Effective NA Power Mods

[DSLeach]

Originally Posted by Tcoat

This is debate #182,036 on this subject. And you rather rudely call out the leader of the opposition. He can out rude you though so this could be interesting.

Rude? I don't think anything I said was rude. Besides, there should be no debate on this subject. It is just simple physics.

[Mim]

Originally Posted by go_a_way1

Does your driveshaft make much noise?? I am looking at getting on simply because its one piece. And get lighter wheels makes big difference on how your suspension reacts to the road that's a step in the right direction

No noise in regular driving though I do hear an occasional clunk when I throw it in reverse. Certainly the sort of mod I'd want to do to future cars without any hesitation.

[Tcoat]

Originally Posted by DSLeach

Rude? I don't think anything I said was rude. Besides, there should be no debate on this subject. It is just simple physics.

I think the whole "By the way, where did you get your engineering degree?" is pretty rude actually.

No disputing that the reduction of rotating mass will make a difference. The bigger concern for the sake of the subject at hand is how big a difference. Saving 4 ounces on a light weight pulley is NOT going to make a difference that is even measurable on any form of test equipment outside of a major lab. I doubt you could reduce the weight (at least with any form of budget in mind) of enough rotating components in the engine these cars to make a measurable difference much less the claims of some that the car "comes alive".
The physics is one thing, the application of them at the level of lightweight pulleys is another.

[gramicci101]

Originally Posted by DSLeach

Rude? I don't think anything I said was rude. Besides, there should be no debate on this subject. It is just simple physics.

It is simple physics, but "lighter rotating mass=more power to the ground" is almost too simple, because it ignores a lot of side effects. Pulleys especially are hotly debated for the side effects they may or may not cause to the smooth and long-term operation of the engine. A lighter flywheel does free up power to be put to the ground, but its effects on shifting are pretty well recognized. Lighter wheels are pretty straightforward, but they're also unsprung mass, which affects how the suspension is going to operate. A single piece CF driveshaft is awesome, but that OEM center bushing is there for a reason. Removing it from the chain potentially introduces NVH or balance issues. Freeing up rotating mass is a great idea, as long as the side effects are taken into account. I'm a proponent of stiffer drivetrain bushings to keep the non-rotating parts, like the transmission and diff housings, from rotating under torque. But that causes NVH.

[justatroll]

Originally Posted by DSLeach

I would also note that because a chassis dyno measures wheel horsepower, none of the parasitic losses in the engine and drive train (friction and losses to accelerate rotational mass) will show up on the dyno results. If you are able to reduce the rotational mass of the engine and drive train, you will get a higher HP reading on the chassis dyno. Less power used to accelerate rotating mass means more is available to spin the dyno drum.

Cheers!

No you still will not.


Which part are you not understanding about:
HP measurements (engine OR chassis dynos) measure torque at discrete (STATIC) RPMs.
How does the rotating mass affect the torque measurement at static (non-accelerating) RPM?
Answer (again) it does not.


Torque is just the FORCE being applied to an object with a Mass.
How does the mass of the object affect the force being applied to it? It doesn't!


Again, dynos do NOT measure how fast you can change RPM.
They measure ONLY the torque applied while at a static RPM.
A dyno measurement is NOT a race from one RPM to another.

[DSLeach]

Originally Posted by Tcoat

I think the whole "By the way, where did you get your engineering degree?" is pretty rude actually.

No disputing that the reduction of rotating mass will make a difference. The bigger concern for the sake of the subject at hand is how big a difference. Saving 4 ounces on a light weight pulley is NOT going to make a difference that is even measurable on any form of test equipment outside of a major lab. I doubt you could reduce the weight (at least with any form of budget in mind) of enough rotating components in the engine these cars to make a measurable difference much less the claims of some that the car "comes alive".
The physics is one thing, the application of them at the level of lightweight pulleys is another.

Indeed, your pulley discussion is correct in that you won't be able to measure the small amount of power freed up by using a slightly lighter pulley. It's simply not that large of a component in terms of diameter or mass.

But dropping 10 lbs off your flywheel, especially if the mass is removed from the outside diameter of the flywheel, will make a small but measurable difference. Likewise, dropping a couple pounds off each wheel/tire will make a small but measurable difference.

The reason I challenged the original post is because the following statement

"It is NOT POSSIBLE to get "more hp" by reducing the rotating mass of the engine or drivetrain.
It does not Make more HP or "free up" more HP.
Removing weight from the rotating mass will give you the exact same benefits as removing that same weight from anywhere else on the car."

is simply not correct. Lowering the rotational mass of the drive train will most definitely "free up" HP that is then available to provide higher linear acceleration to the vehicle.

Cheers!

[Tcoat]

Originally Posted by DSLeach

Indeed, your pulley discussion is correct in that you won't be able to measure the small amount of power freed up by using a slightly lighter pulley. It's simply not that large of a component in terms of diameter or mass.

But dropping 10 lbs off your flywheel, especially if the mass is removed from the outside diameter of the flywheel, will make a small but measurable difference. Likewise, dropping a couple pounds off each wheel/tire will make a small but measurable difference.

The reason I challenged the original post is because the following statement

"It is NOT POSSIBLE to get "more hp" by reducing the rotating mass of the engine or drivetrain.
It does not Make more HP or "free up" more HP.
Removing weight from the rotating mass will give you the exact same benefits as removing that same weight from anywhere else on the car."

is simply not correct. Lowering the rotational mass of the drive train will most definitely "free up" HP that is then available to provide higher linear acceleration to the vehicle.

Cheers!

See that is my issue whenever this damned pulley conversation comes up. It always gets extended to many other components and then their overall affect is considered the equivalent to reducing pulley weight. Just not so.

[DSLeach]

Originally Posted by justatroll

No you still will not.


Which part are you not understanding about:
HP measurements (engine OR chassis dynos) measure torque at discrete (STATIC) RPMs.
How does the rotating mass affect the torque measurement at static (non-accelerating) RPM?
Answer (again) it does not.


Torque is just the FORCE being applied to an object with a Mass.
How does the mass of the object affect the force being applied to it? It doesn't!


Again, dynos do NOT measure how fast you can change RPM.
They measure ONLY the torque applied while at a static RPM.
A dyno measurement is NOT a race from one RPM to another.

I'm not going to continue this discussion because you clearly don't have the necessary education to understand the physics of this subject.

[gramicci101]

Try a little harder to flaunt your degree next time, ok?

[nikitopo]

This is the calculator @DSLeach mentioned before. Even the OEM crank pulley stores enough energy:




I guess the actual energy is somewhere between the Disk and Ring outputs, because a lot of the mass of the pulley is on the external side.


Have fun with the rest of the discussion. I am logging off.

[justatroll]

Originally Posted by DSLeach

I'm not going to continue this discussion because you clearly don't have the necessary education to understand the physics of this subject.

Just please explain where I am wrong.


Oh that's right you cant.

[M-17]

[strat61caster]

Originally Posted by DSLeach

I'm not going to continue this discussion because you clearly don't have the necessary education to understand the physics of this subject.

BS in Mechanical Engineering from a public university that ranks well and typically gets called a 'Public Ivy'.

Somebody shortchanged you on your education.

[Tcoat]

Originally Posted by nikitopo

This is the calculator @DSLeach mentioned before. Even the OEM crank pulley stores enough energy:




I guess the actual energy is somewhere between the Disk and Ring outputs, because a lot of the mass of the pulley is on the external side.


Have fun with the rest of the discussion. I am logging off.

That is wonderful but as much as a pulley LOOKS like a flywheel its is most certainly NOT one. The calculation there is meaningless.

fly·wheel
ˈflīˌ(h)wēl/
noun
noun: flywheel; plural noun: flywheels; noun: fly-wheel; plural noun: fly-wheels
a heavy revolving wheel in a machine that is used to increase the machine's momentum and thereby provide greater stability or a reserve of available power during interruptions in the delivery of power to the machine.