Charlie944

I am leaning towards getting a clutch kit from Markus Baszak from Blaszak Precision Motorsports in Canada, and I wanted to get some feedback before I took the plunge. This is for the Callaway 944 and Markus recommended using his Stage II pressure plate (30% increase clamping) and his stage III kevlar disc in the 225mm NA sizing so I would not have to change out my bellhousing, clutch fork, flywheel, etc. He said that particular kit is rated for 425hp. I will be using a Fidanza as well. Any feedback would be greatly appreciated.

special tool

I would not use kevlar on any 2 valve turbocharged Porsche if you are shooting for big torque.

SoloRacer

I have the same set up in my car and have had no problems with it. (dynoed 300 rwhp/280 lb-ft torque - Vitesse Stage III) Best of all though is Markus himself. He has been great to deal with. I know that ST has expressed his concerns about the Kevlar clutch but so far I have no reason to believe that mine is slipping or will slip. If mine did slip I would probably go with the Kennedy pressure plate. Hobart Kennedy is another man that I respect and who is easy to deal with. Just my $0.02

Peckster

If Markus says good for 425 hp you can believe him.

theedge

I knew he sold clutch discs, didnt know he had pressure plates. Thats nifty.

Marcus is a great guy to deal with.

Charlie944

Thank you guys for the feedback! That is reassuring. I was orginally going to go with a KEP and clutchnet Carbon disc but then I started talking with Markus, and he suggested I build up my NA setup. And I liked the idea of not having to change over a bunch of parts along with keeping costs down a bit more.
Soloracer: do you have the 225mm NA size clutch or the larger 240mm turbo setup? Markus did mention that he has installed the smaller clutches in turbo cars to reduce rotational mass and decrease spool up time.
Originally the Callaway 944 cars had 284hp @6000 with 10psi and 230 ft/lbs torque @ 4000. I am cofident I have a bit more due to the MAP sensor on the TEC2, 15psi, and a free flow exhaust, but I have not dyoned the car yet due to my slipping overpowered clutch.

I would lilke to get a different turbo in the future to replace the IHI RHB6, so I want a clutch that will hold up to future mods.

special tool

Charlie - please ask Markus if he has any dynoed ANYTHING with over 375 torque at the wheels before you make your decision (with kevlar clutch). ESPECIALLY since you are going to play with turbochargers.
Also - check with old man Kennedy about using kevlar on a high torque engine.

SoloRacer

Charlie: I have the turbo kit not the N/A one. As for kevlar I have a friend with an RX7 Turbo making 500 hp and he was running a kevlar disc. When we pulled the engine out last fall for a freshening the clutch still looked like new. I'm curious myself to see what Hobart says about them so I might call him in the next week or so. For now I am happy with what I got and even happier with the service from Markus.

One thing that Markus did mention (as did the vendor of the clutch for my RX7 friend) is that the Kevlar clutch needs to be broken in first. If you burn them early on they won't last long. I know that ST has claimed to have problems with a Kevlar clutch slipping and he said it was very difficult to tell until he got a different set up and saw the difference. I don't know how that clutch was broken in though and I don't know how the set up he used compares to the one that Markus sells.

Charlie944

Markus's Kevelar disc is the same money as the clutchnet.com Carbon disc so should I go with that instead to play it safe? I will ask Markus about the torque rating with the Kevlar discs. Thank you both for your help. I will report back what I hear from Markus.

Charlie944

Markus said that he has the Stage 3 Kevlar setup on his Supercharged 944S2 that puts down >350hp/375ftlbs torque from 1500rpm to redline and with zero problems. I will email Clutchnet on their ratings for their Kevlar and Carbon dics to get some more info. Markus also stated that:
NA Stage 2 will hold 392hp
NA Stage 3 will hold 425hp
951 Stage 2 will hold 450hp
951 Stage 3 will hold 512hp
This is with his 2275lb pressure plate and Kevlar disc.

Charlie944

I did a some more research and found an article in Turbo Magazine on clutches: Kevlar, for instance, is known for its insulating properties. As a friction material, this is a problem. Kevlar doesn't recover from overheating very fast because it doesn't transfer the heat off of the surface. The result is a material that can cook the mating surfaces (flywheel and pressure plate) and has a lower-than-stock coefficient of friction to boot. Yes, it lasts a long time if treated right, but it's not ideal.

Contradictory to the above I found this: http://www.southbendclutch.com/kevlar.html

I will have to find the friction coefficients of carbon type clutches and the Kevlar.
The formula for torque capacity is:

T = P x F x N x R
where:
T = torque in ft-lbs
P = pounds of clamping force
F = coefficient of friction
N = number of surfaces (generally 2)
R = radius of gyration (mean radius of the friction surface) in feet

special tool

The newest thing is bronze/ceramic (little smoother than copper ceramic, but still very high c/f) - why don't you give this a whirl.

Charlie944

Thanks ST for the recommendation!
To whom or what vendor would I look for to get this disc?

pk951

http://www.clutchnet.com/make/prodDesc.html#6bEZ

special tool

Yes - I use something similar to the 6 puc solid hub on that site.
But mine is copper/ceramic.

Jimbo1111 has found a disk tthat is BRONZE/CERAMIC. Thee bronze material is supposed to ease the engagement just slightly, yet retain the awesome friction (and heat management!!!!!!!!!!!) of the copper/ceramic.
If I was buying one now for a 951, I would probably get the one that Jimbo111 got.
I don't know where the hell he got it, however.
Send him a pm - hopefully he'll be in a good mood.....