Lightweight Fly really not good for drag racing?
05-10-07, 05:13 AM
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Lightweight Fly really not good for drag racing?
I was really excited about picking up a lightweight fly, because I read everywhere that it made the engine rev more quickly (I come from sport bikes, I love that quick rev) and that it'll help when at an autox. However, then I read that it really hurts you when you're at the dragstrip, that made me pause a bit. As it stands now, I've been drag racing more than I have autoxing, though I hope that may change later. In any case, I've searched for a good 2 hours or so and can't really draw much a conclusion. Could the people with lightweight flywheels who drag chime in? Did the lightweight fly really hinder your 1/4 or 1/8 mile times?
05-10-07, 05:30 AM
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from what i understand about lightweight flywheels is that they have less inertia due to the reduced weight. this is good for auto-x and the like, because you're constantly changing throttle input. however, with drag racing you want that greater inertia because it gets the car moving and keeps in moving.
05-10-07, 06:04 AM
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A light flywheel only makes it hard to launch, especially when combined with an aggresive clutch.
There is allot less margin between engaging too hard too fast and burning out, and bogging down off the line.
After the car has left the line the light flywheel becomes and advantage.
There is allot less margin between engaging too hard too fast and burning out, and bogging down off the line.
After the car has left the line the light flywheel becomes and advantage.
05-10-07, 06:44 AM
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+^^
A light flywheel only makes it hard to launch, especially when combined with an aggresive clutch.
There is allot less margin between engaging too hard too fast and burning out, and bogging down off the line.
After the car has left the line the light flywheel becomes and advantage.
There is allot less margin between engaging too hard too fast and burning out, and bogging down off the line.
After the car has left the line the light flywheel becomes and advantage.
only hard to start off the line.
but can be just as good if you rev it right before droping the clutch.
05-10-07, 07:46 AM
#6
Lightweight flywheels are an absolute advantage when you want acceleration. Street, track, autox, drag, it's a performance advantage.
The trick is that you need to be good at launching with it or your 60' times will get worse.
The downside for street driving is that the lighter the flywheel the less easily it will engage.
Dave
The trick is that you need to be good at launching with it or your 60' times will get worse.
The downside for street driving is that the lighter the flywheel the less easily it will engage.
Dave
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05-10-07, 09:15 AM
#8
Once you let off the throttle and coast, yes the stored energy of a spinning flywheel will sustain the rolling of the car longer. This makes a heavier flywheel more streetable. But in drag racing you are accelerating all the way from the start to finish and this doesn't apply.
Dave
05-10-07, 10:39 AM
#9
I love quoting the following findings whenever this discussion comes up to help fully illustrate just how much difference a light flywheel makes hp-wise!From back in '03 (https://www.rx7club.com/showthread.p...7&page=2&pp=15)
That is not correct. The engine must spend energy to rotate the flywheel. A lighter flywheel or one with more of the mass towards the center will require less energy to rotate. The effect is more hp to the wheels. Max Cooper did some research and calculated that you will get around 50 more hp to the wheels in 1st gear, around 16 in 2nd gear, and neglible in the higher gears. It does not "feel" like more hp, it allows more horsepower to the wheels -- less drivelines loss.
http://www.maxcooper.com/rx7/parts_i...heel/index.htm
http://www.maxcooper.com/rx7/parts_i...heel/index.htm
~Ramy
05-10-07, 10:41 AM
#10
Most people stick with the stock flywheel or actually heavier if your using forced induction. As you shift on the dragstrip with a lightweight flywheel you can fall out of boost. Lupe;Viking War Hammer (Eric) can be a reference to this situation.
05-10-07, 02:17 PM
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Right, but I'm still on the stock twins, so I wouldn't think falling out of boost would be much of a problem for me. I just basically didn't want to not be able to launch at all. From what I've been reading, I'll have to drop it at around 5k now instead. The problem with that on other cars would be that they have much more powering, making launching at that RPM very hard. I'm hoping since I'll only have bolt-ons, that dropping that high won't be as hard for me since I won't be having to deal with as much power. I just hope the ACT S/S clutch can handle dropping it that high.
05-10-07, 06:35 PM
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ha! i knew i wasn't completely off.
05-11-07, 10:13 AM
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Unless you have a large turbo, you don't really have to worry about the lighter flywheel being that big of a deal.
Option 1. If you are going for all drag, use a stock flywheel.
Option 2. If you want a little of both, use a lightened flywheel, just not superlight.
The idea is that you can potentially fall out of boost (RPM) easier on launch and in-between shifts with a lighter flywheel due to the fact you don't have as much rotational mass keeping the RPM up due to inertia of the heavier part. IF you have a larger turbo this could pose a concern because the problem is magnified. If your on stock twins, go for option 2, you will be happier.
Option 1. If you are going for all drag, use a stock flywheel.
Option 2. If you want a little of both, use a lightened flywheel, just not superlight.
The idea is that you can potentially fall out of boost (RPM) easier on launch and in-between shifts with a lighter flywheel due to the fact you don't have as much rotational mass keeping the RPM up due to inertia of the heavier part. IF you have a larger turbo this could pose a concern because the problem is magnified. If your on stock twins, go for option 2, you will be happier.
05-12-07, 10:10 PM
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I had a light one and went back to stock.. nicer to drive etc etc. better for drag racing in my exp... plus does anyone know of any proven dyno runs to show more power??? yes it revs faster but i liked the stock mucho..
Greg
Greg
05-13-07, 02:19 PM
#19
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