Light weight flywheel = less torque?

[wilch]

Just a quick question guys,

I'm getting a Daikin heavy duty clutch installed, and have the option to get a lightweight flywheel. I've heard that I will loose torque if I do. Is this true? Will I notice?

[2rismo]

Get the factory one skimmed - you'll be happy.

Adrian

[wilch]

Will that be enough?

I was also wanting more response. Quick rev'ing etc.

[mjfawke]

Just a quick question guys,

I'm getting a Daikin heavy duty clutch installed, and have the option to get a lightweight flywheel. I've heard that I will loose torque if I do. Is this true? Will I notice?

Yes - you will notice the difference, it will be a little harder to get going smoothly. More revs, a bit more clutch slipping etc.

As for 'lose torque' - what a load of total BS. A flywheel is an energy storage device, for lack of a better term, and if you are putting energy into your flywheel, it is not going to your wheels. Think of it in terms of how much effort you have to put into swinging a bowling ball around your head vs. swinging a ping-pong ball. This is why F1 are now using 4.5" clutches...

[wilch]

That makes sense.

So basically the revs will rise and die down quicker (when reving in neutral for example), kind of like a motorbike?

Now I'm assuming that this will also equate to faster acceleration. Am I right in assuming this?

[mjfawke]

Yes to both.

[wilch]

Cheers.

Thanks heaps for the info!!!

[MonstaS4]

It will rev up and down sharper like a bike engine. A lighter flywheel has less inertia.

I'm not sure about the torque though. Torque is equal to the force applied times the radius through which it acts. So if you have less weight/force at the extreme of the radius, and the radius remains the same you would have less torque. Correct?

[mjfawke]

The torque is unaffected, but acceleration is reduced (acceleration = force / mass). Reducing the diameter of the flywheel but keeping the same weight increases acceleration - the flywheel is accelerating at different rates (centre accelerates slowly, outer edge accelerates quickly). You'll have to read up on "moment of rotating inertia".

So 300Nm of torque in = 300Nm of torque out, but a larger/heavier flywheel accelerates more slowly.

[someonestolecc]

Doesn't it decrease engine braking effectiveness? (as it is easier to spin)

[Bass Junky]

MY experience with a light flywheel is that it increases acceleration. Idles a bit crappy with the standard comp, revs quicker.

Only downside is that the "stored energy" isn't there when changing gears, so sometimes if you aren't fast enough with the change (in anger of course) you get a lull in acceleration for a moment before the thing gets back on the boil.

But the better acceleration outweights any minor ad points.

Rev210 picked up 0.4 accross the quarter.

[dangerous_daveo]

One thing I have heard from people with bigger turbos is a light weight wheel causes more lag. One of my mates actually went to a heavier than stock flywheel to try and reduce the lag a little. But that could have been because he had a wrx with a dog box and aluminium puck clutch, so Id guess the next weakest item breaks then being the flywheel (ps that last bit is a joke)

[shaolin]

Yes - you will notice the difference, it will be a little harder to get going smoothly.  More revs, a bit more clutch slipping etc.

As for 'lose torque' - what a load of total BS.  A flywheel is an energy storage device, for lack of a better term,  and if you are putting energy into your flywheel, it is not going to your wheels.  Think of it in terms of how much effort you have to put into swinging a bowling ball around your head vs. swinging a ping-pong ball.  This is why F1 are now using 4.5" clutches...

So you would not notice anything on the hills???

I had been told you would notice a difference...

[nizmokid]

the age old flywheel question!!!!!

[mjfawke]

So you would not notice anything on the hills???

I had been told you would notice a difference...

Better acceleration up the hills, but less engine braking down the hills.

[Anquetil]

I put in a lightened flywheel as well as a Exeedy HD clutch.

It's hard to explain, but it just didn't get up as much in the low-mid range. It didn't have as much 'push you back in your seat' feeling and I found it actually took longer to rev out to red line?

Afterwards I wish I hadn't had it done, on the track though it may be beneficial.

[mjfawke]

I put in a lightened flywheel as well as a Exeedy HD clutch.

 

It's hard to explain, but it just didn't get up as much in the low-mid range. It didn't have as much 'push you back in your seat' feeling and I found it actually took longer to rev out to red line?

 

Afterwards I wish I hadn't had it done, on the track though it may be beneficial.

Sounds like your new clutch/flywheel is heavier than your old setup, or you have a problem with your engine.

[FATGTS-R]

My mate has a 140rwkw na R31 and installed a lightweight flywheel.

As mentioned by others the first and most obvious difference you will notice is that you need more revs to get the car off from a standstill.

He was stalling it for the first day as he wasnt used to feeding it so much revs. It idled a little worse so he just increased idle speed a tad.

You really need to change your driving style with one, as he also noticed he had to change gears a lot quicker, even just driving around sedately.

But his personal opinion is that the pros outweigh the cons.

[Brackez]

The phenomena often referred to in discussions about lightening engine/driveline components about climbing hills depends largely on what you are doing with engine rpm/throttle position while approaching a hill. An engine with a lighter flywheel will, if a constant throttle position is maintained, lose rpm faster than a standard one. HOWEVER- the lightened flywheel (with less inertia) has less resistance to an increase in rpm, so if approaching the same hill you, say, go back a gear and feed in more throttle it will provide better ACCELERATION up said hill than a standard, heavy flywheel (assuming the engine has sufficient HORSEPOWER to accelerate the car up the hill in the first place ).

[Beer Baron]

for me (having driven a few cars with lightened flys) the biggest drawback is the greater rev drop between gearchanges. that is the main negative in my eyes. if you can live with that, go for it.