i've been thinking about an underdrive pulley to help me get a little more power back to the wheels.

is this worth it in terms of power gains on a mostly stock '91 NA?

is this a risk for overheating a stock cooling system because it underdrives the water pump?

please weigh in if you have used or seen an underdrive pulley on a 7.

thanks

 

I use an unorthodox racing underdrive main pulley and also an underdrive greddy waterpump/alternator set on my FD... So I guess I'm double-underdriven... Works fine for me, but then again, I keep my revs up high so the water pump works OK for me. The lights DO dim at idle though so be aware of that.
Brian

 

me too, no probs, but don't look for much gain.

 

I got one to prevent cavatation of the water pump with a bridgeport engine. I am certain a water pump has a finite number of revolutions in its life with average rpm range from idle-7000rpm, lowering the number of times it spins slows down the rate at which it ages it(and you can rev well past 7000rpm without worrying about the cavatation problem occuring). I don't think it gives big gains in hp, just frees it to spin the rest of the engine a little bit more.

Coolant system will be adquate if it was working right before. Battery voltage/current charging should be fine as long as your not using it in stop/go traffic all day at 800rpm. Bridgeport idles at ~1900rpm, no worries for me.

 

I've got a full pulley set & it works fine with no problems nor lights dimming too much.

 

The slowing down of the water pump is the best advantage , power gain is not that great. The alt may last longer as well.

 

you also go to worry about fuel delivery ie the fuel pump and the voltage it gets and how that is affected with an increase in RPM