Lightened Flywheel
12-28-2004, 06:13 PM
#1
Burning Brakes
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Lightened Flywheel
I pulled the flywheel off my spare motor recently and noticed that it had been lightened. Question: 0.45" of the motor side of the flywheel has been machined off and thus two of the three screw-in sensor set screws on the rim of the flywheel are no longer there as they are normally installed in the part that has been machined off. Are they not used for anything ? The sensor screw on the rim closest to the clutch side of the FW is still there. Just want to make sure this flywheel is good to use, as I've never run this engine myself.
BTW, for those of you interested, the specs on the flywheel are (compared to a stock one I also have):
Original weight = 15.2 lbs
Lightened Weight = 11.0 lbs
Savings = 4.2 lb
Original thickness = 1.27"
Lightened thickness = 0.82"
Metal removed from engine side FW rim = 0.45"
BTW, for those of you interested, the specs on the flywheel are (compared to a stock one I also have):
Original weight = 15.2 lbs
Lightened Weight = 11.0 lbs
Savings = 4.2 lb
Original thickness = 1.27"
Lightened thickness = 0.82"
Metal removed from engine side FW rim = 0.45"
12-28-2004, 08:59 PM
#2
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The set screws that have been removed are for the diagnostic TDC sensor. The TDC sensor is not used and is not plugged into anything. You'll be fine without those set screws.
12-30-2004, 03:16 PM
#7
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Fidanza offers a lightened flywheel for N/A. You could have yours machined down like these have been. The advantage would be that you could keep some weight in the rotational mass for ease of driving. Make sure you do your homework on a lightened flywheel before you purchase and install one-it will change the way the car drives-and if you don't like it you will be looking at serious labor to replace.
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12-31-2004, 03:28 AM
#8
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HY M8NC: Tell me about it! Just did the mods that you all speak of.
Spec stage 2 + lightened clutch and a NEW Fidanza alum flywheel (Didn't actually weight it from the renlister I bought it from, but he stated it was a little over 6lbs)
I hate having to rev match on downshifts...and have to rev her at least 2,000 at lights or it stalls. This mod will make a master clutch maniplulator out of you! But dam I can feel the huge difference!
Spec stage 2 + lightened clutch and a NEW Fidanza alum flywheel (Didn't actually weight it from the renlister I bought it from, but he stated it was a little over 6lbs)
I hate having to rev match on downshifts...and have to rev her at least 2,000 at lights or it stalls. This mod will make a master clutch maniplulator out of you! But dam I can feel the huge difference!
12-31-2004, 04:43 AM
#9
Race Director
rev to 2K to be able to take off is why I didnt get the Fidanza. I wonder if that has something to do with the clutch as well... mine is only 2.5 max lbs than yours and I can drive off the line very close to what I did on a stock setup.
12-31-2004, 11:25 AM
#10
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I've heard that the lightened flywheel doesn't make a Dyno difference. Do you guys have #'s? Exotic Motorwerks in Phoenix do a ton of PCA racer work on 944s as well as 928s, 911s etc and know the cars cold... They said they bought a few of them installed them, didn't see a difference then the rules changed and they had to remove them. Dan also mentioned that there were no points given of subtracted for the (null difference) and inferred from that they make no difference either way (plus they dyno'd and saw no impact).
12-31-2004, 12:00 PM
#11
Race Director
First of all, if you have to rev to 2k at a light to keep the engine running, the flywheel is not the problem. Something else is wrong.
It takes a little more effort to drive with a low mass flywheel, but it's not a big deal. My wife is not a car person, yet drove our G20, first with a lightened OEM flywheel and later with an aluminum flywheel on a turbo engine, for two years. No troubles. The aluminum flywheel with the turbo was nice because it revved that much quicker to get the turbo on boost that much quicker.
A low mass flywheel will not show a hp gain on a brake dyno. It will on an inertial dyno. A low mass flywheel does not add any power. But, because of the lower mass the car will accelerate quicker giving the illusion of more hp. Quicker acceleration is quicker acceleration. I personally love low mass flywheels.
It takes a little more effort to drive with a low mass flywheel, but it's not a big deal. My wife is not a car person, yet drove our G20, first with a lightened OEM flywheel and later with an aluminum flywheel on a turbo engine, for two years. No troubles. The aluminum flywheel with the turbo was nice because it revved that much quicker to get the turbo on boost that much quicker.
A low mass flywheel will not show a hp gain on a brake dyno. It will on an inertial dyno. A low mass flywheel does not add any power. But, because of the lower mass the car will accelerate quicker giving the illusion of more hp. Quicker acceleration is quicker acceleration. I personally love low mass flywheels.
12-31-2004, 03:49 PM
#12
Nordschleife Master
Five or six pounds off the wheel makes a noticable difference in vehicle acceleration? I can see it making the engine rev faster when in neutral, but I find it hard to believe it makes the car accelerate measurably faster. Has anyone ever done back-to-back aceleration tests to verify this?
12-31-2004, 04:54 PM
#13
Race Director
Originally Posted by Peckster
Five or six pounds off the wheel makes a noticable difference in vehicle acceleration? I can see it making the engine rev faster when in neutral, but I find it hard to believe it makes the car accelerate measurably faster. Has anyone ever done back-to-back aceleration tests to verify this?
12-31-2004, 04:58 PM
#14
Race Director
Isnt the stock fly 15lbs? That would make closer to 9lbs off... I did the fly and underdrive pulleys and AC delete at the same time. It revs a LOT faster, but it would be the combination of all.
