What is under drive pulley and how does it look like?

 

Underdrive pulleys are pulleys that you swap onto your engines accessories if you run your engine at high RPM a lot. They are bigger than the normal pulleys and therefore wont run them as fast but it will save the engine power. You could put an underdrive pulley on the alternator, smog pump, an d probably some other things. "underdrive" just means you are under driving them from their factory specs. Youre not running them as fast so your engine doesnt have to expend as much energy turning the accessories. It may save some power, I dont know how much. Maybe like 10hp. I dont know.

 

part true. the crank pulley is smaller than stock. the alternator and water pump is larger. think like a ten speed bike. the crank pulley is the pedal gears. it is easier to turn the pedal with the smaller sprocket. this is called the drive pulley. the alt and wate are the driven pulleys. just like the gears on the rear wheel, the bigger, the easier it is to turn.

on my '95 3.4v6 camaro, i had it dyno'ed at superchips in longwood,fl. it picked up 10.5 hp at the rear wheels. the downside to underdrive pulleys is that the alternator is turning slower. so at idle, the alternator isn't charging. i ran then on my car for over a year with no problems with the charging system.

 

now I get it. I thought of it as a pulley that turn some assecories backwards....


Thanks...

 

mrr, so are you havingt problems with your charging now?

 

 

no. i sold the car three years ago. but never had any problems.