Crank Pulley vs. Under-drive Pulley?
01-05-11, 05:30 AM
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Crank Pulley vs. Under-drive Pulley?
Hi Everyone,
Happy New Year! My crank pulley fell apart the other day and I was looking into under-drive pulleys. Can anyone tell me the pros and cons to them. It is cheaper than getting a crank pulley so that was the real reason that I was looking at them. Thanks for your help!
Happy New Year! My crank pulley fell apart the other day and I was looking into under-drive pulleys. Can anyone tell me the pros and cons to them. It is cheaper than getting a crank pulley so that was the real reason that I was looking at them. Thanks for your help!
01-05-11, 09:19 AM
#2
pros-you might gain 1hp
cons-it will destroy your engine
the factory pulley is whats called a harmonic balancer/crank damper. Its actually two pieces held together by rubber as you have found out.
Every time the cylinders fire, torque is imparted to the crankshaft. The crankshaft deflects under this torque, which sets up vibrations when the torque is released. At certain engine speeds the torques imparted by the cylinders are in sync with the vibrations in the crankshaft, which results in a phenomenon called resonance. This resonance causes stress beyond what the crankshaft can withstand, resulting in crankshaft failure.
To prevent this vibration, a harmonic balancer is attached to the front part of the crankshaft. The damper is composed of two elements: a mass and an energy dissipating element. The mass resists the acceleration of the vibration and the energy dissipating (rubber/clutch/fluid) element absorbs the vibrations.
there are 4 pulleys to my knowlege that you can use safely
1. the stock pulley - cheapest option
2. fluidamper - sold at summit racing
3. ATI damper pulley - this is the most commonly used aftermarket pulley (it does require a different belt though)
4. Boostlogic makes a nice dampered pulley
cons-it will destroy your engine
the factory pulley is whats called a harmonic balancer/crank damper. Its actually two pieces held together by rubber as you have found out.
Every time the cylinders fire, torque is imparted to the crankshaft. The crankshaft deflects under this torque, which sets up vibrations when the torque is released. At certain engine speeds the torques imparted by the cylinders are in sync with the vibrations in the crankshaft, which results in a phenomenon called resonance. This resonance causes stress beyond what the crankshaft can withstand, resulting in crankshaft failure.
To prevent this vibration, a harmonic balancer is attached to the front part of the crankshaft. The damper is composed of two elements: a mass and an energy dissipating element. The mass resists the acceleration of the vibration and the energy dissipating (rubber/clutch/fluid) element absorbs the vibrations.
there are 4 pulleys to my knowlege that you can use safely
1. the stock pulley - cheapest option
2. fluidamper - sold at summit racing
3. ATI damper pulley - this is the most commonly used aftermarket pulley (it does require a different belt though)
4. Boostlogic makes a nice dampered pulley
01-05-11, 10:18 AM
#4
ahhh you sir are correct
Boostlogic
http://www.boostlogic.com/xcart/prod...9&cat=5&page=1
Titan
http://www.titanmotorsports.com/timoda2jcrpu.html
Fluidampr
http://www.summitracing.com/parts/FLU-840801/
ATI
http://www.summitracing.com/parts/ATI-918562/
Boostlogic
http://www.boostlogic.com/xcart/prod...9&cat=5&page=1
Titan
http://www.titanmotorsports.com/timoda2jcrpu.html
Fluidampr
http://www.summitracing.com/parts/FLU-840801/
ATI
http://www.summitracing.com/parts/ATI-918562/
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