Im trying to learn as I read about all the differnt parts and aspects from both the board and shooping around the parts stores. Just wondering about what Underdrive Pulleys and Timing chains do for performance or to make the car better than stock. Thanks!

 

Underdrive pulleys theoretically increase horsepower by reducing the amount of power required to drive external accessories, such as the alternator, power steering pump, crank pulley, ect. The gains offered by underdrive pulleys is very small and too most, not worth the money. As for the timing chain, a timing chain will not add horsepower. However, if you build up a motor that spins alot higher in rpms, then a stronger aftermarket timing chain becomes very beneficial to have.

 

technically an underdrive pulley doesn't increase hp...it reduces the amount of hp lost to parasitic drag on the engine....cause by the accessories.

so you aren't making more power, you're just losing LESS...

typical gains are around 2hp and 5-7# of torque at the wheels. but most seem to say that it allows the engine to spin up faster...but that's pretty subjective.

as for the chain...agreed..not really a hp upgrade. just a boost in strength and reliability.
although if your engine has some miles, the chain may be worn out, which could be throwing off timing a small amount. so it IS possible to pick up power.

 

The engine can't "spin up faster" unless it's making more torque. That placebo effect is right up there with ...."no increase on the dyno or the track, but is has better throttle response"..... uhhh, no.

How about if he types "theoretically increase horsepower at the flywheel"?

 

thanks for the info! much appriciated. What would be some good upgrades for boosting performance?