Change in Flywheel weight vs HP/TQ
TECH Fanatic
Joined: Jun 2002
Posts: 1,979
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From: Upstate NY
Loooong answer:
The engine would not produce any more/less HP/TQ at a steady rpm with a rotating inertia change (heavier/lighter flywheel). There would be a difference during engine acceleration which is happening most of the time when racing, well except maybe for the Daytona oval.
The increase/decrease in torque or hp to the flywheel or, more importantly to the wheels, depends on the total rotating inertia (wieght) and the acceleration RATE. The quicker the engine accelerates from one rpm to another the bigger the difference in hp/tq getting to the flywheel or tires.
In other words, rotating inertia makes more difference in the lower gears when accelerating than in the higher gears.
If you drop 10 lbs. from your flywheel you might notice it in 1st and 2nd gear, but if you went from 16 inch to 18 inch wheels and wider tires, the extra inertia of the tires wold probably negate the lighter flywheel's effect.
Would I spend money for a lighter flywheel if I were not racing? Nope.
Jon
Thread Starter
10 Second Club
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Joined: Nov 2003
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From: Ft. Lauderdale, FL
Short answer: probably not a lot on the street that you would feel. Starting from a stop might be a little nore trouble with a lighter flywheel, especially with a lumpy cam.
Loooong answer:
The engine would not produce any more/less HP/TQ at a steady rpm with a rotating inertia change (heavier/lighter flywheel). There would be a difference during engine acceleration which is happening most of the time when racing, well except maybe for the Daytona oval.
The increase/decrease in torque or hp to the flywheel or, more importantly to the wheels, depends on the total rotating inertia (wieght) and the acceleration RATE. The quicker the engine accelerates from one rpm to another the bigger the difference in hp/tq getting to the flywheel or tires.
In other words, rotating inertia makes more difference in the lower gears when accelerating than in the higher gears.
If you drop 10 lbs. from your flywheel you might notice it in 1st and 2nd gear, but if you went from 16 inch to 18 inch wheels and wider tires, the extra inertia of the tires wold probably negate the lighter flywheel's effect.
Would I spend money for a lighter flywheel if I were not racing? Nope.
Jon
Loooong answer:
The engine would not produce any more/less HP/TQ at a steady rpm with a rotating inertia change (heavier/lighter flywheel). There would be a difference during engine acceleration which is happening most of the time when racing, well except maybe for the Daytona oval.
The increase/decrease in torque or hp to the flywheel or, more importantly to the wheels, depends on the total rotating inertia (wieght) and the acceleration RATE. The quicker the engine accelerates from one rpm to another the bigger the difference in hp/tq getting to the flywheel or tires.
In other words, rotating inertia makes more difference in the lower gears when accelerating than in the higher gears.
If you drop 10 lbs. from your flywheel you might notice it in 1st and 2nd gear, but if you went from 16 inch to 18 inch wheels and wider tires, the extra inertia of the tires wold probably negate the lighter flywheel's effect.
Would I spend money for a lighter flywheel if I were not racing? Nope.
Jon
Thanks for the great response. I am definitely interested in the race application. My set-up is for racing with an occasional Saturday night street spin.
In a application with slipper clutch, I believe any extra weight at the flywheel will be negative to ET. I was curious if their is a direct relationship for every 10lbs reduce related to the amount of increase TQ. You bring up a good point that the quicker the engine is accelerating the greater the benefit of reducing the rotation weigh.
Thanks again,
Bob
Teching In
Joined: Feb 2010
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The higher gear you are in, the more benefit it will make. It will make a lot more power in 4th than it will in 1st. I wish I could find the article, but they did back to back dynoes, and found staggering results, results that you and I would be buying aluminum flywheels like they were magic power adders. Truly spectacular results, I want to say like 80whp in 4th gear on a Corvette.
