Underdrive Q
 

Hey, Quick Q. this motor i have has underdrives, but no alt. Will there be a problem running the underdrives on everything but the alt?

One last thing, this truck is going to be used as a rock crawler, should i go with an electric fan? or will the stock fan with underdrives have sufficent cooling power?

Thanks

Re: Underdrive Q
 

should be fine. an underdrive pulley on the alt. or the water pump will make that accessory turn less, thus freeing up more power. the original pulley on the alt should be a larger diameter than an underdrive alt pulley, thus the alt will turn faster. i would take a faster turning = better changing alt vs. a 1 horsepower gain with an underdrive alt pulley cuz thats about the only increase u'd see.

the stock fan should be fine. i would use that along with a good water temp gauge. if it runs hot there are many solutions.

Re: Underdrive Q
 

#1: You should be fine, lots of folks do "partial underdrive" you just wont free up quite as much hp (nominal difference)

#2: Honestly, I dont know much about what crawlers need to be able to do. If I was in doubt, I would err on the side of caution. Too much cooling?Good. Not enough? Bad. :D

J

Re: Underdrive Q
 

well basically it will be at an idle almost for a long period of time, just dont want to boil over crawling up a trail. might as well install the electric fan just to be safe.

i didnt choose to put these on the truck for more power, but they came on the motor.

Re: Underdrive Q
 

why not leave the stock belt driven fan on and install a pusher electric fan in front of the radiator? run the electric fan off a thermostat or put your own toggle switch for total control, or both!

Re: Underdrive Q
 

actually, that is a good idea. i may just have to do this. ive got a tarus fan, but its a puller fan, so i dont think i can reverse the current flow and run it as a pusher, or can i?

Re: Underdrive Q
 

Just use the taurus fan. It'll cool just as well as the stocker. Another issue is can you get a shroud to fit a stock type fan on a 302 in a bronco II? I'd just do the electric.