Originally Posted by Civic2Scooby
this is utter and complete dogshit...and yes there are drawbacks to underdrive pulleys...changing the diameter of a pulley greatly increaes wear on parts that were designed with a different pulley size intended to spin them within a certain range. Also the underdrive crank pullies manufactured are nowhere near as well balanced as the stock pulley. You can end up doing alot of damage. Also this claim of 5whp from an underdrive pulley is utter and complete bullshit.
Okay okay... wow i better not drive fast if these items (a.c. and p/s) need to be operated at a certain speed. According to your logic, faster speeds, turbo, superchargers would destroy everything that the crankshaft spins.
These systems are driven by the crankshaft speed. Also the Alternator is NOT underdrived by these pulleys on several models.
They're not harmonically balanced, that will only reduce longevity in the long run. I don't think people mod their engines for racing and expect it to last for ever. 5whp isn't a lot but it's been proven on the dynojet and for the price it's nice.