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Aluminum flywheel for Autocross

Old 07-16-03, 11:54 AM
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hahahaha
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Old 07-16-03, 11:56 AM
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theres nothing there.
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Old 07-16-03, 06:23 PM
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There was. This is the first time this has ever happened to a post I typed. No one was answering anyways so I will just buy an aluminum flywheel and come to my own conclusion about Mazdatrix's claim that the engine will have more "torque coming out of a curve" using the stock heavy flywheel. Bah, I doubt it.
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Old 07-17-03, 09:12 AM
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Definitely worth it. Probably the best "power adder", IMO. Makes much better usage of the available powerband.
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Old 07-17-03, 02:41 PM
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Yea good buy
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Old 07-17-03, 05:25 PM
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Great buy, but if you're autocrossing BE CAREFUL and don't go too light. You still need to keep some weight to help you get off the corners so the revs don't drop too far. Even the 4 rotor that raced at last years Lemans didn't break out the super lightweight flywheel (they made it heavier @ 15 lbs so that they can keep the revs up and get out of a corner earlier...it's still lighter than stock so you'll definately gain some acceleration). But yes, the flywheel is a great thing
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Old 07-17-03, 07:41 PM
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Wow, some replies. Thanks guys. About revs dropping and having power coming out of a curve with a flywheel of moderate weight, how? This is what I don't understand. To "have power coming out of a curve" all rotating mass in the drivetrain must be accelerated to add any power to the tires if trying to accelerate a car moving at a constant speed (when rounding a corner for example). So I am wondering how having any more rotating mass than necessary to start the car off from a stop with the clutch would be helpful. Unless there is an upshift involved I can't see any benefit to a heavier flywheel.

Oh well. My car will be the guinea pig. I am trying to shed all weight possible without losing the interior or having the car get too loud for street driving. I basically see the project as an airplane from an execution standpoint.

Thanks guys! Race car tech rules.
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Old 07-18-03, 09:34 AM
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Originally posted by redrotorR1
Definitely worth it. Probably the best "power adder", IMO. Makes much better usage of the available powerband.
I pretty much agree with this. I've been using a light flywheel for a couple of years with good results.
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Old 07-20-03, 07:57 AM
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What I'm saying is that the slightly heavier flywheel will help you keep the revs up a bit so you can get off of a corner quicker than with a superlight flywheel. The lighter the flywheel the quicker you can rev/accelerate, but don't forget the lighter the flywheel...the quicker you drop revs (you'll notice) thus making it harder to come off a corner. If I can find the article on the 4 rotor again I'll get you the link. But I do stand by what I said earlier...don't go TOO light .
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Old 07-20-03, 12:30 PM
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I think I see what you are saying. Letting off the gas in order to brake for a curve and needing the flywheel to spin down more slowly in that situation than if it was super light.

Nothing a little left-foot braking couldn't fix.
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Old 07-20-03, 02:53 PM
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True left foot braking could help with this "problem", but I don't know the techniques that everyone else uses so I just state it as general info. Some people don't have a problem with this at all (people who are very fond of heel and toe shifting/braking), but some people aren't quite that advanced at driving and would definately try to give the lightweight components a bad name because they couldn't utilize it fully but don't know it's their fault and not the products (not everyone knows that driving is a science).

Hopefully that'll help you out and anyone else who's thinking about this right now or in the future (here's to hoping that they found the "search" button ).
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Old 07-20-03, 03:39 PM
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Thanks for the info KiyoKix. I have always wondered about the loss of torque issue in turns and you helped clear it up.

If I ever get this rig finished, I think I will try to drive autocross with left foot braking right off the bat. It will seem awkward for a few events but maybe all that forklift time I have will help out (left foot braking is common with Hysters - the brake is the clutch that allows you to rev the engine and move the forks faster). Not having to get my foot off the brake and back on the gas might shave some time if I could get proficient. There was a thread in this board about this topic . . . some guys said that left foot braking saved them a couple seconds on the course. That is quite a bit of time to save just by changing driving technique.
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Old 07-21-03, 09:39 AM
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Originally posted by KiyoKix
What I'm saying is that the slightly heavier flywheel will help you keep the revs up a bit so you can get off of a corner quicker than with a superlight flywheel. The lighter the flywheel the quicker you can rev/accelerate, but don't forget the lighter the flywheel...the quicker you drop revs (you'll notice) thus making it harder to come off a corner. If I can find the article on the 4 rotor again I'll get you the link. But I do stand by what I said earlier...don't go TOO light .
I disagree. The heavier flywheel does not keep revs up any better than the lighter flywheel when there's a load on the drivetrain. Revs drop faster when the load is disengaged (i.e. clutch in); but the only time that happens is when you shift. How much time do you lose by that fraction of a second that the revs drop 100-200rpm more? Not very much at all. And what you make up for with the increased acceleration more than cuts the difference.

I don't doubt that the IMSA or the LeMans teams had good reasons to go with a slightly heavier flywheel. But, the factors in choosing the flywheel were probably not centered on rpm drop. F1/Champ cars have extremely light drivetrain assemblies. Clutch AND flywheel that weigh 10-12 lbs TOTAL.

That said, too light of a flywheel makes the car very hard to drive on the street. I've driven a heavily modified SM car with an extremely light flywheel. It takes a bit of practice .... and I wouldn't want to drive that in traffic.
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Old 08-01-03, 01:26 PM
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Light Flywheel

Originally posted by 88IntegraLS
There was. This is the first time this has ever happened to a post I typed. No one was answering anyways so I will just buy an aluminum flywheel and come to my own conclusion about Mazdatrix's claim that the engine will have more "torque coming out of a curve" using the stock heavy flywheel. Bah, I doubt it.
One of the best things I have done for my car. I heard both sides about going lite. Yes do it, no it will slow you down. Once you try one you will never go back. My car is a mainly for autox. I run in SM2 and the flywheel helps you rev quicker, thus get into boost quicker.

Good luck.

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Old 08-07-03, 05:39 PM
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Originally posted by redrotorR1
I disagree. The heavier flywheel does not keep revs up any better than the lighter flywheel when there's a load on the drivetrain. Revs drop faster when the load is disengaged (i.e. clutch in); but the only time that happens is when you shift. How much time do you lose by that fraction of a second that the revs drop 100-200rpm more? Not very much at all. And what you make up for with the increased acceleration more than cuts the difference.
Yup!!!
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