Lightweight pulley wow

[Blighty]

Originally Posted by breezy

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.

Interesting. Thank-you.

I guess with that example, the question that has to be asked is why do OEM cars sometimes not have one, and instead use a part similar to the ones provided by after-market. I.E machined and very light, but no dampener.

This is all physics, so there must be a reason.

[Blighty]

Originally Posted by karma003

All I see that telling me is the info I already know. The need for counter weights & balancing the motor. I don't see y any configuration would be different from the other. All motors where ment to fire in sequence, otherwise they'd be more prone to self-destruct. Maybe uneven firing orders like 3cyls & 5cyls I could understand the uneven forces & the loss of balance. But in even number motors I don't see that happening.

I think you will find that boxer engines have a natural dynamic balance.

So do straight 6's and v12's.

That's as far as my understanding goes though =D

[FreshFRS]

Originally Posted by Blighty

I think you will find that boxer engines have a natural dynamic balance.

So do straight 6's and v12's.

That's as far as my understanding goes though =D

What this guy says is correct. you can also lump V-8s (firing order dependent), in the category of naturally balanced. straight 6 and v12's are usually the best balanced however lots of area to spread out the forces. subies have been running super light crank pulleys since before i was born and there have been very few issues with it.

on another note i live at sea level! GFB pulley set and Light flywheel with a Carbon driveshaft for me!