if you lightend your flywheel and dynoed your car would the hp be different from the wheels then from the crank.......if so how much

 

wait let me reword that............does a lightned flywheel make hp at the wheels. I know it doesnt at the crank


Modified by nitekidsef9 at 6:09 PM 6/3/2004

 

on fwd hondas is usually 14-16% loss

 

The engine doesn't make any more/ less power due to a flywheel, but a lighter flywheel means the engine has less inertia, and this will translate into faster acceleration and more "power" (depending on what gear you're in, etc).

Since most dynos are inertial dynos (they see how fast a drum gets angularly accelerated), the flywheel will show up as a difference in power at the wheels. This difference isn't the actual gain though....it's more of an inherent flaw in the way a dyno measures power. It will vary depending on how heavy the actual drum on the dyno is, for example....

 

ok so

if i took a stock b16.....put a lightned flywheel and tested it on an engine dyno then wheel dyno there would be a difference in power?

 

Think about it this way... It takes power to accelerate the flywheel, just like it takes power to accelerate the car.

The numbers are made up, but here's the idea.
Say it takes 4 hp to accelerate a heavy stock flywheel, but it only takes 2 hp to accelerate the light flywheel. That extra 2 hp is said to be 'drivetrain loss'. So when you put on the light flywheel you 'get it back'. Or more accurately, your flywheel doesn't use it up.

Now you go to a different dyno, which has a big drum that weighs a lot more than the first dyno. Now your stock flywheel takes 2 hp to accelerate while your light flywheel takes 1.

Then you find a dyno that has a big brake attached to the drum, so it actually measures wheel HP at a truely constant speed. Now there's no measurable difference between the 2 flywheels.

 

An inertial dyno (like a Dynojet) will show gains with a lightened flywheel. But a water brake dyno (like a Dynapack) will not.