What's a cam? What's a pulley? What's wrong with the stock ones that aftermarket ones make more power?

 

...a cam is a camshaft, do a search on howstuffworks.com for it

a pulley is a basic mechanical thing that multiplies force

 

Dont know too much about cams. From what I have read on here, the power gain from the pulleys is due to a reduction in weight on the crankshaft. I dont know if this is the right # but Im thinking the stock crank pulley weighs around 5 or 6 pounds whereas the UR pulley is several pounds lighter. The other 2 accessory pulleys are basically there for looks. They dont really serve a purpose as far as power gains are concerned. If Im wrong in this, someone please corect me.

Zach

 

I love helping out the newbies......

Basically a pulley reduces drivetrain loss. It doesn't necessarily make more power itself, but it reduces the power lost by turning the drivetrain and the accesories. This will allow the car to rev faster and it will accelerate faster.

I'm no expert on cams, I'll leave that to someone else.

 

The accessory pulleys add to the weight reduction only.

 

and a camshaft opens and closes the valve as they turn

 

[QUOTE]Originally posted by zachcrosen
[B]Dont know too much about cams. From what I have read on here, the power gain from the pulleys is due to a reduction in weight on the crankshaft. I dont know if this is the right # but Im thinking the stock crank pulley weighs around 5 or 6 pounds whereas the UR pulley is several pounds lighter. The other 2 accessory pulleys are basically there for looks. They dont really serve a purpose as far as power gains are concerned. If Im wrong in this, someone please corect me.

The additional benefit of the U/R is that it is a smaller Diameter than the stock pulley which results in a lower velocity on the belt which is driving the accessories (A/C and Alt.) The so called underdive, (approx 15%) does not have any significant affect on the operation of the accessories but provides the added benefit of less engine Tq to drive the accessories.

 

camshafts regulate air/fuel mixture, different lobe designs on the shaft create different timings for open and close valves

http://auto.howstuffworks.com/camshaft.htm

that's a REALLY detailed info. pictures too! =]