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questions about a flywheel

 
Old 08-29-2001, 11:08 PM
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'86turbo
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how would shaving down a flywheel affect the power stroke of an engine? i have heard that the inertia of the flywheel is used to help move the crank and a lighter flywheel would affect engine driveability at idle. one more thing along the same line can a engine run without a flywheel attached?
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Old 08-30-2001, 10:20 PM
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IPC
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In a nut shell, the flywheel is a big weight that keeps the crank shaft turning in between power strokes. If you lighten the flywheel it can rev quicker because it is having to move less weight. The down side is with the light flywheel the engine is more likely to stall. (no weight to get it to the next power stroke) In a race car you don't spend much time at idle so it is not a problem and you want the engine to rev as quick as possible. In a street car do you want to deal with to possibility of it stalling when you come to a stop or even just slow down. The flywheel also balances the engine so it runs smoother. The engine would run without it just very rough if you could start it, no ring gear for the starter. Hope this helps.
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Old 09-02-2001, 01:04 PM
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Howard
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I have a light flywheel on my racecar and IPC is right, it's quicker revving, but the idle has to be set around 1100rpm to prevent stalling. The downside is when you "blip" the throttle to downshift , it falls off so quickly I actually have to hold the throttle at the proper rpm to shift. I have a buddy who installed a light flywheel on a 3.6 , it won't idle, he had to go back to the dual mass wheel.
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Old 09-05-2001, 11:02 AM
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Steve, 914 guy
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I have a 7# flywheel on my 4 cyl, I sure can upshift a lot faster now, while not banging gears.
It idles a little rougher, but it's a racecar.
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Old 09-06-2001, 04:21 AM
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Steve Weiner-Rennsport Systems
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Originally posted by Howard:
<STRONG>I have a light flywheel on my racecar and IPC is right, it's quicker revving, but the idle has to be set around 1100rpm to prevent stalling. The downside is when you "blip" the throttle to downshift , it falls off so quickly I actually have to hold the throttle at the proper rpm to shift. I have a buddy who installed a light flywheel on a 3.6 , it won't idle, he had to go back to the dual mass wheel.</STRONG>
Hi Howard:

I've used light (6 lb) aluminum flywheels on carbureted and MFI'ed 911's since 1976 with no stalling issues at all. I might suggest that you have a look at your ignition advance settings at 1000 RPM and make sure that you have about 8-10 deg advance at idle, this will prevent the stalling that you have.

You should tell your buddy with his 3.6 that the stalling with the lightweight RS flywheels on those can be cured in software if its a 95 or earlier OBDI engine. He does NOT have to use the dual-mass nor add weight back on to cure that.

The '96 and later OBDII 3.6's can handle the RS setup without any changes, just fine,....
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