Why roots-type Eaton?
 

By the looks of the pictures at brperformance and Jackson Racing, it appears to be an Eaton blower. While I love the roots-type Eaton supercharger I have in my Grand Prix, I wouldn't make it my first choice. I've hit Jackson Racing's site a few times and having been too impressed with their prices either.

From the pictures, the way the SC mates with the manifold, designing and installing an intercooler would be a PITA. You'd run into the same problems I have trying to IC my Grand Prix. . . I'm short $2000. Because of the space constaints a liquid/air IC would be about the only option. While often more effective, it's also more costly.

I'm thinking of going the turbocharged route once I stash enough cash, learn more about the ignition and fuel systems, and figure out how to squeeze everything in. But if I were to Supercharge, I'd look into a Vortech or other centrifugal SC. Better adiabatic efficiency --> less parasitic loss and temperature differantial. It'd also be easier to intercool.

PseudoRealityX - Why wouldn't SCs like Cold-air intakes? Other than water ingestion of coarse, but engines don't like that either. Water injection, however, is an other story.

Short runners vs. long runners - short just becuase the long ones don't make a difference. If you pressurize an engine that already has long runners you won't run into any problems, just a bunch of lost space and extra material.

Cool, thanks for clearing that up! Differential pressure between the input and output of the SC affects performance significantly. So I now can see how the intake tract can hinder performance. However, this shouldn't be affect a root-type blower as much as it would a centrifugal, since the roots-type is a positive displacement compressor and less affect by differential pressure. Also, keep in mind, with the amount of heat generated during compression, the colder air the better (especially w/o an IC). Problem is finding the lesser of the two evils. :dunno: Once option would be an oversized intake pipe. Another would be a large box for the filter.

I don't think that graph is a fair representation of a centifugal SCs capability. An S2000 has no low end to begin with. . . everything is up top. You can also play with gearing a bit, to get more pressure near the low end. Redline is well before the 8,000-9,000 RPM range, so the SC gearing can be tuned for a smaller RPM band. Spooling is not as bad a common turbo applications.

I don't recall the manufacturer, but I was at a car show last summer and there was a motorcycle with a turbo. The intriguing part of the turbo was that it had variable vanes and casing. This allows the compressor to be optimized at various RPMs.

The grass is always greener on the other side. . . as I mentioned before, I already have an Eaton. Incredible amount of torque, but little up top (well, at least before my last mod ;) ). My friend raced a C5 last week. His car is nearly the same as mine and only about 0.20 seconds slower. The vette had a better launch and started out ahead, but my buddy was able to make up the difference and pass. At the end of the track, the vette started pulling on him and crossed the finish line first. Something similar happend to me last year against a Grand National, except I got spanked severely at the second half of the track. :crying: So do you see why I'd like more up top?

Sounds like your both right. :) Centrifigal superchargers are peaky, but that sounds OK for GNO's application. On the street however, you will lose lower RPM power in order to gain the higher RPM power from the centrifigal supercharger. It works if you have an application where you can spend a lot of time at the high end of the tach. A centrifigal supercharger has two major disadvantages to a turbo, both having to do with being driven from the crank. First, it's not as efficient as a turbo, because the turbo is using lost power from the exhaust system to drive its compressor while the centrifigal supercharger steals power from the crank. Second, since the centrifigal supercharger is driven directly from the crank and must operate at very high speed to develope its boost, it doesn't have the same flexiblity as a turbo in terms of tuning for lower RPM power. If you gear it low enough to make power at lower RPM, it will spin too fast and produce too much boost at high RPM. Since the turbo isn't directly connected to the crank, you can use a wastegate and blowoff valve to help with these problems.
VNT turbos are awesome, similar to VTEC tecnology for the valvetrain, by allowing for tuning for peak efficiency at different RPM's. When more manufacturers start to use these on stock cars, so more reasearch is done and the price drop on production, the power gains from turbos will be even more amazing.

I totally agree. The roots-type does have better street manners.

Since Eric F mentioned how the centifugal is more peaky, another point came to mind. Torque and trannys - horsepower doesn't kill trannys, torque does. As I mentioned in my first post on this thread, I've been thinking of going the turbo route for my wife's Protege5. Although a turbo doesn't offer as much off the line, after a shift, there could be some serious torque hitting the pavement. Depending on how stout the tranny is, survivablity may be a concern.

Another problem I currently have is minimizing wheelspin at launch. The wicked low-end helps to do some nasty burnouts, but launching has become a bit of a problem for me. At my last trip to the track, I noticed every 0.10 second on my 60' cost me 0.20 second on my 1/4 mile ET.

As much as I'd like to, it's hard to have sympathy for your traction problem. ;) At least until I can achieve that same problem. :(

Sport Compact Car did a series of articles called "Suck, Squish, Bang, Blow". I kid you not. The articles were very good and started basic with information about a 4 stroke engine and worked their way up to forced induction. The two forced induction article were in the 7/01 & 9/01 issues. I recommend reading them if you are contemplating forced induction. They give a good comparison of the strengths and weaknesses of the different types.

SCC is so much better than the other Import mags. I picked up one of those two issues. Overall a well written article. IIRC there was one technical issue I didn't area with. I'll have to take a second look.

That why I've been a subscriber for several years. I keep the back issues for reference material. :D