Hey I just picked up a 2001 M3, Leguna Seca Blue, and I love it. the previous owner put a UUC stage II clutch and 8.5lb flywheel in the car. I know all about the gear rattle noise, and that doesn't bother me, but I have never driven any other e46 M3s and was wondering if anyone could tell me how much of a difference there is between the stock dual mass flywheel and the UUC 8.5lb flywheel? Thanks!...by the war I love my car, I'm so glad I upgraded from a chipped 2000 S4.

There is a pretty big difference. You will be faster, more so in lower gears. the higher gear you are in, the less of an effect you will feel from the LTW flywheel.

The motor revs almost twice as fast with the LTW Flywheel. I think the RWHP freed up from a flywheel is like:

2.3(i think)HP per lb saved ... but its different in each gear

I like to divide the total hp increase by which gear I am in to get a rough estimate of how the effect of the flywheel is less in each gear.

the UUC system saves about 15 lbs (the stock flywheel is 25lbs, but the M5 clutch used in the UUC system is heaver so its equal to stock clutch 10lb flywheel).

so 15*2.3 = 31.5RWHP gain in 1st gear call it 30rwhp

31.5 / 3rd gear = is like 10RWHP

in 6th its like 5RWHP..

these are not real numbers it would really be a formula where the gear ratios where used.

maybe 2.3*(lbs saved)*gear ratios... but that would mean 1st gear is 30*4.23. hmm maybe divide by the final drive ratio...3.62

1st gear 30*4.23/3.62 = 35RWHP Gain in 1st Gear
2nd gear 30*2.53/3.62 = 21RWHP in 2nd
3rd gear 30*1.67/3.62 = 14RWHP
4th gear 30*1.23/3.62 = 10RWHP
5th gear 30*1/3.62 = 8RWHP
6th gear 30*.83/3.62 = 7RWHP

hmm, I wonder how close these numbers are... of course they are based on a 2.3RWHP gain per lb.


BTW, if you liked your chipped S2000... get headers and then chip your M3:D

hmm, I wonder how close these numbers are... of course they are based on a 2.3RWHP gain per lb.

Don't know if you've seen this... we do all the math for you!

http://www.uucmotorwerks.com/flywheel/how_a_lightweight_flywheel_works.htm

The first three gears seems very substantial. Is this legal in ASP autox class where it would really prove it's weight in gold?

The first three gears seems very substantial. Is this legal in ASP autox class where it would really prove it's weight in gold?


probably not... lightweight flywheels are usually not allowed, or have weight restrictions.

but there are some classes that allow almost anything so...

So how do you think it would affect the 0-60 time? 1/4 mile? Just curious...

it would shave about 2 tenths off of your 1/4 mile time and about a tenth off of your 0-60. its so much more effective in 1st and 2nd.

Question for UUC and the board. I understand the concept of less rotating mass and faster reving. I have a little difficulty with the equivalent of 3-400 pounds less weight. Has anyone done a before/after dyno pull?

Question for UUC and the board. I understand the concept of less rotating mass and faster reving. I have a little difficulty with the equivalent of 3-400 pounds less weight. Has anyone done a before/after dyno pull?

You will not see results in a dyno pull. You will see results in acceleration.

The gain comes from a "virtual" mass reduction... if you literally took weight out of your car, would you expect an improvement on the dyno? Of course not... but you would expect better performance.

Please read the link I posted earlier:

http://www.uucmotorwerks.com/flywheel/how_a_lightweight_flywheel_works.htm

- Rob