Well since someone else agreed with me um yea I'm sure.

Yep...I still think you are wrong, since per your claim he is involved in 99.9% and that information is incorrect.

... perhaps you should both head over to the Puffies are OK thread ... calms me down.

Just kidding...so someone posted a 17% loss based on the fact the Z has a shorter and lighter drive shaft than normal RWD cars ? Fact or fiction ?

And just curious, is there anything in the drive train that can change to reduce the loss ?

:shakes head:


Lets stop and not kill this thread.

I remember reading in another thread here, months ago, that someone reduced their rear tire/wheel/rotor combo weight and it showed up as an increase on the dyno. I don't remember the specifics. It could have been a reduction in weight of any of the three.

If this is true then I would love to see the charts, and see the weight drop vs. the increase.

If a lighter weight driveshaft reduces hp loss to the road, then it does seem that lighter weight wheels, tires, and/or rotors would do the same.

I have read reduced weight = HP gains, but not sure if that would actually translate to a dyno. Be nice if it did.

From results posted, the reduced weight crankshaft pulley shows up as a gain on the dyno.

And apparently the lighter weight driveshaft does too, if we are indeed around 17% loss vs. 20%. That claim is speculative of course as you can't prove it (unless you would actually change the driveshaft).

So why not for the wheels/tires/rotors?

Here is the part that boggles me. If all four corners are reduced in weight, and you do see a gain at the dyno, would the gain actually be MORE because you can't dyno the front?

If the answer was yes I would be shopping right now for lighter weight tires, rotors, and wheels.

I guess everyone who knows anything left here to go look at Puffies. :tup:

I mean if that were true, then guys would be taking the spare tire and everything out to do dyno runs. I'm not so sure it translates to the dyno.

Not the spare tire. The results I've read about but never saw charts to prove, was in reducing the rotational mass of the tires, wheels, rotors, or all.

Just like the rotational mass of the pulley affects the wheel horse power. Peak HP isn't increased, but more is delivered to the wheels (less loss).

I'm in a lease right now, so am looking for ways to deliver more power without serious mods. I don't know if I would have to reduce the mods at the end of my lease, if I don't buy the car.

So far I only have K&N filters and plan to soon buy the post MAF tubes. Not serious mods and easy to reverse if need be.


So reducing rotors and tires would be fine, they are normal wear items. And reducing the wheel weight would also most likely improve the value so that shouldn't be an issue. But I'm only going to do it if there is a noticed improvement.

I've already shopped around and found that I can buy all - new tires, rotors, and wheels - and reduce the rotational mass by over 60 pounds total. I just don't know how that will relate to acceleration improvement.

Now I am guilty of taking this off topic. Sorry. For some reason I felt the need to explain myself. It won't happen again.

Bingo! I think I see where we differ in perspective. The OP was referring to percentage increase over the Dyno number. Which to get a 25% 'increase' to get you that flywheel number, you would use 1.25. Since you don't technically know that 73hp difference, you have to use the percentage increase over the dyno number. Like I've said twice now. I never said you were wrong. It's a 20% loss over the flywheel number but 25% gain over the Dyno number. I think we're just mixing symantics when referring to 'drivetrain loss'.

Eh you asked the first question, your thread. I think I read one of the track saavy guys post that every 10 pounds lost equated to 1 HP ... but I could be wrong it was awhile ago I read that, and can't recall what thread it was. If true, dropping 60 is not really going to net you a ton of power. Again I am going from memory, so that could be wrong.

I read that too, Sixpax. It was in the weight reduction thread, which I've read a few times now. It was for overall weight, and is like you said, equivalent to HP gain but not actually a gain.

For rotational mass reduction though, it will also have the equivalent gains due to lower weight, but also - from what I've read - will actually deliver more HP to the wheels. And at a better ratio than 10 to 1. Nobody though has posted before and after numbers. I may have to be the first to try it.

The lightweight pulleys are about 4 pounds less weight and deliver about 5 more HP to the wheels.

you "correct" him and say that his 1.25 figure is 25%, when his reference is clearly to drivetrain loss.
http://img.tapatalk.com/a6937cb5-c48a-4fe8.jpg


If you had understood from the beginning, you'd have just agreed....

My bad ... I finally focused on your "rotational mass" reference ... I was hung up on any weight loss ... seems easy to test if you dyno with the rear wheels you have, and then slap some lighter ones on.