I see that there are different pulleys, some are just lighter than the oem part and some are smaller in diameter. Who has any of these or anyone that knows about these products please comment. Thanks

 

Not sure how you would need a smaller, or bigger pulley, unless for a sc, but lighter ones are uselfull if you really want to squeeze every bit out of the engine. Its a lot lighter, so less hp wasted turning them. Same theory for a lightened flywheel, but with less effect...

 

LOL @ the BMW

 

I can't remember what the small/bigg ones do but I think it is something like a mountain bike gear. . . . You know..... smaller the cog (or in this case pulley) the harder it is to pedal but the faster you can go. I'm pretty sure its that sort of crap.

 

the smaller it is the faster it will reva and will minimize the parasitic drag. also lighter is bad these engines where balanced by the germans so throwing it out of balance will just cause damage. now if u can get smaller pullies that weight the same do that. also if u find em let me know

 

I cans ee the point of getting smaller pulleys on a supercharger, but what other need would you have for altering the pulleys on an engine? Only pulleys I can think or would be to run ancillary items, and the timing gear. Why on earth would you want to make these smaller?

 

Most car companies dont ballance the engine with the pully on because if it has to be changed because of damage or rubber going out. (some cars have rubber bushings beteween center and belt groves) Then the vehicle would have to be rebalanced. the engines are balanced with the harmonic balancer though so dont remove that. also the weight doesnt have to be perfect because some shops have the flywheel resurfaced when changing a clutch. (eliminates hot spots on disk) I have replaced pullys on many different cars no audi's though and the new part just comes in a bag no special numbers.

 

Guy up there has it backwards... BIGGER accessory pullies (AC, power steering etc) will slow them down, and reduce drag.

These are called underdrive pullies, and on lots of cars can free up somewhere around 10 hp... it's also pretty good for your AC if you are rev happy, as your accessories will spin slower.

They are big on domestic cars... I never hear about underdrive pullies on audi's though. Hmm.

 

I wouldnt never put one on my car, but alot of cars they work well with. The gains will be more as you add more hp in theroy.

 

Yeah.