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hey guys, about to change my clutch in preparation for turbo. going with the xtreme heavy duty clutch and was thinking of getting a lighter flywheel while im at it. has anyone had experience with the xtreme chromoly flywheel?

http://www.xtremeclutch.com.au/page.asp ... oductid=15

Chrome moly light-weight, CNC machined from chrome molysteel
Heat treated wear resistant surface
Appropriate weight designed to reduce inertia and improve engine response

its about $365. is it worthwhile going to the lighter flywheel for a 8psi td04 turbo.

I've got an Xtreme aluminium lightweight in my car (non turbo). They're quiet noisy, I don't know if I'd bother for a daily drive but for a track car yes.
The cars very drivable and I've never had any problems with staling it due to having less mass. Not sure about the chromoly ones though.

I would certainly read a bit more into lightweight flywheels with Turbos before handing over the dough.

I could be wrong but i believe losing mass would in fact create less load on the engine therefore taking longer to create boost.
Causing "lag".

Again, i am no expert but i would research a bit more into it.

That sounds counter-intuitive. To me it is no different to going to a lighter wheel, or losing 20kg weight from the body - you are not affecting anything to do with airflow in the engine/exhaust. Full throttle is full throttle.

Id have to disagree with mark, the car will take more rpms perhaps to come on boost, but less weight means that those rpms will come sooner, hence having no effect on perceived or actual spool time, but the car will accelerate faster.

Dann

Ummmm.... I am talking about engine load. Not vehicle weight.
Engine load is what spools a turbo.
Hence no boost in neutral.

Weight on the crank, ie-Flywheel, is directly associated with engine load.

If you remove the weight I believe spool time will be increased.
To what extent I do not know.

Any experts care to comment??

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As above, load is decreased, hence total rpm needed to spool (boost threshold) will be greater, but the car accelerates faster now, so total time to spool is similar.

Dann

Thanks Dann.
Makes sense.
Do you think it is exactly even?
Like the lighter you go with the flywheel it will keep up with the loss of spool , acceleration wise??

For an example, in a drag race scenario??

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Id say the lightest everything possible always wins...?

But who cares, im building a car with a turbo AND a supercharger!

Dann

Flying miata used to recommend light flywheels for supercharged and name cars. STD for Turbo, they have since changed this and recommend lightened for all induction types.

Don't know any deaper detail myself.

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FM USED to recommend a heavier clutch for turbocharged applications which never made sense to me given that a turbo's power is based on rpms - a heavier clutch will take longer to rev than a lighter one. FM now recommend a lighter clutch for turbocharged applications.

Here's an extract from their site:

http://flyinmiata.com/index.php?deptid=4531&parentid=0&stocknumber=08-26500%20%2010.30
"We offer them in 13.5 lbs, often referred to as a "street" setup, and 10.3 lbs for a little more responsiveness. The heavier unit will be a little quieter on overrun (lightweight flywheels can cause the transmission to make noise on closed-throttle deceleration) and a bit easier to drive. The stock flywheel is around 20 lbs. The heavier weight is also well suited to supercharged cars to avoid idle droop, while the lighter model is for those who are looking for the sportiest experience."

Spooling takes time - time required to accelerate the turbine and time to pressurise the intake system. With an infinitely heavy flywheel the rpm won't change at all, but it will still take time to get the system 'boosted'. Now with 'no' flywheel in the system, in the time it takes to generate boost the rpm will rise significantly, but the overall acceleration of the system should be quicker, because you are seeing a bigger change in rpm over the same time duration.

Or that's my logic anyway.