projects as well.While i believe the greddy kit is done for j-spec we may never see it here.

Compression ratio must be reduced, and that requires some rotor machining on a rotary (i.l.o. a thicker head gasket on a piston engine).

That is probly gunna be the case for some serious boost. I wonder what the reliable limit would be for people who are chasing a "bolt-on" install?

The advice given to me is that the apex seals are the most at-risk components internally. The rotors and eccentrics can take heaps of power, but detonation is the killer.

Cheers,
Hymee.

Even for medium levels of boost a reduction in compression ratio would be a must to recover some durability.

Although I have no practical experience of rotaries, I do also believe that the problem is located on the apex seals, both due to detonation and peak combustion pressure.

Without any change in internales, I'd would not consider anything more than 15 to 20% increase in air flow at medium to high engine speeds. And maybe up to 25 -30% at lower revs.
And on MY PRIVATE OWNED CAR, I'd go for a controlled boost that rises up to +0.3 bar max at low revs and goes rapidly down to +0.15 bar and die at +0.1 bar at peak power engine speed.

That was the basis for some calculation I made a couple of years ago when I was thinking about supercharging my 2.6l V6 Audi. The good thing is that most of the calculations are valid for the 1.3l rotary!

Originally posted by IKnowNot'ing
Even for medium levels of boost a reduction in compression ratio would be a must to recover some durability.

Although I have no practical experience of rotaries, I do also believe that the problem is located on the apex seals, both due to detonation and peak combustion pressure.

Without any change in internales, I'd would not consider anything more than 15 to 20% increase in air flow at medium to high engine speeds. And maybe up to 25 -30% at lower revs.
And on MY PRIVATE OWNED CAR, I'd go for a controlled boost that rises up to +0.3 bar max at low revs and goes rapidly down to +0.15 bar and die at +0.1 bar at peak power engine speed.

That was the basis for some calculation I made a couple of years ago when I was thinking about supercharging my 2.6l V6 Audi. The good thing is that most of the calculations are valid for the 1.3l rotary!

I dunno about your 2.6l calculations being that valid for a rotary. Rotarygod has gone over it before, but at the moment I am trying to hash through an explanation of rotary engines and the Renesis in a magazine given by Seiji Tashima... head rotary engine engineer on not only the Renesis, but also 13B-REW and prior ones as well. Of course it's all in Japanese and I'm reading only on the train when commuting... so it'll be awhile.

Anyway I have seen the 2.6l reciprocal engine calculation by both rotarygod and in the article, but the whole situation seems to be much more complicated than that.

ALSO far as boost goes, why reduce the compression ratio? What rotarygod has said does make sense... what the engine "sees" is the effective compression ratio and as such higher compression for off boost power isn't a bad thought...

The 13B rotary engine has the same theoretical displacement as a 2.6L 4-stroke piston engine, that is it displaces 1.3 litres of air per engine revolution.

The Renesis however, appears to have a higer volumeteric efficiency than a typical N/A piston engine, in the range of 85 - 100+ %. See my practical mass air-flow tests on my other thread http://www.rx8club.com/showthread.php?s=&threadid=33370 to see what the actual mass air flow is through the rev range of a Renesis at WOT.

Displacement is not black magic. These engines (piston and rotary) are mearly positive displacement air pumps that flow a certain volume of air for every crank/eccentric shaft revolution.

Cheers,
Hymee.

Hymee, no one was talking about displacement. Did you ever see that word in my post? I was refering to the overal operation, engine cycle and internal pressures... not to mention anything else of interest that I gleen from the article. Don't jump the gun. I may be posting in a week that in the end that it looks like the Renesis would have to be rebuilt to take boost. I'm still reading. I just said that at this point it looks like there is more to the situation than simply comparing engine displacements.

We have a blow-by cut-off seal in the Renesis, but not in the 13B-REW. All the seals are as thick or thicker than in the 13B-REW. Material is the same or better (?) There's all kinds of good info to come...

Basically I'm saying that a 2.6l recip. engine isn't a 1.3l rotary even if displacement is the same. The combustion chanber is obviously different... t&l spark plugs, lack of valves, different seals, different pressures... a lot of differences. combustion still works the same, but the conditions under which it takes place are quite important as we all know.

Japan8,

It is cool. I wasn't flaming you or arguing with you.

Yes, there are many differences. In essence the thing flows a certain mass of air per revolution. That mass of air has an energy/power associated with it.

Cheers,
Hymee.

Hymee, no prob then. Just sometimes you post something here and then the whole world wants to flame you.

It is true that is is hard to read emotions into posts. Emoticons help. If I was disagreeing, I would state it.

Lots of self proclaimed experts get on here and seem to have a point to proove. If I think I know something I am game enough to state it. If I don't know, I try to ask and learn. This should be a place for sharing and leaning. Inevitabley, people will disagree, but it should be kept honorable.

Cheers,
Hymee.

I agree 100% with you Hymee. After some reading I might have some brilliant breakthorough, or maybe a setbac, but either way I'll know more than I do now.

Man I havn't visited this thread in awile. The heat is still here. pun intended. I must start with my opinion of the effective displacment of the Rx8. It seems to my virgin eyes that it is the equivalent to a 3.9 liter 6 cyd engine.
Is there something I don't see?? It has 1.3 l. disp. and rotates three times per output shaft rev. Since it is still an Otto cycle engine of four strokes then presto every two revs there are six firings, right?

Now here comes the biggie, everyone on the site is going to rag on me for this. It is less efficiant than the equivlant six cld with poppet valves. Why do I say this? because a 3.9 L of standard design would have no problem making 300 hp in street tune.
Not that the rotory doesn't have things going for it, it's just that there is only one small company working half heartedly developing it.
If it were a four valve hi po engine it would make 100 hp per liter. In Hondas case more. Or dare I say the word Ferrari. What is the current output of their 3.6 L V-8? dare I say over 400. NA. Weighs more then the Rx8 and is a 12 sec. car that can do 190 mph. The big difference is the $135,000 extra. You get what you pay for. Lucky for you there are deminishing returns. So you get one hell of a car for really little scratch with the Rx8.

I can say that because I've had at least one Ferrari in my garage for the last 35 years. Along with one of everything else at one time or another. So when I think that the Rx8 fits in my garage there's gotta be some reason.

So together we shall overcome. I will get you an FI system that you don't have to defend roots or screw. There will be a new kid on the block.

I've lost my way, I think I was going to offfer some different opinions from some posts but I forget. You probably didn't want to hear what I had to say anyhow.

Richard

Richard,

In displacement terms it is equivalent to a 2.6 litre 4-stroke. The rotors only turn at 1/3 shaft speed. Although it is a otto-cycle, the firings are more like a 2 stroke. But we don't need to get into an argument there.

For each turn of the crank (eccentric shaft) 2 of the rotars would have gone through 1/3 of their cycle (i.e. one chamber)

To summarise, the theoretical displacement is 1.3 litres per engine revolution.

At 9,000 RPM I measured the actual mass air flow at 225 grams/second at WOT and full load.

Cheers,
Hymee.

Yep that's it. A typical 4 stroke engine completes all of it's cylinder firing within 2 revolutions. It takes the rotary 3 revolutions to complete all 6 chambers.

Well I guess I read that one wrong. I can count that high I'm sure. I will go over it again, not that I disbelive you it's just that I want to see how I could have not understood.

We can all agree that it must be whoever wrote the explaiation that is at fault here. Otherwise this will be two mistakes in one week. And the joke is thats all that is public. If you only knew what I've done in the shop.

I was just joking about whoever wrote the explaination but I just reread it and Mazda's explaination sucks. It doesn't sound anything like you guys explain it. They just basicly show a four cycle cycle. If that makes me clear. I mean their drawing says nothing about the ratio to the shaft. So I can see why I got it wrong. Exactly the ratio stated 2 to 3. 2.6 vs 3.9. I refuse responsability.

Just joking guys. You would think after all the years the thing has deen around I would have taken more interest. But Wankel had many other designs. One or more of them for air compressors. About 15 years ago Holley built some prototype superchargers of a wankle design. I had one but donated it to someone for his supercharger colection. Shouldn't have done that, I also gave him a multistage centrifugal I built around 1979. Shouln't have done that. Anyway the Holley thing had a vane and a slit tube. If anyone knows what that is called. I can't explain it, I can picture it but don't know what say about it.

Richard

Most of the questions left slightly unanswered would be levied if I could get that damn damn damn Yamamoto's book...

Japan8, what's the compression ratio of the RX7 engine? I guess it's lower than Renesis, is it not?

And in term of air consumption, the Renesis behaves a bit like a 2.6L piston engine, exactly for the reasons Hymee has exposed here.

So : who's got The Rotary Bible on his shelf?

What does the compression ratio fo the ancient ass gen3 have to do with the new high tech Renesis? What about the seals and ports... they certainly weren't the same. The two engines sound REA comparable to me...

Reread above... I agreeed with Hymee in the end. in terms of air consumption the 13B is like a 2.6l 4.

Originally posted by Japan8
What does the compression ratio fo the ancient ass gen3 have to do with the new high tech Renesis? What about the seals and ports... they certainly weren't the same. The two engines sound REA comparable to me...

Reread above... I agreeed with Hymee in the end. in terms of air consumption the 13B is like a 2.6l 4.

Hi Japan8,

The only part of my post directed to you was the line about the compression ratio, not the rest.

Peak combustion pressure is related to compression ratio. The current CR of the Renesis corresponds to a given peak pressure that dictated some of the hardware dimensionning and materials. Boost will increase peak pressure and therefore might stretch the resistance of some parts beyond their designed limit. Detonation is also a big issue when peak pressure increase.

As it is turbocharged, I'm expecting the Gen3 rotary CR to be around 2 to 3 points lower than the Renesis CR.

2.6L in a single, twin, 3, 4, 5, 6, 7, 8, 9, 10, 12 cyl or whatever :) They all consume 1.3L of air per revolution like the 13B. Their firing intervals and torque fluctuations differ. Not trying to fight or argue, just extending the discussion. :)

IKN,

Just some more info to consider... The rotors and eccentric shaft in a 20B 1400HP 6.99s ET 201.5 MPH drag car can handle the forces, and they are "stock". And it doesn't get rebuilt in-between runs like a Top Fueler. The apex seals must be special though. This is going to be our downfall perhaps, in relation to their resistance to detonation. I guess we will have to waste and engine before we know the limits! All part of the process of determining what is reliable and what isn't. It is not going to be an overnight development!

I'll have to check my RX-8 book - it details the developments of the seals through the ages. I might be able to check that CR thing for you as well.

Cheers,
Hymee.

Mazda had gone from the 6 port engine in the 13B 6PI to the 4 port engine in the FC because all JDM models were turbocharged. W‚ˆen turbocharged, intake timing is early and flow rate (velocity) is different.


Apex Seal
13B-REW
2mm thick/ 3 piece
material/ cast iron

Renesis
2mm thick/2 piece
material/ cast iron

Side Seal
0.7mm thick
perpendicular cross section
material/sintered iron

1.2mm thick
trapezoid cross section
material/sintered iron

Corner Seal
Rubber plug

Cast iron plug
DLC (Diamond-like Carbon) coating

Blow-by Cut-off Seal
N/A

material/ductile cast iron

Hi Japan8,

As it is turbocharged, I'm expecting the Gen3 rotary CR to be around 2 to 3 points lower than the Renesis CR.

actually only 1 point: it was 9.0:1, just like every other turbo wankel motor Mazda's ever produced (AFAIK, someone might come up with a freak trivia answer and prove that wrong, but i doubt it).

Some would argue that is 10 points :eek:

actually only 1 point: it was 9.0:1, just like every other turbo wankel motor Mazda's ever produced (AFAIK, someone might come up with a freak trivia answer and prove that wrong, but i doubt it).

The '87-'88 Turbo II compression was 8.5:1. The '89 and on turbo rotaries were all 9.0:1. Even the '84-'85 Turbo 12A 1st gens in Japan were 8.5:1.

Hymee, If you tried e mailing me I still don't get any, havn't for 10 days. out works in, negative. Use PM or??

Richard

actually only 1 point: it was 9.0:1, just like every other turbo wankel motor Mazda's ever produced (AFAIK, someone might come up with a freak trivia answer and prove that wrong, but i doubt it).

Thanks,

I found some data in SAE paper 900036 ('90 MY 13B T/C with single turbo).

- The previous NA version of the 13B was 9.7:1 CR ('84 MY)
- The single turbo version is 9.0:1 CR ('90 MY, was 8.5 on '86 MY)
- Boost pressure is as follows (approx) :
> 60 kPa at 2500 rpm
> 50 kPa between 3000 and 5000 rpm
> then going down : 30 kPa at 7000 rpm

The paper also says that detonation was a real issue and that an improved knock control had to be fitted on this engine.

The figures about in line with low pressure turbo versions of Saab, Volvo... although these vehicles are a decade newer and might have benefited from more advanced electronics.

I don't think the rotary can sustain higher boost than its piston engine counterparts. Nevertheless, it would be nice to get the same info about the last generation of twin turbo RX7.

PS : I found 4 SAE papers on older rotaries accessible to all, on a website. Should I put the URL on this forum?

You sir know nothing about supercharger integration. I'm ready to cede my username to you if you wish...
Really?? Then how did 5 hours in my garage at home on a Saturday net me 70 more rwhp with nothing else than swapping from a roots blower to a twin-screw (380rwhp --> 450rwhp)?? Same boost and the twin-screw was dynoed in 105+ degree weather when the roots was dynoed in 80ish degree weather so there may be more of a difference. You do not need lower compression numbers if you stick to moderate boost. 6psi will raise 10.0 to roughly 14.0 at peak boost. In the renesis this will be perfectly acceptible since only the apex seals are at risk. Boost won't pop those, instead detonation will. That is because detonation will exponentially increase the pressure the seals have to take.


Remember- at 14.5psi and 695 cfm, the Eaton 112 consumes 84HP at 13000rpm. The Kenne Bell Twin
Screw uses only 58HP (30% and 26HP less)

I posted my feelings about this on the other thread.

On topic: Companies can produce the supercarger easily, but the necessary mounting hardware will need developement. I believe there are guys trying roots applications so all you would need is their hardware and a twin screw to slap on in the roots blowers place.

Here is what you said and we're arguing about : just bolt a twin screw in lieu of a roots on an aftermarket kit.

Here is what you actually did : bought a full twin screw based KIT for a OEM supercharged engine.
This KIT includes (copied from Kenne Bell's website) :
• Kenne Bell OPTIMODULE to reprogram fuel, spark and trans**
• Kenne Bell Quick Shift Valve to improve shift firmness.
• BOOST-A-PUMP included.
• All Parts inlcuded in kit.
• Best engineered kit.
and as I can see on the pictures, it also include some adaptor pipes on the intake and the exhaust.

Do you think it'd take just 5 hours to design this kit? I don't think so... And it's certainly not what I'd call just slapping a twin screw on in the roots blowers place'.

You lied, you still deserve the comment!

Here is what you said and we're arguing about : just bolt a twin screw in lieu of a roots on an aftermarket kit.

Here is what you actually did : bought a full twin screw based KIT for a OEM supercharged engine.
This KIT includes (copied from Kenne Bell's website) :
• Kenne Bell OPTIMODULE to reprogram fuel, spark and trans**
• Kenne Bell Quick Shift Valve to improve shift firmness.
• BOOST-A-PUMP included.
• All Parts inlcuded in kit.
• Best engineered kit.
and as I can see on the pictures, it also include some adaptor pipes on the intake and the exhaust.
I just bought the twin-screw used without all that extra crap from a guy in califorina, so don't accuse me of buying that crap. My valve body was ordered from an entirely different vendor months before I got the blower. My tune was done on a dyno weeks after I personally installed the blower. The BOOST-A-PUMP is snake oil and I would never use it, instead going with twin 255lph fuel pumps (got money you don't know what stock is and don't look it up). There are no aditional pipes for the intake or exhaust. Exhaust being impossible because a twin-screw has nothing to do with the exhaust (but you knew that right?).

Do you think it'd take just 5 hours to design this kit? I don't think so... And it's certainly not what I'd call just slapping a twin screw on in the roots blowers place'.

You lied, you still deserve the comment!
I'll post pictures when I get home in 3 hours of me litterely pulling off the old blower and using all the OEM gaskets/bolts/hardware to put a knew one in its place. 5 hours to swap. In the 8's case, the roots manifold may need to be slightly modified in order to accept a different bolt pattern (which any decent metal worker can do). The way the pullies are driven are the same and where they sit are the same. If one fits, the other will be able to very easily as I said before. But since you think a roots blower would effect exhaust I don't know why I'm having this convo....

I have no reason to lie to you guys since I want to see these things run some decent times with decent dynos. My knowlege is based in blowers and nitrous and I will suggest what I think is best for the application because I don't want a blown motor as much as the next guy.

I just bought the twin-screw used without all that extra crap from a guy in califorina, so don't accuse me of buying that crap. My valve body was ordered from an entirely different vendor months before I got the blower. My tune was done on a dyno weeks after I personally installed the blower. The BOOST-A-PUMP is snake oil and I would never use it, instead going with twin 255lph fuel pumps (got money you don't know what stock is and don't look it up). There are no aditional pipes for the intake or exhaust. Exhaust being impossible because a twin-screw has nothing to do with the exhaust (but you knew that right?).

I'll post pictures when I get home in 3 hours of me litterely pulling off the old blower and using all the OEM gaskets/bolts/hardware to put a knew one in its place. 5 hours to swap. In the 8's case, the roots manifold may need to be slightly modified in order to accept a different bolt pattern (which any decent metal worker can do). The way the pullies are driven are the same and where they sit are the same. If one fits, the other will be able to very easily as I said before. But since you think a roots blower would effect exhaust I don't know why I'm having this convo....

I have no reason to lie to you guys since I want to see these things run some decent times with decent dynos. My knowlege is based in blowers and nitrous and I will suggest what I think is best for the application because I don't want a blown motor as much as the next guy.

By intake / exhaust of the SUPERCHARGER, I mean inlet / outlet.

It seems I've been a bit hard on you : so the Kenne Bell S/C has exactly the same bolt patterns, flanges and dims than the Roots??

It seems I've been a bit hard on you : so the Kenne Bell S/C has exactly the same bolt patterns, flanges and dims than the Roots??
Close enough as far as bolt patterns. The roots style blowers sit on a custom intake manifold which can be easily swapped between roots and twin-screw blowers. Even if the manifold was the adapting problem, the rest of the kit would be perfectly interchangeable with is key. An adapter can be made by anyone with metal working skills. It's the pulley, belt, intake design you could transpose between kits with no modification. Both blowers draw in air the same and spitit out the same, it's the innards that are different.

Pics...

What I got-
http://members.cox.net/drewaz/KBonTable.jpg

Before-
http://members.cox.net/drewaz/BeforeKB.jpg

During-
http://members.cox.net/drewaz/DuringKB.jpg

After-
http://members.cox.net/drewaz/AfterKB.jpg

People have had to re-drill some mounting holes on blowers in order for them to mount up properly. Not that bad of a swap. :)

Drewstein,

Quite transparent! I'm sure you're dealer wouldn't notice a thing if they had the car for a service!

I don't think ANY form of forced induction is going to be considered a "stealthy" install, IKN.

I don't think ANY form of forced induction is going to be considered a "stealthy" install, IKN.

I was not being sarcastic. On this Lightning, I think the S/C swap is very discreet.

Drewstein,

Quite transparent! I'm sure you're dealer wouldn't notice a thing if they had the car for a service!
Well I don't trust anyone with my vehicle, including the dealer. I do all my own service and work in order to avoid stupid lot attendents or mechanics from touching my baby. I learned how to service my buddies RX-8 so he can mod with pleasure and not worry about stealership problems. People at car shows think it's the stock roots blower that was polished and several mechanics asked me if it was supercharged.

On the 8, we want to modify the stock plastic to conceal the twin-screw so people will have no clue. Picture the intake filter up front running straight back up to the throttle body and intake plenum, that keeps running straight back to the blower inlet where it curves down and connects. It would sit completely over the blower almost hiding it, but if we trim the plastic properly, maybe we can mount it up to the sides of the blower and over the motor. Top secret blower unless you know what to look for. Just waiting for the kits to come out and we're sold! :D