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lighter flywheel: [email protected] vs [email protected]?

Old 10-30-03, 12:15 PM
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lighter flywheel: [email protected] vs [email protected]?

I'm considering buying aluminium flywheel or lightening the stock one. But I've heard the car loses some torque in the lower rpm band with this modification. Gains should be more power in higher range and better throttle response. This is the theory, but I'd like to know how is that in reality. Please, post your comment about this issue, prefferably from your own experience.

The car I'm trying to build will be used also as a drift car, so I want to make as much usable power as possible. It will run jspec twins, so the spool-up time should be good (and consequently throttle response), but they are a bit lower on torque than stock ones. What do you think, should I go with lightened flywheel or not?

Thanx for answers!
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Old 10-30-03, 01:50 PM
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Here's a quote from a fellow forum member about lightweight flywheels:

Yes, less load on the engine therefore less drag during the rev. Disadvantage is poor acceleration out of the hole for a launch, ie Drag racing. You need the inertia of the heavy flywheel because we lack torque, and since you don't produce much boost from a standing start, maybe 4 or 5 psi, the inertia from the flywheel spinning at high rpm helps to keep the engine from bogging out of the hole. The benefit on a road course is the flywheel is light and since you are slowing and accelerating rapidly the engine can recover the power faster if it doesn't have to work as hard to spin the flywheel to get the power to the ground.
Having posted that, I'm using a lightweight flywheel. The only negative difference from stock that I've noticed is that you have to slip the clutch a little more on "getting the car going from a stop". The positive difference from stock is that there is more available power in the lower gears since the rpms climb so fast.

I enjoy the lightweight flywheel, even on the street.
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Old 10-30-03, 03:37 PM
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Thanks for answering Mahjik. Actually, that's what I was thinking and it seems the logical explanation to me... The only disadvantage should be only present, when operating with clutch. That's what it seems logical. But today my mechanic (has a few year of experince in racing and building race cars) told me that, for example, at [email protected] there will probably be less torque than with stock flywheel. That's what sursprised me. At least this is how I understood him. He said the most gain should be apparent in higher rpm band (more power), and that all turbocharged cars have heavy flywheels. But for example wrc cars, do have very light ones... Anyway, this is why I decided to clear this issue and try to lookup some more comments and see what people that have them installed say... Thanks again.
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Old 10-30-03, 04:55 PM
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In a older grass motorsports mag i have they compared to 5.0 mustangs. One with a stock flywheel and one with a lightened. The lightened one had a car length on the stock in the 1/4
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Old 10-30-03, 06:43 PM
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You might also check Max's site:

http://www.maxcooper.com/rx7/parts_i...heel/index.htm

He has some great info there. I hope some of this helps out.
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Old 10-31-03, 07:02 AM
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A flywheel does not create torque.. it only has inertia. Torque comes from the engine. So your output numbers, if you put the car on a dyno, should be higher everywhere.
The trade off, like everyone else has said will be during engagement, when the extra mass helps drivability.
Good luck
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Old 10-31-03, 07:03 AM
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Originally posted by soru81
But today my mechanic (has a few year of experince in racing and building race cars) told me that, for example, at [email protected] there will probably be less torque than with stock flywheel.
That may be true, but the light flywheel will still let the engine accelerate more quickly than a heavier one, so the time spent at that RPM is less as the engine accelerates.

Flywheels do NOT add nor subtract torque. Flywheels create momentum for the engine. Once you spin a heavier flywheel up, the engine will take longer to slow back down. This means if you drag launch at 6000 rpm for instance the heavy flywheel will keep more momentum (RPM) in the engine as the clutch engages and the car hooks up. On the downside (for anything other than drag racing) you now have to expend engine power spinning that heavy sucker all the time. You also get less engine braking with a heavier flywheel because the engine will not decel as quickly when you lift the throttle.

Lighter flywheel the way to go.
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Old 10-31-03, 07:17 AM
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A lightweight flywheel will dramatically improve your throttle response. The car will feel a lot faster, and you will get into the meat of the power band a lot quicker as well. I think it's one of the best go-faster mods I've done to my car. The downside, if you really call it that, is that you do need to slip the clutch a bit more.
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