Thread: Flywheels in dragsters.

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Just curious.

A question came up on another forum related to dragsters and the flywheels they use.

Some say dragsters use a very heavy flywheel while others say they typically use a lighter weight one.

Which way is it, and what is the "science" behind the choice?

Thanks!

Which ever it is, It has to be a approved part.
And you'll get a number with it to show to the tech at the trac.
I belive the weight comes in with how much you want to spend on the part.$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$.


~ Vegas ~

Not that I have any experience on the matter, but my logic would tell me that I would use a heavy flywheel with slicks and a light flywheel with street tires. The heavy flywheel could be used to store energy before the launch, but you would need slicks to put all of that energyto the ground because it will dissipate quickly. It will also make you less likely to stall the car at the line and may also help with consistency for bracket racing. A car with a heavy flywheel isn't going to peg the rev limiter as quickly if you lose traction, giving you a little more time to react with the throttle. The heavy flywheel helps tame peaks in your powerband which might otherwise cause you to spin the tires.
As for light flywheels, they give you better throttle response. If you do lose traction, you can stop the tires spinning more quickly with a light flywheel because it has less inertia. A light flywheel makes shifts faster because it takes less time for the engine to slow to the rpm of the next gear.

I remember years ago that the Junior Stocker cars with little 265's and 283's in a heavy car ran 50 lb. flywheels to help launch 'em.

I talked to Kip Martin recently and asked him what he used in his 64 1/2 Mustang with a 289, he said 35 lbs. with a 4-speed. He sits the car on the back bumper at launch every time. It's exciting to watch.

A comparison would be, with a round track race car you would want a light flywheel for quick response off of the corner where the rpm's fall off. With a drag car you would need a heavy flywheel that would store energy before the launch at high rpm's.

Back in the old blown gas dragster days we used aluminum flywheels and direct drive. We didn't have quite enough hp to pull the way the Top fuel guys did so thus the alum fw. This is why we ran 8.0's and 180+ lots of top end. With the advent of the slipper clutch we tried the alum fw but there was too much heat and many found the hard way what happens when a clutch lets go at 8000+. We did...boom 2 piece race car.
Eventually the Crowerglide came along. It was alumin at first but it didn't hold up. We used a steel fw about 10# or so. They are much smaller than stock dia. but with 3 discs and floater they probably got up to 30 pounds or better. I remember them being a handfull to pack a complete one around.

I remember some of the old gassers using 265 and 283 that used 50-60 fw. they would wind them up to 8500 and dump the clutch. The motor stayed there while everything else caught up....if it stayed together. I saw one 2 piece 55 chev that was a tremedous blast. parts flew everywhere.

bentwings

I concur with Techinspector 1. Way back when, (and I'm plenty old enough to remember "way back when" - like the 50's) there were plenty of classes for small displacement engine/heavy cars. These guys successfully used some very heavy flywheels. I recall one stock bodied Willys coupe that ran a little 170 c.i. Mopar slant six and was plenty competitive in his class.

The pracctice was to build up as high rpm as one could manage while sitting on the line, in effect storing up bunches of horsepower in the spinning flywheel, then dropping the clutch. If the clutch held together, the car departed abruptly.

The downside was that once that stored-up horsepower petered out, that flywheel became just a big heavy chunk of steel for a little dinky engine to lug along.

But! If things worked together just right, the heavy-flywheel guy could put humiliating holeshot on the competition that was enough to get him to the lights first. Usually just barely, but what the heck. That's the whole idea, ain't it?