Roots Supercharger For Our 8's
 

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!!

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.

And Blitz and Kinght Sports.

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.

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

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?