Carl Fausett

Several of you have written me to ask how my winter project of supercharging the 16v early 928 turned out. Well, Wednesday was clean and sunny here in Wisconsin. I got my 78 928 out for the first time since installing the supercharger on it. Before I put it away for the winter, I took some measurements: 1/4 mile in 16.2 seconds and 196 horsepower. Now, same car, same exhaust system, ignition system, driver, weight, EVERYTHING, (even the same measuring devices), recorded a 1/4 mile in 13.6 sec and 320 horsepower. My 0-60 time was 4.98 seconds. This is with manifolds and a cat-back Borla exhaust system on a 78 928 Euro 5 speed. The manifolds and the single exhaust are my next problem... under full boost (9 psi) with the driver side window down I can hear this HUGE whooosh sound coming from the Borla where last year there was a nice rap to it. Now the air can't pass thru the lil' 2 1/2" single exhaust fast enough. MSDS headers and a 3 1/2" tubing exhaust system are on their way... what do you s'pose the gain in HP will be with that?

John V

Exciting results. Please share the details of the install.

Luke

320 WHEEL POWER! wow Did you have to make any fuel accomodations? How is that CIS?

Flint

Holy hell. You know, I didn't have any interest in supercharging my own car, but now I know it can be done to a 16V Euro...hmmm, I already have the racing cams...

Flint, '84 Euro-S, A/T

Jack 1984 928

Flint where did you get your racing cams? Are they stock euro spec or what? I am planning on douing the euro heads and intake throttle body next year sometime. Carl would you be intrested in selling your brackets or just the specs so as to have another machine shop make someone some?

Aaron Rouse

Flint, an 84 Euro can use the FAST kit. FAST actually told me that it(84 euro) was one of the more easier cars to get the kit to install on. The person there claimed to have owned a 84 Euro and had a Vortech on it, but then was in the process of going to a stroked 32-valve motor in that car when I talked to him.

John Anderson

We have an S4 in the shop right now for a supercharger setup. We''l keep you guys posted on the results...we should begin rolling the dyno in a few weeks.

The kit will run the stock intake (so , far there seems to be no problem), the stock intake manifold and will retain all stock components on the motor. It will be a centrifugal blower, with a set of our custom chips to provide the fuls and timing...possible injector upgrade might be needed.

We've strapped over 100hp to the wheels on the 944 series, our hopes are up on this kit!

Again, we'll keep you posted.

Carl Fausett

Thank you for your kind remarks. This car is FUN to drive now! Boy! I can barely keep my foot out of it. Anyway, Here are the anwers to some of the questions I have been getting:

Did you have to do any modifications on your vacuum lines? Not really. I did modify my oil filler-to-air box hose tho, ran that to a catch tank and I suck off the vapor with a vacuum line.

How is your CIS handling the boost? Very, very well with no modification, only a little tuning.

Where there any necessary modifications to the CIS? None. The CIS the 928 used is the same one Mercedes used on their turbo'd cars and Porsche used up to 1996 on the twin turbo Carrera. This CIS can fuel up to 450 HP. No problem.

Did you make an extra mounting bracket? Several. The torque load on the blower under full boost at 6,000 RPM calculated to 82 lbs of pull. We built our blower mounts to hold her still to about 140 lbs of linear pull just to be on the safe side. I used an spiral-wound self-adjusting idler pulley to provide the belt tension, and I have now figured out that is too fancy and it makes changing the 6-rib blower belt a pain. I am going to replace it with a garden-variety blower idler tensioner pulley with an eliptical mount.

Did you have a custom pulley made for the
supercharger? Yes. Took the supercharger pulley pulley for a 5.0 liter Ford and the 928 stock pulley to a mchinist and we figured it out. Cost me $350 to have it machined out of a single 6061 Aluminum billet.

My AC was shot on this car, so I was able to put the blower roughly where the air cond compressor was. But, I don't have AC anymore. You may not want to do that. I felt that AC in Wisconsin was somthing I could do without, and when I am performance driving, I'd have the AC off anyway.

About selling the plans or specs: I never thought about that. I'd have to take all the parts off the car and mic them up for you and CAD/CAM them and stuff. Quite a task. That wasn't my plan. There are guys in business (FAST of Texas, Projekt 928.com, etc.) to do this for a living, that's not me. Still, I'm thinking about it. I wouldn't want to make parts, but plans, maybe...

Carl Fausett

I should add one BAD thing that has happened since the supercharger install (allright, two.... but my sons 82 in a 55 zone ticket doesnt really count) - my brand new clutch is slipping. Last summer in mid-autocross season I was forced to replace my clutch as I couldnt nurse it along any more. I replaced EVERYHTING (and it wasnt cheap). Two friction plates, the intermediate plate, the pressure plate, throwout bearing, pilot bearing, fiork, the WORKS. Love that twin-disk clutch - truelly a superior design. But now - that clutch is only 6 months old, when I am going from 2nd to 3rd and my boost is up there, that clutch will slip for a good 2 seconds if I wood it. I can't believe it. My son couldn'tbeleive it- he helped me put it in.He's sitting next to me and says "was that your CLUTCH slipping?!?" Shoot. And since the Marc Anderson and Company retrofit the early twin-disk clutch into their stroker built 6 liter 928s to handle the power, I don'tknow where I am gonna go with this.

2V4V

Flint,

Do keep in mind that part of the reason the Euro makes more power than the US version is the much higher compression ratio of the euro model.

While this does not preclude forced air induction, it makes it a trickier proposition than on a car running in the 8:1 - 9:1 range.

There are a couple schools of thought on forced air induction and rather than type a 30 page condensed version, I would suggest reading "Street Supercharging" by Pat Ganahl. A relatively thorough intro to forcing air into your motor, available at your local McBooks-JumboStore for about $18.95.

Also, without going into a boatload of tech, cam optimization is very different from NA to SC cars. In short, the cam that helps a normally aspirated car perform better, will not have the same effect on a forced-air car. If you get a chance, compare the specs on a 944T cam with those of a 4.7L.

HTH,

Greg

Aaron Rouse

Quick Carl, I talked to a owner of a twin turbo 78 awhile back and he mentioned he knew of someone that could make a custom clutch for the 928, I think out of ceramic(I might be way off on that though). Anyway, I still have his email and if you like I could try and get more details.

Carl Fausett

Thank you, Aaron, I would love it. Looks like I am gonna need a beefier clutch.

BTW: I disagrre with another post that says that the Euro's make more HP cuz of a higher compression ratio. All my Porsche stuff says that the 78/79's USA and Euro are 8:5 to 1 compression ratio. I specifically selected the early (78, 79) 928 for my supercharger cuz I can run more boost without detonation than the 10:1 compression ratio boys.

It is my understanding that the 40 extra HP that the early Euros got over the USA counterparts were as a result of pollution control in US in 1978/79. The Euros could run more agressive cam love durations, no smog pump, and no catalytic converter.

Aaron Rouse

I will let you know what I find out about the clutch.

I think that post in regards to the Euro motors was more in regards to the 84 models such as mine and Flints. Where we do have higher compression than the older models that you just described.