Here´s the Blitz SC for AT or M transmission. Blitz has no spec or info on the kit on their site, but I seem to remember the number ~50hp. For me, that´s 50 expensive hp... I´d rather go for a TC today.
(Hopefully this aint no repost)

http://www.blitz-uk.co.uk/2003/bookeeperpics/SUPCHRG.jpg

Is this kit actually out yet? I saw an ad in a magazine that said "coming soon in 2005" or something like that.

It´s on Blitz website inkl price and everything... but no furher info.
www.blitz.co.uk

I think you mean http://www.blitz-uk.co.uk/

No avail date as of yet, they have delayed the release of the charger for the 8 for over a year now due to one reason or another. Not holding my breath for early 05.

That is one damn tiny roots supercharger. Don't plan on raising the boost on that thing.

Yeah, thats pretty damn small. A 50hp gain? And its like what? $7k? No thanks.

they use the same picture for all their kits, even the twin supercharger lexus 430 kit.
They list the 8 kit at 3750 pounds sterling or well over 6000USD. And I agree with RG that looks like a eaton 62 which isn't going to boost this engine by much.

Now you have to give credit if they are supplying a $1250 electronics package. Man I sure hope someone can do better then that real soon for my kit. That little add on kills the sales price and they get all the profit. Electronics don't cost shit to produce. They have research but so does everyone else.

U.S pricing never correlates to UK pricing so that is not really reflective of what we should be paying. Take the car itself for example. The 8 lists base for 20k in pounds which is around $37k US. Not exactly what I paid for mine.

wow...that's a lot of money if you can only take it to that level and no futher:( bu tat least you can' tactually find kits out for the 8 now:D but dang..teh greddy kit is a whole lot less money adn it's supposed to give you 60whp not 50:( for the price of teh blitz you could get the greddy and have it installed. ah who am i kidding i ca't afford either:( lol

Dammit soon as i see these kits in the flesh and a bit of a history i will want!!!

Greddy would be nice as prefer a turbo over a super!

Hmm---what are the benefits that you guys see of a turbo over a super--modibility? I know turbos respond more to mods. I've owned both turbocharged (93 RX7) and supercharged (Millenia S) and while those two cars are apples and oranges--I never saw a difference in the power delivery. The RX7s twin setup reduced lag it was still there--while the Millenia S has a linear power delivery. Of coures there is hundreds of pounds of weight difference and about 70HP difference between my two though.

I see benefit in whichever comes to market first. Until then it is all speculation on vaporware.

...Hmm---what are the benefits that you guys see of a turbo over a super--modibility?... One of the major drawbacks to an SC (of any type) is that it is locked into the engine rpm, and so it's efficiency band is rather narrow. In this case, the standard Renesis engine with it's large rpm range exagerates that limitation, so a turbo would offer a broader power band.

For example, check out the dyno results of an S2000 with a centrifugal SC. The SC actually hurts performance in lower rpms, has only modest increases in the middle rpm band, and doesn't really "kick in" until the upper rpms. While this is acceptable in a road course race track, or during "canyon carving", where you will always have the car in the upper rpm bands anyway, this is perfectly acceptable. But for around town driving, this will actually make the "gutless" feel of the engine at low rpms even worse. It depends on what you're looking for, but it can be very disappointing to spend all that money for "peak" power, and actually have worse performance around town. While one might not have "turbo lag", they will have "rpm lag", which can be just as frustrating, and is something that you have to work around just as much as turbo lag.

Meanwhile, a turbo can "cover" that rpm range better. It is still affected by the greater rpm range (for example, a turbo will have to pump about twice as much volume of air at 8k rpm, than at 4k rpm, to maintain the same boost level, so one will need to size accordingly), and there will still be some trade-offs in response vs. peak power, but not quite as much as with an SC.

But at the same time, the lower rpm limit of the auto-Renesis might make it more feasible for a roots-type SC, which while it has some drawbacks, is still quite effective in the 7k rpm limited Miata. And the lower rpm boost that the roots type gives will make up for some of the lack of low end grunt of the Renesis.

Anyway, I would choose turbo vs. centrifugal SC vs. roots SC vs. other upgrades on what I wanted out of the car, and for my money. While there are cases where one of the SCs would be fine, a turbo seems to be a better fit for the RX8 in the majority of cases, including peak HP and broad power band.

---jps

ahh i can sense rotarygod is gonna chime in on this one. For the differences there have already been a whole lot of posts comparing the two different types of fi and even a lot of talk abou the different types of turbo setups and kinds of superchragers. i prfer to read what rotarygod, richard paul, charles h hill, mazdamaniac, and Hymee (can' tremember the others off the top of my head sorry guys) have to say as they are very knowledgeable singularly..but together they are an outstanding source of performance info. i'd do some searches you'd learn a whole lot in one afternoon:D

No one ever mentions the benefits of weight or placement.

Having seen the Greddy in person and the Blitz in enough pictures, the Blitz looks like it would take half the time to install (and remove) while the Greddy would place the turbo and weight of the kit down low near the engine which is good for weight but might take a bit more work for a diy. Just a small sidenote from someone who likes to do their own work.

One of the major drawbacks to an SC (of any type) is that it is locked into the engine rpm, and so it's efficiency band is rather narrow.

I could write several pages on how that's not necessarily true. I could also write several pages on how a turbo also fits in a relatively narrow rpm range.

And I could write the sidebars.

and all i could do is agree b/c they know a hellova lot more than i do:p

Basically I would write it in several thousand words and get overly complex and then Richard would come along and sum the last 2 hours of my life spent typing into about 3 sentences.

LOL i love it when that happens....now i just skip to his post and sum it up....rotarygod you make my eyes hurt...adn my brain turn to mush..hehe i wouldn't have it any other way;)

So we all know that you love the Racing Beat intake RG, but what turbo or sc really catches your eye?

I am going to wait until mid next year before I consider the FI option.

By that time there will probably be 3 systems on the market all with consumer feedback on how they work.

I'll buy the best one at that time in June.

So we all know that you love the Racing Beat intake RG, but what turbo or sc really catches your eye?

It really depends on your goals. I am really only truly against centrifugal superchargers such as Sunflower Mazda's. The ones I am most anxious for are Richard's Axial flow unit and Hymee's twin screw supercharger. I'm not a fan of the Blitz system. Turbos are pretty generic. Any system from STS, SSR, or PTP should also be nice. Depends what type of power you want and what type of driving you do the most.

But it's such a CUTE lil roots supercharger! :D

I think this blitz system is a weak attempt... way overpriced for what it allegedly delivers. Not to mention it just gives me a bad feeling. Gut feeling can be very useful!

RP's is much more intriguing.

One of the major drawbacks to an SC (of any type) is that it is locked into the engine rpm, and so it's efficiency band is rather narrow. In this case, the standard Renesis engine with it's large rpm range exagerates that limitation, so a turbo would offer a broader power band.

For example, check out the dyno results of an S2000 with a centrifugal SC. The SC actually hurts performance in lower rpms, has only modest increases in the middle rpm band, and doesn't really "kick in" until the upper rpms. While this is acceptable in a road course race track, or during "canyon carving", where you will always have the car in the upper rpm bands anyway, this is perfectly acceptable. But for around town driving, this will actually make the "gutless" feel of the engine at low rpms even worse. It depends on what you're looking for, but it can be very disappointing to spend all that money for "peak" power, and actually have worse performance around town. While one might not have "turbo lag", they will have "rpm lag", which can be just as frustrating, and is something that you have to work around just as much as turbo lag.

Meanwhile, a turbo can "cover" that rpm range better. It is still affected by the greater rpm range (for example, a turbo will have to pump about twice as much volume of air at 8k rpm, than at 4k rpm, to maintain the same boost level, so one will need to size accordingly), and there will still be some trade-offs in response vs. peak power, but not quite as much as with an SC.

But at the same time, the lower rpm limit of the auto-Renesis might make it more feasible for a roots-type SC, which while it has some drawbacks, is still quite effective in the 7k rpm limited Miata. And the lower rpm boost that the roots type gives will make up for some of the lack of low end grunt of the Renesis.

Anyway, I would choose turbo vs. centrifugal SC vs. roots SC vs. other upgrades on what I wanted out of the car, and for my money. While there are cases where one of the SCs would be fine, a turbo seems to be a better fit for the RX8 in the majority of cases, including peak HP and broad power band.

---jps

I believe you are a bit off on this. The centrifugal SC (which looks like half a turbo marketed by Vortesh, Paxton, etc.) does make boost in a linear fashion, but the Roots/Lysholm SC's make a substantial amount of boost right off idle. Those are the ones marketed by firms like Jackson Racing, Blitz, Comptech (except the S2000's). This might be a good alternative for the RX8. The turbos usually generate their boost at around 1/3 of the revs (in this case I would expect it to have boost around the 3500 rpm & up range). Usually turbos do develop more hp than SC's because they are driven off spent exhaust gases vs. belt driven off the engine (SC's take a bit of the hp generated to drive the belt to turn the SC), but they are usually a bit more complicated to install, and can be more expensive (though from this Blitz kit...YIKES !), and needs more tuning.

If 60 hp is about the most that the Renesis/RX8 can generate safely it might be a better fit for a Roots, as the kit can probably generate that quite easily, if there is no upside (turbo can turn up the boost). The Celica Blitz unit is priced at $5K on Hop Up racing, but if the RX8 unit really is $7K I would seriously doubt if they would sell many of them. At $5K (and if they could generate 60 hp, not 50hp that they are currently claiming) I would consider it, but at $7K, dont think so.

Still too expensive at 5k for 60 hp.

Need more like 100hp

We need a better ratio of return on investment.

Hell for that price you can port and polish and get 40 hp for less than half the price.

where does it say its 7k? Superchargers tend to be more costly than turbo's but you should be able to save on time and labor.

Just the retail price on many of Blitz's SC kits. They seem to charge a big premium.

I believe you are a bit off on this. The centrifugal SC (which looks like half a turbo marketed by Vortesh, Paxton, etc.) does make boost in a linear fashion, but the Roots/Lysholm SC's make a substantial amount of boost right off idle. Those are the ones marketed by firms like Jackson Racing, Blitz, Comptech (except the S2000's). This might be a good alternative for the RX8. I assume that you are referring to my comment about the centrifugal SC having "rpm lag". I agree that a Roots SC does not suffer from "rpm lag", but you still have to set it up so that it only spins so fast at the rpm limit. And like the centrifugal SC, the farther down the rpm range, the slower it spins, and the less low end boost you will have on a Hi-po Renesis with a Roots SC than you would with a Roots SC on say a Miata (or Lo-po Renesis even). So you will still be compromising the benefits of a Roots and Lysholm SC on a higher rpm engine.

...The turbos usually generate their boost at around 1/3 of the revs (in this case I would expect it to have boost around the 3500 rpm & up range)... My point is that you can't make an assumption like that. The point at which a turbo starts producing positive boost isn't measured at a fraction of the rev limit like an SC. A turbo could be producing positive boost around 2500 rpm on a Renesis just as easily as on a 6k rpm limited 4 banger. Mind you, this all depends on the size and type of turbo you select and other things, but you have more flexibility in designing that with a turbo.

...[turbos] are usually a bit more complicated to install, and can be more expensive (though from this Blitz kit...YIKES !), and needs more tuning... I agree. How much you want to spend in time, money, and effort is a major consideration in making your choice. But there have been other situations where a SC kit is difficult or awkward enough to design that it will start getting expensive (or even impractical in some cases, like the MR2 Spyder).

...If 60 hp is about the most that the Renesis/RX8 can generate safely it might be a better fit for a Roots, as the kit can probably generate that quite easily, if there is no upside (turbo can turn up the boost)... It's not just more power that the turbo has over the SC. At 25% increase of power, the SCs will have to work hard enough that they will show their limitations of either rpm lag or having to set up the SC to spin only so fast at certain rpms. That amount of airflow also means that you only have to make the turbo so big, and if you size it right, you can have it spool up rather quickly, and still have a broader power band than an SC (an exception might be a Lysholm, but that all depends on alot of things).

And turbos also have a side benefit for those of us at altitude like Denver. Like a normally aspirated engine, an SC will only draw in a certain volume of air at a certain throttle/rpm combination, so it will draw in thinner air at higher altitudes. But as long as your turbo is big enough, it will draw in a larger volume of air at higher altitudes to end up at the same boost levels. Turbo lag does increase (and you have to watch octane levels), but other than that, you basically get the same power. For example, if you are high enough in altitude that a NA engine is only making 80% of power in the thinner air, a 250 HP engine will be making appox. 200 HP. A bolt-on SC kit that increases power by 25% at sea level will give that same engine appox. 250 HP at altitude. A bolt on turbo kit (with a big enough turbo) that increases power by 25% at sea level should pretty much give that engine appox. 310 HP at altitude. That's a very general calculation, but you get the idea.

---jps

You're wrong in many places but the one that really interests me is your altitude compensating turbo. :confused: I think you need to move up to some higher math. It is published on this forum more then once. Try searching.

Not only would your system interest me I can name a couple of aero engine mfg that want to hire you. ;)

the blitz supercharger looks the same as the toyota design used back in the 80's (?)
it also looks like the smaller version used on the 1.6L and there was a longer higher displacment on for the 2L.
these SC had straght lobes not helical. they did have a little lag and were said to come on boost 1000rpm from idle. I have heard of people using the 2L SC on 3.6L motors with good results with low boost but if blitz are using the smaller version (which displaces about 1.4L per revolution from memory) I don't see how it can keep up with the rotary's need for air.
one thing they have a clutch on the front of this SC and can turn it on and off. if they over drive it for low rpm then they can turn it off to stop it spinning to fast and damaging it's self.

blitz would have considered all these and i'm sure the kit is half decent.

Well, I've always heard that turbos tend to suffer less from "thin air syndrome" then superchargers or normally-aspirated cars. I thought it had something to do with the thinner air causing less resistance to the spinning turbo impeller however.

jds

You're wrong in many places but the one that really interests me is your altitude compensating turbo. :confused: I think you need to move up to some higher math. It is published on this forum more then once. Try searching.

Not only would your system interest me I can name a couple of aero engine mfg that want to hire you. ;)

And it's thinner coming out also. On top of that it is colder outside and therefore there is less in the way of volume to spin the turbine. No free lunch here.
A variable stator might help but still never gonna get anything for free.

How come they only used SC in WWll on the aircraft. There was one turbo by the Nazis but unsuccesfull compared to SC engines. They did use nitrous though on the fighter planes for hi alt dog fighting. But they couldn't carry enough to use it except in emergency.
Also of note should be that they had an inert gas to pressurize the nitrous to a given press. Not reliying on just the natural press which varies with amount left and temp.

Not aware of any rootsblowers ever used on these engines. There were some tests by Allison for turbos but I don't know what came of it. There were some multi stage centrifugals as on the Griffin. 2222 cu in V-12 Rolls Royce used in some transport planes.

Are we comparing airplanes now?

(sigh).

:)

The thing about a turbo system that makes it appear to work better at higher altitudes isn't the turbo itself but rather what boost level is regulated at. If the wastegate is set to open at 8 psi, it is irrelevant how hard the turbo is working to et there as long as it does. At a lower altitude where the air is thicker, the turbo doesn't have to work as hard to get that 8 psi. As the altitude rises, it becomes harder to get that pressure since there is less of it. The turbo just works harder since the wastegate doesn't work as soon. The wastegate does allow the turbo to still hit 8 psi so it appears that turbos do in fact compensate for altitude. However this is only true to a point. As the turbo works harder to get the same boost it would at a lower altitude, it also heats the air up more so there is a drawback. The same basic mentality is used as an excuse by many people to keep their air filters in the hot engine compartment. They assume that the turbo will just spin faster to make up for the less dense air which is true but it is still much hotter. From this standpoint I will agree that a turbo does have an altitude advantage over a geared supercharger. A supercharger that is geared for 8 psi at sea level will not make 8 psi in Denver. A turbo will but it is also working harder and producing less power than the same 8 psi at sea level. It would still have an advantage but by no means is it a be all end all altitude compensation. There is always a tradeoff.

For street use this is probably one of the only areas that I will rule in favor of the turbo. When it comes to other things such as reliability, heat, etc, I won't.

RG, tell me is the waste gate working in gauge pressure or absolute. It seems to me that they work on gauge pressure which means that if it makes x psi over the ambiant it still does at higher alt.
Thus it is only x higher then the now lower absolute pressure which is what the SC does. +/- that is. Clear as my usual explaination, right.


Prey tell why would you not look to the aerospace industry for advanced engineering. They have alot more money and stricter rules. require more testing and if something fails they cannot get out and push.

You don't know what you're talking about, I read it in Makes and Models so I know its true :D

jds

And it's thinner coming out also. On top of that it is colder outside and therefore there is less in the way of volume to spin the turbine. No free lunch here.
A variable stator might help but still never gonna get anything for free.

How come they only used SC in WWll on the aircraft. There was one turbo by the Nazis but unsuccesfull compared to SC engines. They did use nitrous though on the fighter planes for hi alt dog fighting. But they couldn't carry enough to use it except in emergency.
Also of note should be that they had an inert gas to pressurize the nitrous to a given press. Not reliying on just the natural press which varies with amount left and temp.

Not aware of any rootsblowers ever used on these engines. There were some tests by Allison for turbos but I don't know what came of it. There were some multi stage centrifugals as on the Griffin. 2222 cu in V-12 Rolls Royce used in some transport planes.

RG, tell me is the waste gate working in gauge pressure or absolute. It seems to me that they work on gauge pressure which means that if it makes x psi over the ambiant it still does at higher alt.
Thus it is only x higher then the now lower absolute pressure which is what the SC does. +/- that is. Clear as my usual explaination, right.


Prey tell why would you not look to the aerospace industry for advanced engineering. They have alot more money and stricter rules. require more testing and if something fails they cannot get out and push.
The wastegate is nothing more than a mechanical spring that is set for a certain amount of pressure attached to a trap door. It isn't affected by altitude. It would still take the same amount of pressure to compress it in space or on the moon too. A boost controller, if so equipped, is calibrated to sea level pressure.

While a supercharger will give you say 8 psi over ambient pressure, the wastegate on a turbo will allow you to get 8 psi over sea level pressure.

That's why I asked YOU. Now I concur if it's working off absolut pressure then it will until actual density keeps it from continuing approch it's spring pressure. It's still going to have to work harder though.

Who is Makes and Models?

...If the wastegate is set to open at 8 psi, it is irrelevant how hard the turbo is working to et there as long as it does. At a lower altitude where the air is thicker, the turbo doesn't have to work as hard to get that 8 psi. As the altitude rises, it becomes harder to get that pressure since there is less of it. The turbo just works harder since the wastegate doesn't work as soon. The wastegate does allow the turbo to still hit 8 psi so it appears that turbos do in fact compensate for altitude... That was the point I was trying to make.
...However this is only true to a point. As the turbo works harder to get the same boost it would at a lower altitude, it also heats the air up more so there is a drawback... A turbo will but it is also working harder and producing less power than the same 8 psi at sea level. It would still have an advantage but by no means is it a be all end all altitude compensation. There is always a tradeoff...
I agree with that too. There is always a tradeoff. I was being VERY general in my math, just to show the effect. The turbo will have to be large enough to draw in the larger volume of air required, and it will have to spin faster than at sea level, increasing turbo lag, and increasing intake charge temperatures from both friction and compression. It won't make up for all of the altitude losses, but it will make up for alot.
...How come they only used SC in WWll on the aircraft... If I'm not mistaken, they did use turbos in some planes like the B-24. In those days, and still in some countries, people would/will call turbochargers "exhaust-driven superchargers", or "superchargers" for anything that is boosted. So, you will read about a some bombers being supercharged, when they are actually referring to exhaust-driven superchargers.

---jps

If you look at a "supercharger" on a B-17, it is nothing more than an exhaust driven turbocharger with a very large pilot controlled bypass valve (wastegate). This is how they could just turn on the supercharger at higher altitudes. The pilot also had to manually increase the richness of the mixture. Thank god for modern computers!