Hammond drives the GT500

[SVT666]

Sounds like you're getting a bit snippy about it.

I don't intend to sound arrogant, but the three of us (SoupDeVille, MX793 and myself) that are in agreement that a lighter driveshaft and/or flywheel does not increase RWHP each have a mechanical engineering degree.

Yes you do sound arrogant.  Did you read my last post where I admit that I must not be understanding something?  Obviously not.

[SVT666]

While most of the car isn't moving at all when strapped to a chassis dyno, parts of it are undergoing an acceleration, and thus a change in kinetic energy.? Which parts?? All of rotating bits in the drivetrain (wheels, driveshaft, flywheel, clutch, etc).? Inertial chassis dynos work by measuring accelerations, then multiply by moment of inertia (which is a mass or weight term) to figure out the power.? If you reduce the moment of inertia of the system by reducing the weight of the rotating pieces, you'll get more rotational acceleration in the rotating bits for the same power, just as if you reduce the vehicle as a whole you'll get better acceleration at the drag strip.? But if you don't change the moment of inertia parameter in the dyno's computer to reflect this reduction in rotating mass, it will falsly read that you're generating more power because the dyno is measuring greater drum acceleration and, as far as it knows, the rotating mass in the system is the same as before.

This makes a bit more sense to me.  Thanks.

[GoCougs]

I have three quarters of a mechanical engineering degree, and I say a lighter driveshaft and/or flywheel can increase RWHP...

... fractionally, because friction losses would hypothetically be smaller. If the parts are lighter then, hypothetically, you won't lose as much energy to the bearings, etc.

But the difference is probably negligible at best.

This is very astute. I'd counter that it is possible that the load (and hence friction) would not be seen as tranny/diff pinion bearings have a good amount of preload on them. Either way, at best it's probaby on the order of 0.0000001 RWHP. Of course, if we want to go down that esoteric road, any electrical item; headlights, radio, heater fan, similarly consumes ultra minute amounts of RWHP as well.

[SJ_GTI]

I like that "The Nethead" keeps referring to Lebowski as Leblowski.

[SVT666]

I like that "The Nethead" keeps referring to Lebowski as Leblowski.

[MX793]

I like that "The Nethead" keeps referring to Lebowski as Leblowski.

haha, good catch.

[Raza]

The only problem with their testing is that the tests are done on different days.  I've seen them test on super cool days, rainy days, and on scorching hot days.  The cars running on the super hot days will generate more grip but engine power suffers.  On the cool days the cars don't get as much grip but they produce more power.  The rainy days speak for themselves.

So you take the numbers with a little bit of salt.  A difference that small I'd consider even.

[GoCougs]

Yes you do sound arrogant.? Did you read my last post where I admit that I must not be understanding something?? Obviously not.

You did as well. No harm either way.

[93JC]

This is very astute. I'd counter that it is possible that the load (and hence friction) would not be seen as tranny/diff pinion bearings have a good amount of preload on them. Either way, at best it's probaby on the order of 0.0000001 RWHP. Of course, if we want to go down that esoteric road, any electrical item; headlights, radio, heater fan, similarly consumes ultra minute amounts of RWHP as well.

I read an essay against daytime running lamps a couple years ago that extrapolated the load necessary to keep the lights on all the time and subsequently fraction of extra fuel consumption "wasted" on the lights.

All ridiculous bullshit, of course, but it was funny.