OK, to start out, I didn't know these pulley kits even existed until a few days ago but now I have spent hours researching them to see if the kits are worth it. I can definitely see dyno proof online that suggests 8-10HP gains but then I see horror stories as well. So my opinion is; Not Worth It and here's why.
Essentially, the gains come from decreasing the overall parasitic drag on the engine from all the belt driven accessories such as AC compressor, Pwr Steerg pump, Alt. & Water pump/Fan. These pulley kits often replace the stock pulleys with larger and lighter ones to slow down the accessory or "underdrive" it. Some also replace the engine crank pulley/harmonic balancer with a smaller one (and sometimes no dampening characteristics) to further slow down the driven components. So you are not really gaining horsepower, just shifting more of it to the wheels by making it easier for the engine to turn spin the belt driven stuff.
In the end, you can solve this easier and cheaper by: 1) turn the AC off; clutch disengages=no load 2) decrease your overall electrical load; alternator is regulated and only takes what it needs to supply enough amps=fewer amps smaller load 3) Install eletric fans if you have the clutch/belt driven one=less constant dynamic load on the engine but more on the self-regulated alternator when the fans are needed (refer back to Alt.) 4) Power steering; well if you need the horses that bad just omit it and pump iron so you can steer manually.
As for me; I like for my water pump and AC to turn fast enough to keep the engine/me cool. Not gonna try to manaully steer a 6K# truck with a 7K# RV behind it. I like for the steering to work effortlessly when I'm manuevering my RV at low speeds to. Conclusion: IMO Perf. UD pulleys are OUT!
What Do You Think?
Essentially, the gains come from decreasing the overall parasitic drag on the engine from all the belt driven accessories such as AC compressor, Pwr Steerg pump, Alt. & Water pump/Fan. These pulley kits often replace the stock pulleys with larger and lighter ones to slow down the accessory or "underdrive" it. Some also replace the engine crank pulley/harmonic balancer with a smaller one (and sometimes no dampening characteristics) to further slow down the driven components. So you are not really gaining horsepower, just shifting more of it to the wheels by making it easier for the engine to turn spin the belt driven stuff.
In the end, you can solve this easier and cheaper by: 1) turn the AC off; clutch disengages=no load 2) decrease your overall electrical load; alternator is regulated and only takes what it needs to supply enough amps=fewer amps smaller load 3) Install eletric fans if you have the clutch/belt driven one=less constant dynamic load on the engine but more on the self-regulated alternator when the fans are needed (refer back to Alt.) 4) Power steering; well if you need the horses that bad just omit it and pump iron so you can steer manually.
As for me; I like for my water pump and AC to turn fast enough to keep the engine/me cool. Not gonna try to manaully steer a 6K# truck with a 7K# RV behind it. I like for the steering to work effortlessly when I'm manuevering my RV at low speeds to. Conclusion: IMO Perf. UD pulleys are OUT!
What Do You Think?
