do0dfromcali

I was reading online that the underdrive pulley robs your alternator and waterpump of power to give the motor more horsepower.

I dont know if it is just me, but that sound bad.

If this were to go on a completly stock hemi, would it be able to handle it no problem?

LesPaul

the underdrive pulley kit comes with a larger alt. pulley to keep it charging at idle.. as for the waterpump i think that is crazy talk

Ram4Pick

I've used underdrive pullies on my last two trucks, Silverados, without a problem. They do free up some power. However, there's been talk that the Hemi engine has had the toner ring fail on them, alot of the trucks had underdrive pullies on them when the toner rings failed. The speculation is that the underdrive pullies increase vibration at very high rpm's and that's whats causing the toner rings to fail. Now, this hasn't been proven as fact but it's happened enough that I won't be putting an underdrive crank pulley on my truck.
Jim

Toe

Same here, no pulley for me because of the toner ring issues. over 3/4's of the trucks that have toner ring failures have had the pulley.

do0dfromcali

Sweet....Thanks for the info. I'll tell my buddy to stay away from it. Thanks for the info guys

ktmrider

I agree, stay away from the UD pullies on the Hemi. Too many toner ring failures to be coincidence. An electric fan would give the same or better benefits IMHO.
As far as UD pullies in general are concerned, the WP and sometimes ALT do turn at a slower RPM than stock. If you are on the edge of your cooling system capacity then you could experience overheating problems. Overall they are a viable power adder that I would install on anything BUT the 5.7L Hemi motor.

1Red Dawg

Yeah I was going to buy just the crank UNDP and started to read up on them first! After reading about the toner ring failures I decided not to get one!

HELLAFASTHEMI

I have a MOTOBLUE underdrive pulley sitting in my cloest because of toner ring failure. IMO save your money and get some NOS>