JDWalton

Hey guys, I know theres alot of personal opinion sorrounding the two, so if we can stay away from that influence in here too much, and just lay actual facts it would help me greatly.

So I am looking at getting a Spec 2+ clutch soon (maybe even a 3+) and am wondering about these flywheels. Aside from what people usualy try to bash aluminum with, what are your thoughts.

For example, people always say aluminum is weaker, but I havent seen the horor stories about people running them on our cars and breaking them either.


If I can here feedback from some people actualy running these setups it would be even better.


This is what I am looking at getting, also mods are in sig:
http://www.brenspeed.com/sf463h.html
and
http://www.brenspeed.com/sf46a.html or http://www.brenspeed.com/sf46s.html

hammeron

steel has more mass than aluminum, simply
imagine the implications, when using one
or the other.

one example to get things started:
more mass means it will spin down slower.

JDWalton

So I take it you like steel better because your going with the instantaneous increase you gain between shifts, assuming your motor has spun down more then the the shift itself would lower it, will give you more of a increase then a loss in rotating mass that will benifit your entire rpm band while on the gas?

hammeron

i did go with steel, because i wanted a stock
like feel. it feels good, but the aluminum may have
felt good too

i know it's a tough choice

JDWalton

Yeah, I see alot of people on the fence about the aluminum. I may go for it just to see for myself. I have heard the point you made before from a few, and it makes sense, I just dont think with such a small pool of potential energy it has enough energy to effect a bigger overall change across the range of a 1/4 or more. Either one though I doubt has a large change against eachother

hammeron

well if you do go aluminum JD, let me
know how you like it and if you can
feel a difference in the way the car
revs

Lifter583

I just put in a Spec Stage 2 in my GT. I called spec and discussed the flywheel issue. They said the steel is much better for daily drivers and road trips. The extended heating of driving longer and in summer etc will cause warping of the aluminum eventually. Steel is much more long term heat resistant. I went with steel, feels great, just came out of breakin.

BruceH

.........

Norm Peterson

No.

I think what hammer is getting at is that if you keep the revs above where the next gear wants them to be that the larger rotating mass will give you a bigger 'surge'. That does tend to momentarily help you in a drag race, as the extra rotational momentum very briefly behaves like extra torque as the clutch engages again.

The flip side, of course, is that greater flywheel mass revs up more slowly (all else equal). You need enough flywheel mass to make starting from rest easy enough for you without bogging it or having to slip it wildly, but not so much that it overly hurts the engine's ability to rev up.


I'd consider a light flywheel for serious autocrossing or road racing, and possibly for a lightweight daily-driver. Not for a heavy car or one that would be expected to pull anything other than a very light trailer.


Norm

JDWalton

Yeah, thats the other downfall I have heard to aluminum, though no one seems to quantify "Eventually." I mean if you get 60,000 out of it instead of 120,000 I don't really care, I put 6,000 on it in just over a year, and that was with 3,000 when I was forced to use it for work.


As for you norm, good catch, what you said is exactly what I intended to say, I just goofed it up.


This isn't a daily driver and its not a race car. Its a car I take out when I want to have some fun. The most it would normally go without a cool down time would be like 30 to 40 miles (distance from my house to the Berlin Turnpike if any of you are familiar,) then sit for a while, then make a 1 mile trip, sit for a while, 1 mile trip, sit, repeat a few times in a night, then drive home. Not to say it will never be driven farther, but thats about the worst of it.