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Benino
Joined: 30 Jan 2003 Posts: 505 Location: Vista, CA (San Diego County)
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Posted: Tue Dec 04, 2007 5:28 pm Post subject: 924 n/a flywheel cross section & lightening |
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I made a scale diagram of the cross section of the 924 n/a flywheel.
I'm planning to have mine lightened. Here is the cross section. The light gray areas are the parts I'm thinking of having removed. I think that whole area and all the way to the end is just for weight purposes, not for strength. part of the friction surface to the inside of that, is already that thin. I think the area closer to the center (which is thinner) would need more strength since it has to be able to handle the centrifugal force of the mass of the rest of the flywheel.
_________________ 1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA |
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!tom
Joined: 28 Aug 2006 Posts: 1930 Location: Victoria, BC Canada
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Posted: Wed Dec 05, 2007 6:29 am Post subject: |
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There's also the heat capacity of the flywheel to consider. The majority of the mass that you're planning on removing is adjacent to the friction surface of the flywheel. Removing this will cause the temperature of the flywheel to increase over an un-modified flywheel when operating the clutch, due to the reduced heat capacity of the flywheel.
If your driving style is clutch friendly, this would probably not be an issue. However, I wouldn't be surprised if a lighter flywheel would lend itself to more clutch slipping than a conventional flywheel, and consequently that much higher temperatures.
Just something to consider. . . _________________ 78 924 NA
5-lug |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1076 Location: The Netherlands
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Posted: Wed Dec 05, 2007 5:21 pm Post subject: |
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I had my flywheel lightened. The took 1,5 KG of the back (engine side). This safe and won't effect the strength.
Ofcourse you can get more of it (by putting holes in it). But you will loose strength. _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11723 Location: PacNW
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Posted: Thu Dec 06, 2007 2:57 am Post subject: |
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So you removed material from the same area as in the pic above? _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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AppleBit
Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN
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Martijnus
Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands
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Posted: Tue Mar 11, 2008 1:45 am Post subject: |
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I've heard some stories from people who took too much off... a shattered flywheel isn't fun... so keep limits in mind
interesting thread however... I'm not interested in weight loss in this case but you never know how I think about it in a few yrs _________________ "Rule: Turbo's make torque, and torque makes fun." (C. Bell)
924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment |
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AppleBit
Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN
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AppleBit
Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN
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Benino
Joined: 30 Jan 2003 Posts: 505 Location: Vista, CA (San Diego County)
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Posted: Tue Mar 11, 2008 1:59 am Post subject: |
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Yup. I had mine lightened. Its back in the car and working fine. It looked pretty much exactly like the picture AppleBit posted. I'm pretty sure I took some pictures of it before I installed it, but I have on my home PC.
I did pretty much exactly what I have in my cross section diagram. _________________ 1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA |
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Nobbi
Joined: 24 Aug 2006 Posts: 1379 Location: Germany
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Posted: Tue Mar 11, 2008 2:00 am Post subject: |
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Whats the positive effect of a light-flighwheel ? _________________ NA 924 - april/1977- 4-speed-audi gearbox.
500.000 km with fun.....and new toy:Porsche 944 S2 Cabriolet.Other car Daimler c-class cabby,brandnew..Plus : DEUTZ 4005 tractor Built 1969 |
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AppleBit
Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN
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Martijnus
Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands
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Posted: Tue Mar 11, 2008 2:10 am Post subject: |
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AppleBit wrote: | Nobbi wrote: | Whats the positive effect of a light-flighwheel ? |
+ Faster revving engine
+ Easier on the engine
- Loss of torque (minimal)
- Has to be done right or BOOM! |
what do you mean by "easier on the engine" ... the flywheel smoothes out the peaks in an engine iirc, especially when idling. _________________ "Rule: Turbo's make torque, and torque makes fun." (C. Bell)
924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment |
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AppleBit
Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN
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Posted: Tue Mar 11, 2008 2:14 am Post subject: |
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Martijnus wrote: | AppleBit wrote: | Nobbi wrote: | Whats the positive effect of a light-flighwheel ? |
+ Faster revving engine
+ Easier on the engine
- Loss of torque (minimal)
- Has to be done right or BOOM! |
what do you mean by "easier on the engine" ... the flywheel smoothes out the peaks in an engine iirc, especially when idling. |
If you had a 25 lb weight or a 5 lb weight, and you were swinging it around with your arm, what would be easier?
Another idea with the less weight is it can then consume less fuel... Now this all is more like a variable along with other things.... _________________ Classic British Sports Car Restoration v6 + v8 Engine Conversion Swaps
Porsche 924 Wide Body LS1 Corvette 500 Horsepower Engine |
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Benino
Joined: 30 Jan 2003 Posts: 505 Location: Vista, CA (San Diego County)
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Posted: Tue Mar 11, 2008 2:35 am Post subject: |
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Nobbi wrote: | Whats the positive effect of a light-flighwheel ? |
any decrease in weight of the rotating drivetrain parts is going to mean less power lost between the engine and the wheels. _________________ 1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA |
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Rich H
Joined: 10 Jun 2007 Posts: 2665 Location: Preston, Lancs, UK
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Posted: Tue Mar 11, 2008 2:41 am Post subject: |
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Did you guys balance them afterwards? _________________ 1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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