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can someone please help me what is the diffrence between
underdrive and overdrive pully's advatege's and disadvantage's
underdrive and overdrive pully's advatege's and disadvantage's
overdrive & underdrive pullys
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21,139 Posts
basic high school geometry and math :
it's the circumference of a circle and how the radius determines circumference.
if you reduce the radius on a pulley (UNDERpulley), the distance for 1 revolution (circumference) is lowered. So the for example on a PS pulley, there is a certain amount of power used to turn one revolution. If you make the distance to travel for 1 revolution smaller, the power needed to complete it will be less. This frees up power to be used to turn the crankshaft instead. Less parasitic power loss. Obviously an overpulley has the opposite effect.
That's the theory anyway. In reality, do we see huges gains with them? nope. IMHO they are a waste of time and money...I stay away from crank underpulleys since I believe the Honda crank pulley IS a harmonic balancer for the crankshaft (others don't and slap one on...your choice..I won't debate it with someone since it's their car and a free country). I have the AEM AC and PS underpullies (got hyped way back in 1998 when these first came out). When we dyno'd my car after the underpullies install they made no gains. The most I've seen gained by them on an integra is 1-2 whp...not more. As I said, a waste of time and money. People have gained 4-6 whp with the crank underpullies...but I'm not willing to subject my engine to the risk.
cheers
it's the circumference of a circle and how the radius determines circumference.
if you reduce the radius on a pulley (UNDERpulley), the distance for 1 revolution (circumference) is lowered. So the for example on a PS pulley, there is a certain amount of power used to turn one revolution. If you make the distance to travel for 1 revolution smaller, the power needed to complete it will be less. This frees up power to be used to turn the crankshaft instead. Less parasitic power loss. Obviously an overpulley has the opposite effect.
That's the theory anyway. In reality, do we see huges gains with them? nope. IMHO they are a waste of time and money...I stay away from crank underpulleys since I believe the Honda crank pulley IS a harmonic balancer for the crankshaft (others don't and slap one on...your choice..I won't debate it with someone since it's their car and a free country). I have the AEM AC and PS underpullies (got hyped way back in 1998 when these first came out). When we dyno'd my car after the underpullies install they made no gains. The most I've seen gained by them on an integra is 1-2 whp...not more. As I said, a waste of time and money. People have gained 4-6 whp with the crank underpullies...but I'm not willing to subject my engine to the risk.
cheers
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Michael Delaney on Aug/15/02 said:
If what??? Oh no, his brain has overloaded and shut down...everyone, prepare to jump...
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18,513 Posts
Oh thank God, he rebooted and finished...hehe, just giving you a hard time MD for pushing that post icon a bit too early.
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