FraMac

I'm probably handier with a bottle opener or corkscrew than setting up your timing, but happy to help where I can

Speak soon - you've come to far with your project not to succeed

Jfrahm

Still operational here. No trackdays but lots of full throttle blasts. The kit is making great power. I would like to condense down to one 968 with the supercharger but I am buried in cars and projects right now. My 1992, I could pull the motor and swap in some forged rods and migrate the blower over to it this winter I guess. I would like to fix up the blue 94 the supercharger is currently on but I think it is too beat up for me to undertake the project. I love the Iris Blue color but do not care for the idea of repairing it's many cosmetic issues.

Santa could bring me a really nice Iris Blue cabrio with low miles on a 2R rod motor for Christmas, that'd be a great present. I'd want to swap in a linen interior but I can't ask for too much... Plus I can't say I've been good.

-Joel.

Lemming

Car survived the 90 minute enduro, first in class!!! Biggest issue with the car was brake proportioning, not the SC!!!! Power oversteer is fun when used properly. More after the weekend when I have time.

Damian in NJ

YEAH!

Mark944na86

Hats off! (To both you and Carl...)

edz968s

Excellent, good job
No issues with belt wear, etc?

Mark944na86

Yes, you can run the car without the balance belt, some racers even delete the balance shafts entirely to gain a few extra hp, but it will have a lot more vibration than an engine with the balance shafts rotating in correct counterbalance to the rotating mass of the engine.

If the belt is fitted incorrectly and the balance shafts are not properly positioned with respect to the engine timing (and each other), the vibration can actually be made much worse than running without. This sounds like what may have happened in your case.

Who set the balance belts at the last belt change? Although it's pretty easy if you know what to look for, it's an easy thing to get wrong if you are unfamiliar with the 944/968 series cars.

Not to cast aspersions, but If I were you I would consider getting the engine checked over by a third party to be 100% certain of correct set-up and alignment before proceeding with trying to debug your s/c related problems. You wouldn't want your timing belt to go the same way as the balance belt...

FraMac

Good man Tim - well done - look forward to hearing more.

rgs944

Great job, Everyone wants to hear more, any video?

Lemming

Exhausted, what a great weekend! I managed 1st in class in the morning sprint that was cut short due to a crash. Second sprint was going well and I was 1st in class till the belt started slipping and saw that my boost was down so I called it a day. To be honest it was my fault, I looked at the belt before the race and thought that it felt a bit loose compared to what I had been running. Unfortunately there was not much time between sprints and I was busy running a fund raiser for the Cancer Center. I was going to put a new belt on before the sprint but did not have time. I think that if I had just tightened it I would not have had a problem.

I've got some good video but that will have to wait, too tired at the moment.

Carl Fausett

Well done, Tim. We may find that racers should change in a new belt every month or so... we'll see.
Are you running the Stage 1 or Stage 2 pulley? I'm coming to the conclusion that racers should run the Stage 1 (larger) pulley on their kits because of the high sustained loads on the belt. The larger pulley provides more tractive force onto the belt.

Lemming

Stage 1 pulley.

edz968s

Stage 2 pulley with me, so hence maybe the accelerated belt wear. After the track day event the belt was worn completely across the centre. Possible to knurl all of the centre?
Have now got the S1 pulley being fitted, but have the issues of changing all the belts.
With the S1 pulley, presumably this will also address the fueling problems on track
So the conclusion is Stage 2 for road and Stage 1 for race/track use with the more prolonged full throttle usage

Dubai944

Belt wear and belt slip seem to be a couple of the main limitations to developing the 944/968 kits for more than general road use. I use another kit but irrespective of which kit you are talking about I am convinced the basic mechanics of a small crank pulley dictating very small supercharger pulleys has to be overcome.

I have been racing my supercharged 968 powered 944 in the UAE GT series for the last year and although the car has done well I have had continual issues with belt slip, inconsistent boost delivery etc. I went through the development of different belt arrangments, more pulley wrap, belt sprays and cross grooving the 6 rib pulleys in an attempt to keep the boost delivery consistent over 1 hour races with limited success.

I have just had made this custom 7 inch, 8 rib crank pulley and 8 rib pulley set which allows me to run a 3.5 inch pulley on the charger instead of a 2.55 for similar charger speed.

To fit this requires deleting of the power steering pump which has been converted to electric to get rid of the need for a belt, deletion of the timing belt covers to clear the new crank pulley and a few other mods, but I am hopeful I will have solved the belt slip issue forever. This pulley was designed to sandwich between the balance belt crank pulley and the S2 harmonic balancer which I wanted to retain due to vibration issues I previously had without it. The ultimate goal is to run a 3 inch charger pulley with this setup which spins the charger at its maximum design speed at redline and use one of Carl's boost limiting valves which I have to control boost level.

All this is experimental and home grown, but it seems to me the supercharger kits are now gaining a lot of acceptance as a legitimate alternative to turbocharging for track racing and the kit makers could probably come up with more elegant drive setups which properly solve belt problems and cater to those wanting more to develop for more power.

Lemming

That's a cool solution, I hope it works.

Like I said, I believe that the belt slip issue was really my fault. I put a brand new belt on before the weekend and failed to tighten it up after day one (2.25 hrs track time). I then went out Sunday and tried to put another 1.5 hrs on that belt, shame on me I'm thinking one belt per race weekend will easily do the trick, time will tell. At around $20 a piece, that's ok with me. If I want to be cheap, I can reuse them for DE weekends when I'm instructing or test and tuning.