I was curious about actual horsepower gains from a lightened flywheel, 2.7hp/lb (horsepower per pound) being the common throw around answer in various circles. I found this article which applies actual physics (imagine!) and breaks it all down. I'm too tired to summarize, if you got this far take it one step further and click HERE then scroll down for the discussion on lightened flywheels.

Reading the whole article is worth it, but here's the summary. Essentially, lightening the flywheel DOES NOT increase horsepower, but it DOES allow your car to get to its horsepower faster, which would lead to faster acceleration, so it may have the same affect for most people. Every post I've read on this site raves about lightened flywheels, I would assume because of the fact of increased acceleration.

Summary from article:

"Finally, a flywheel will not show much of a gain in horsepower on a dyno because it doesn't increase fuel or air and can't increase horsepower. [B]Remember, you're not actually improving your car's power, just how quickly it can get to that power.[/B] An inertial dyno will show gains by the engine reaching a predetermined rpm sooner with a lightened flywheel."

 

Yeah, most people are mistaken about what flywheels actually do. It makes the crankshaft easier to rotate, thus it takes less work (hp) to turn.

 

Yep. That backs up what I said in the earlier thread.

 

how much does it cost to buy one of these performance flywheels + parts/labour

 

My lightweight came with my Centerforce clutch.... I would imagine that would be cheaper cuz most who buy a flywheel also replace the clutch and vice versa. labor is usually around $65-80 an hour in most shops.

 

I've been told that, although you may gain on your revs and all, you lose torque. It makes sense. Once you get that mass rotating, it's harder to stop it. As opposed to the light flywheel. It's just as easy to slow it down as it is to speed it up.

Does that make sense?

 

You don't lose torque, that's a common misconception. I run a 7.5lb flywheel and haven't lost any torque.

 

yeah 7.0lb here and it DEFINITELY hasnt lost torque. You still have a lot of rotating mass besides the flywheel to contend with such as the crank and the entire connecting assembly. Its like lightweight connecting rods, you lighten the moving mass but you retain performance and rpm. IF they didnt improve performance then they wouldnt be on the market right? :-P

 

The flywheel will store initial energy for the launch. As a result when the clutch initally grabs there is more force. Once the clutch is fully engaged the flywheel becomes dead weight that the engine has to rotate. The less the engine has to rotate the faster it can respond to the throttle.

 

Do those of you that have the lightened flywheels notice much? Do they really quicken your revs that much?