Is anyone using an underdrive pulley in CSP? I know this was the hot setup on a ST Miatas. I am running a 2003 motor in a '90 NA.

 

If you plan on not having to rebuilt the motor as often, I'd go with one of 949 Racing's harmonic balancers. Its not a quite a light as the underdrive pulleys, but it will do the job and reduce the stress in the oil pump and crank.

 

I had a custom made with integrated tec3 wheel built on.. Now installing PS and bought a 90.00 ebay dual and am having it machined down right now. It you don't need an integrated wheel.. 90.00 is cheap.

 

not sure what CSP is but i know an un-dampined pulley is a fast way to mess up an oil pump

 

CSP is an scca autox class. The rules dictate you run a motor with stock (sort of) internals. Bolt on parts are legal such as headers, intakes etc. Some people are making serious horsepower but nothing as strong as a forced induction motor.

 

Well I mean there are Blower kits and turbo kits that only make like 160 wheel so yeah, some of them actually do make more power than some boosted cars. If the car only does CSP its going to take it a while to work up enough time on the engine for the light weight pulley to kill it. Put it in perspective there's CPS cars that have been reving to 8k and have lightweight pullies for multiple seasons without blowing up. Course those are towed to the event.

 

I remember Bill Schenker posting he was running the miata roadster superdamp and was pushing 77-7800 SAFELY (99 motor with 01 head and weight-matched internals). And supposedly 7900k is the "line of doom" for 01+ motors (vvt) with stock internals. Apparently the 94-97 motors can do 8k regularly w/o exploding? Can anyone confirm/deny? -Just reposting what I've seen csp pr0's say about their setup. But then again I'm still running my 1.6 so wth do I know...

 

Not to knock on autocrossers, but the most abused autocross cars might see 3 or 4 total hours of runtime in a year, or about what Rover will do in a single enduro/sprint weekend. Even with the trickest harmonic damper out there, you cannot spin a motor with factory rods to 7600+rpm and expect it to be reliable in the long run. Autocrossers get away with stuff like 8000rpm on a stock bottom end and running aluminum crank pulleys because the motors just don't get used that much - if you tried the same stuff in a car that just saw HPDE duty, you'd blow stuff up on a regular basis.

 

Totally agree, track weekend with 8k revs would be a short one, I just mentioned those specific limits since the OP stated this would be under autocross conditions.

 

No arguments here. There was about a months time where I was considering building a 100 hour NA engine for SSM because it would last multiple seasons if I trailered. You cant quite run grenade engines like they do in drag racing, but depending on your class and budget you can get close.

 

would have to agree, dont see an engine lasting very long if you regularly run it at 8k

 

Forget about putting an underdrive pulley on you car... You won't see much of an improvement in performance if anything... but, your engine will see a great deal of increase in wear and tear.

 

Sorry, but you cannot run a '99 motor with the '01 head legally in CSP. You have to use the entire engine, in other words, it has to be an '01+ block and head or a '99 block and head.

 

Yep that should have read, 99 miata with 01 motor. Whiskey is a bitch.

 

Bill runs the ATI on his 99. Not sure what Kubo runs but the 949/TSE pulley is a great option. less weight and stronger than stock and won't screw **** up.

FWIW I never had an issue with en UD pulley with STS power levels and a stock rev limit, but Sav is right...better safe than sorry.