Lightweight pulley wow

[Ranatsu]

Originally Posted by wlfpck

Definitely, I agree with you.

The other thing to note to... and this gets into some of the physics stuff that I was talking aobut...

At least for the Scion tC, the reason that a decent number of people have not seen a problem for 50k miles is that the engine was never revved high enough. For the supras and such that reported a problem, they are dealing with revving much higher. Could this be a problem? The physics behind it indicate that this is one cause. Could there be more reasons? Maybe. Maybe not.

But yeah. I definitely agree. It would be nice if a company that makes these lightweight crank pulleys actually showed video/photo of their testing phase and R&D like companies like AIR RAID and others have done.

I wonder if anyone has contacted Fluidampr or ATI about producing a replacement pulley.

[brichard0625]

By the way on the 22nd im going to do a before and after dyno on the perrin pulley...lets see what the dyno says

[wlfpck]

Originally Posted by brichard0625

By the way on the 22nd im going to do a before and after dyno on the perrin pulley...lets see what the dyno says

Depending on what type of dyno it is using, it could show a "gain" in power.

The key thing to remember is this...


The crank pulley does NOT free up horsepower.

For instance...

Your car is measured to be 160 hp at the crank. Put on the lightened crank pulley and it will STILL read 160 hp at the crank.

The only reason it shows up on a dyno that you have "gained" horsepower is because the dyno is inertia based. By using a lightened crank pulley, you reduce the amount of weight the engine has to turn.

After you install a lightened crank pulley, your engine still makes the same amount of power. You are simply just lightening the amount of weight the engine has to turn.

You can achieve the same with lighter wheels. Your engine still makes the same amount of power. It just simply has less amount of mass to rotate. For that reason, you will be faster. However, your engine does not make more power.

[whataboutbob]

Originally Posted by wlfpck

Depending on what type of dyno it is using, it could show a "gain" in power.

The key thing to remember is this...


The crank pulley does NOT free up horsepower.

For instance...

Your car is measured to be 160 hp at the crank. Put on the lightened crank pulley and it will STILL read 160 hp at the crank.

The only reason it shows up on a dyno that you have "gained" horsepower is because the dyno is inertia based. By using a lightened crank pulley, you reduce the amount of weight the engine has to turn.

After you install a lightened crank pulley, your engine still makes the same amount of power. You are simply just lightening the amount of weight the engine has to turn.

You can achieve the same with lighter wheels. Your engine still makes the same amount of power. It just simply has less amount of mass to rotate. For that reason, you will be faster. However, your engine does not make more power.

For anyone who might care to read a bit more on the related physics associated with this subject:

http://en.wikipedia.org/wiki/Angular_momentum
http://en.wikipedia.org/wiki/Moment_of_inertia

I agree that the pulley does not increase the horsepower, but it probably does reduce the parasitic losses as that horsepower is transferred to the ground.

[wlfpck]

Originally Posted by whataboutbob

For anyone who might care to read a bit more on the related physics associated with this subject:

http://en.wikipedia.org/wiki/Angular_momentum
http://en.wikipedia.org/wiki/Moment_of_inertia

I agree that the pulley does not increase the horsepower, but it probably does reduce the parasitic losses as that horsepower is transferred to the ground.

Exactly.

That's why the same thing can be achieved with lighter wheels.


Though... on that note...

The Altenator pulley and the water pump pulley can be replaced with lighter ones as these are not dampened (at least the tC ones are not. I can not say for sure these are not).

Though... if you're going for maximum rotating mass reduction...

a lightened flywheel will be a lot better than a crank pulley.

[d1ce]

basically a lighter flywheel shaves weight off the entire car, and the weight reduction is more pronounced in first gear, a little bit less in 2nd gear and so on. same as the pulley.

http://www.uucmotorwerks.com/flywhee...heel_works.htm

[DEnd]

Originally Posted by whataboutbob

I agree that the pulley does not increase the horsepower, but it probably does reduce the parasitic losses as that horsepower is transferred to the ground.

Not exactly. It doesn't increase horsepower during a steady state (how most bhp dyno read), it does increase horsepower during acceleration (how an inertia dyno reads). Remember how you measure something is just as important as what you are measuring for a given task.

[wlfpck]

Originally Posted by d1ce

basically a lighter flywheel shaves weight off the entire car, and the weight reduction is more pronounced in first gear, a little bit less in 2nd gear and so on. same as the pulley.

http://www.uucmotorwerks.com/flywhee...heel_works.htm

Anything lighter than the OEM will create weight reduction overall to the entire car.


The reason the lighter flywheel is safer and better is that...

1) The stock flywheel is not dampened. The stock pulley is.
2) Look at the diameter of the flywheel compared to that of a crank pulley. You're reducing the rotational mass. However, because the diameter of the flywheel is much larger than that of the pulley, you're reducing more rotational mass and you will get MUCH better benefits with a lighter flywheel. And this is without the risk of a undampened pulley.

[killercl0wnfish]

So im swapin mine out and i notace that the bolt is real "sloppy" goin in almost like its not thick enuff .... is this normal.... i checked the bolt and it shows no signs of abuse

[ScionRacer]

The effects the lightened pulley offer can be achieved with lighter wheels/tires as stated previously with no effects to engine reliability.Any changes in rotational mass from the crank to the rear tire will effect engine powerband,not engine power output.

If gains in hp are made,they are miniscule.The advantage is the hp comes on faster,the "hit" is much harder.the power is being made less linear and more peaky.

The downside to too much lightening is the engine will struggle in raised elevation changes and the lost momentum would keep the engine out of the torque band.

[Mikepage]

Bump to inform users, very good thread with a lot of good information!

[Blighty]

Hey, I dont know a lot about this, but isn't the reason for harmonic balancing on small engines only due to the pulley having poor manufacturing tolerance that can cause an unpredictable of harmonic frequency?

These lighter ones on offer should certainly be very 'balanced', they are machined out of a single piece of billet aluminium right? No two/thee piece casted stuff.

[Blighty]

Originally Posted by ScionRacer

The downside to too much lightening is the engine will struggle in raised elevation changes and the lost momentum would keep the engine out of the torque band.

Aren't you talking about lightening a flywheel here? The flywheel stores the rotation energy... The pully is just for direct transfer of energy. Or so I thought.

[breezy]

Originally Posted by Blighty

Hey, I dont know a lot about this, but isn't the reason for harmonic balancing on small engines only due to the pulley having poor manufacturing tolerance that can cause an unpredictable of harmonic frequency?

These lighter ones on offer should certainly be very 'balanced', they are machined out of a single piece of billet aluminium right? No two/thee piece casted stuff.

Crank pulley is also called a damper. Every time a piston is driven down on a power stroke, there is a torque spike in the crankshaft that twists it ever so slightly. After it is twisted, it will bounce back slightly, twisting the other way and continue to oscillate like this unless you have something to absorb this energy. The danger is when these oscillations occur at the crank's resonant frequency, and the oscillations grow in magnitude, which may compromise the crank.

The damper serves to absorb this energy (by different means depending on the type of damper). Most feature vulcanized rubber that absorbs this energy and dissipates it in the form of heat.

This is why I, and similarly most OEM engine manufacturers, believe a crank pulley with damping is necessary.