Just a quick question

Would upgrading the clutch and flywheel decrease drivetrain loss at all? so would the dyno numbers be higher?

lets say a 9.5 lb flywheel/6-puck clutch?

 

clutch no. flywhell maybe. feel the rev speed difference more than a measured power gain

 

No and No, although there is lower mass, it doesn't change the horse power produced. It will effect how fast the power is applied through the drive train though.

 

ok gotcha cool thanks

 

noone is saying it would produce more horse power...i think the question was would the rwhp on a dyno increase due to less drivetrain loss. I would think yes.

 

I would agree, with less rotational mass the drivetrain loss would also go down. How much you would gain might be very little but more none the less.

 

In 1st and 2nd gear, you should measure noticeably more rwhp with a light flywheel. However, dyno runs are correctly performed in 4th gear, where you a lightweight flywheel no longer has much advantage. Therefore, in a proper 4th gear dyno run, you most likely wouldn't notice more than a few hp difference, which is within the error of each run anyway.

 

Ok, I guess I should be more specific. His question was by upgrading his clutch and flywheel would he be reducing drive train loss thus gaining higher numbers.

My first answer was a quick response, it should of read No and maybe slightly. Let me explain, drive train loss is more a result of friction. The biggest losses are in the transmission and differential. Although rotational mass can have an effect, it is a very small part of the loss, unless of course the engine is considerably underpowered compared to the mass it is trying to rotate. For this proposes I would assume he is talking about an RX7 so this should not be an issue.

Now most chassis dyno’s are of the inertia type. So any reduction in inertia through the drive train will show increases (how ever small) in the readings. But the reality of this is not an increase in horsepower, just an increase in reported horsepower by the dyno. Most tuners will tell you that this increase is not why you would go through the expense of reducing the weigh of you flywheel or clutch. The real gain here is the reduction in time it takes to make peak power and the time it takes to accelerate to redline thus increasing overall performance.

Hope this explains it a little better,
Dan