lighten the S2 flywheel
11-12-2005, 12:25 PM
#16
Three Wheelin'
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I lightened (had lightened) the flywheel on my S2 and added a spec clutch. I can feel the difference, although I would not do this mod on a car that you plan on driving on the street too much.
I would do it without thinking twice and enjoy the ride when you're done.
11-12-2005, 12:30 PM
#17
Rennlist Member
Good to hear.
I'm just embarassed that a stock Grand Prix GTP can just kill my 944 off the line, and was looking how to get quicker accelleration without breaking the bank account. This sounds like it has some potential.
But there has to be some downsides here someplace. Anyone? It is harder on the engine?
I'm just embarassed that a stock Grand Prix GTP can just kill my 944 off the line, and was looking how to get quicker accelleration without breaking the bank account. This sounds like it has some potential.
But there has to be some downsides here someplace. Anyone? It is harder on the engine?
11-12-2005, 12:48 PM
#18
Three Wheelin'
Technically the flywheel weight is calculated so that it dampens the forces from the pistons firing so if you lighten the flywheel you should also be lightening your rotating assembly and rebalancing it all. That is pretty much the book answer but in reality most people I know of that have lightened their flywheels have no problems with it except that they have to relearn how to drive and be careful not to over rev until they get used to the feel since it spins up so much quicker.
11-12-2005, 02:52 PM
#21
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Originally Posted by eohrnberger
You are saying that the amount of clutch pedal throw to engage the clutch is shorter? Or that when the clutch does engage, it grabs and is jerkier?
One would think that if it's either, it's just a re-training of the left foot to be smooth again.
One would think that if it's either, it's just a re-training of the left foot to be smooth again.
11-12-2005, 02:53 PM
#22
Drifting
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Originally Posted by eohrnberger
Good to hear.
I'm just embarassed that a stock Grand Prix GTP can just kill my 944 off the line, and was looking how to get quicker accelleration without breaking the bank account. This sounds like it has some potential.
But there has to be some downsides here someplace. Anyone? It is harder on the engine?
I'm just embarassed that a stock Grand Prix GTP can just kill my 944 off the line, and was looking how to get quicker accelleration without breaking the bank account. This sounds like it has some potential.
But there has to be some downsides here someplace. Anyone? It is harder on the engine?
11-12-2005, 02:55 PM
#23
Rennlist Member
Originally Posted by URIN 2ND
Still have no idea why people say this. This is on my daily driver and I've done it to many cars in the past as well. I have never noticed one adverse effect...only a VERY substantial increase in acceleration and a willingness to rev. Technically, with less rotating mass (and less inertia) the RPMs should drop quicker in between shifts, but this has never been a problem. Some other people claim it's "harder to drive on hilly terrain". AFAIC, this is not true at all.
I would do it without thinking twice and enjoy the ride when you're done.
I would do it without thinking twice and enjoy the ride when you're done.
11-13-2005, 03:10 PM
#25
Rennlist Member
I spoke to a retired PhD mechanical engineer from the automotive industry about this specific topic. His reasoning is from 20 years of working with the big 3 balancing their engines and engine designs (boy! does he have some engineering horror stories!).
The conclusions that he came to was that lightening the flywheel would create greater wear on the main crank bearing. His reasoning is as follows: The flywheel is smoothing out the explosive shock of combustion that travels down the connecting rod and is transferred to the crank. Since the flywheel needs to be accelerated with this shock, greater flywheel weight reduces or smoothes this shock. Take away some weight form the flywheel, and greater acceleration is possible, but that combustion shock will wear harder on the cranks main bearings.
Seems to make sense to me. Worst case, an engine would last like 200K miles instead of 250K miles, right? And then, it would only be the crank main bearings, right?
Anyone have any non-theoretical experience to share? What's your take of this reasoning?
The conclusions that he came to was that lightening the flywheel would create greater wear on the main crank bearing. His reasoning is as follows: The flywheel is smoothing out the explosive shock of combustion that travels down the connecting rod and is transferred to the crank. Since the flywheel needs to be accelerated with this shock, greater flywheel weight reduces or smoothes this shock. Take away some weight form the flywheel, and greater acceleration is possible, but that combustion shock will wear harder on the cranks main bearings.
Seems to make sense to me. Worst case, an engine would last like 200K miles instead of 250K miles, right? And then, it would only be the crank main bearings, right?
Anyone have any non-theoretical experience to share? What's your take of this reasoning?
