bigsnorlax

Are these a yes or no for boosted motors? There are some aftermarket ones that are crazy light compared to the stock one. I get the whole "less rotational mass and you can rev it up faster deal" but in between shifts will a lighter flywheel cause an engine to slow down so dramatically that RPMS will plummet and loose boost?

It seems fairly advantageous (is that a word? haha) to me that i think id like to opt for one. The faster we get into a given (but higher) RPM range is less time out of boost any ways right? I know this is probably just the tip of the iceberg as far as theory or the actual physics are concerned but i would just like to know how you guys feel about them on your street cars.

4cylfiend

iTrader: (1)

Im with the rotational mass theory.. I am going to run a stock LS flywheel because of the heavier weight. I can see the lighter flywheel benefiting a N/A car alot more than on a F/I car. Im sure there are alot of different views on this but my personal opinion is to use a stockish weight one on a F/I car. Last year I ran a act 12lb flywheel but that is no where near some of the 7lb ones you can buy. Also the heavier rotational mass will help load the turbo when launching and also when brake boosting.

Jaker

I cannot argue with someone that has an 11 sec Civic, but I fail to understand the theory behind what you've said.

h22-eg-hatch

iTrader: (1)

Lightened flywheel is better

I run a 9lb on my boosted h22 eg
Runs n feels better then the 25+lb stock one. For sure.

In my opinion u should get something lighter then stock but not too light.

95civich2b

I wouldn't go lighter then 12lb on a boosted application just going to cause more wheel spin not that we don't already have enough..

CleanLikeJdm

So something that adds no real HP will make your tires spin easier?

Is it the light FW, or not being able to control quicker revs?

wolve

bogus!

when brake boosting the engine does not see any difference between a 30 or 7lbs flywheel as the rpms stay stationary

the whole if i shift i fall out of boost because rpms drop too fast. that just means you can't drive and shift slow! if you shift fast enough your rpms will have not reached the rpms you fall back to. that is not taking into considiration that you should never fully lift or preferably full throttle shift on a FI setup if you want to stay in boost.

only reason you would opt for a heavier flywheel is for smoothness, street traction and a relaxing caracter.

GettingOut

The lighter, the better. For ANY setup. The ONLY time you should go with a heavier flywheel is if you can't spin your tires a bit from a dig if you're running slicks and do a redline launch. If you try that, and your car bogs, you need more inertia to transfer torque to the wheels when you dump the clutch.

Lighter. Better.

Also consider, most of us have already replaced the tiny stock rods with massive forged I-beam rods, so we've added considerable mass to the rotating assembly already. I run a 9-lb flywheel with I-beam rods and CP pistons and there's no way in hell the RPMs fall too fast between shifts. In fact I'd love if they fell much faster because it'd be less stress on my synchro hubs.