flywheel? why not!

CJFusco · CJFusco's Garage

I was talking to a 911 owner today (who owned a 944 previously) and he told me that as long as I'm gonna be changing my clutch I should also install an aluminum flywheel. He said that it is one of the easiest ways to increase a 944's performance, and the difference will be night and day...

...sooooo, I am pricing flywheels, and the cheapest I can find is about $250. Does anyone know where I can find one cheaper? Has anyone done this?

SoCal Driver · SoCal Driver's Garage

There is no "performance" gain with an aluminum flywheel. Might catch the rev's a bit quicker with the clutch in but once the clutch couples up there is no difference.

drew1 · 08-05-2003, 03:04 AM

I think Alum a lighter flywheel helps in both speeding up & slowing down. The only place I think it could hurt is at top end starting up a hill where you have less energy stored up in the flywheel, so the hill slows you down quicker, or the slightly bigger rpm drop when getting up through the gears.

An option you may want to think about is cutting the iron lip where the pressure plate bolts up & replcing it with an aluminum ring.

drew1

TCMdocs944 · 08-05-2003, 05:14 AM

I know that rotational weight is supposed to be much more important than "curb" weight with any vehical.
Anyone have one of dem dar super duper aluminum fly's?? What is the difference in feel?

Harpman · 06:07 AM

To accelerate your car from 1000 RPM to 6000 RPM requires your flywheel to do the same thing. A lighter flywheel is easier to accelerate, allowing more of the engine's torque to go to your wheels.

As you approach top RPM in any gear, you are no longer accelerating the flywheel so the benefit then dissappears, so for instance your top speed will not increase any more than if you took the extra few pounds out of your car by removing your carpets.

Some racing Stock Cars have a very light flywheel to help with max acceleration out of each turn, but they practically stall when standing still unless the driver keeps the rpms up, because there is not enough stored rotational enery in between piston strokes.

So you may need to set your idle a few hundred RPM higher.

Bottom line: you get some acceleration improvement (which is great of course), but no noticeable higher top speed.

Also as Drew1 said: "the slightly bigger rpm drop when changing through the gears" this could be annoying. I haven't done this flywheel change myself, so get some more opinions here from folks who did before you go for it.

TCMdocs944 · 08-05-2003, 06:11 AM

Hey, sounds like just the upgrade for me since my car runs about 200rpms too fast at idle anyway

Thanks for the sublime description Harpman.

924Sman · 08-05-2003, 06:33 AM

Another consideration to make....Lightened flywheels are not allowed in most stock class racing. So if racing is your mindset this may be of help. Sman

drew1 · 08-05-2003, 06:21 PM

"Anyone try one of them super duper alumuninum flywheels?"

I have run light flywheels in several cars. Only Porsche was a 914, where it made a big difference in aceleration in the gears & deceleration when backing off. Also it seemed to help in gear engaging in downshifts.

On a Chevelle street car & drag racer years ago, it hurt compared to stock flywheel off the line.

In a 55 Chev dirt tracker, a great improvement. You stay in one gear all the time & acel & backing off was no comparison.

As Harpman says you might need to idle it up, especially if you have a lopey lope cam. I had an old Z28 off road cam in the 283 in my dirt tracker & it wouldn't idle at less than 1500-1600. That lick it had makes me smile. Another thing is with a light flywheel you have to give it a little more gas letting out the clutch & taking off from a dead stop.

I lightened the flywheel by about 4 or 5 lbs for the motor I'm going through for my wife's 924t. If I get on this computer & get to work on it maybe I can give an evaluation.

drew1

krankenwagen · 08-06-2003, 04:58 PM

I installed a turbo clutch with the Fidanza aluminum flywheel into my '86 N/A and I love it! I ended up having to take the N/A ring gear and have the ID machined out to fit on the turbo pressure plate, and have 9 new counterbored holes drilled into it. The turbo ring gear wouldn't work because of the different # of teeth. The computer got really confused with the turbo ring gear installed, and would lean out the mixture at around 3000 RPM. It was so bad that it would backfire through the intake when you tried to rev it up. After converting it(correctly), the engine revs. up and down a lot quicker, and the car seems to accelerate a bit better. Double clutching on a downshift is definitely a lot more fun. At first, the lightened setup took a little getting used to when taking off on steep hills, you have to rev the engine a little higher to get moving. I have the S2 40% locking diff. transaxle installed, which is geared higher, so that just made it harder to get used to. Now that I have been driving it this way for a couple of months, I don't even notice it, but I cringe every time I get into my girlfriends '86 N/A. Her car is bone stock with an open differential and it feels lame in comparison. I am extremely glad I changed it over to the lightened flywheel and turbo clutch and would never even think about going back. The modified ring gear, turbo pressure plate, turbo clutch disk, turbo throwout bearing, turbo throwout fork, and the Fidanza aluminum flywheel were all that was needed for the conversion(minus the bolts and rear main seal).