i just ordered the march underdrive pulley kit, it comes with the crank and alternator pulley they are black steel pullies and claim to add 12-15 rwhp anyone ever use them? how do you change the alternator pulley? what size belt do you use? these things were suprisingly cheap at $60 for the pair compared to the ASP underdrive set @ $89 a set but aparently there on backorder and i wont see them for a month!

 

Pulleys don't add horsepower. They simply free-up power that you are already producing by replacing OEM pulleys with larger ones, which in turn slows down some accessories. In this case you are replacing your crank pulley (which slows all accessories down) and an altenator pulley which will slow in down ever more. You will want to make sure that you are charging your battery with enough juice and make sure to note if you are running hot due to the water pump being slowed down.

Also, is it just me, or is it odd that they are steel instead of billet aluminum? A great advantage to doing a pulley kit is that there is less unsprung weight on your crank.

 

i know they don't ADD power and they are available in aluminum too but its $170 MORE for that premium i doubt they really free up $170more dollars worth of power

 

There is a reason they are more expensive. Get your truck dyno'd before and after you do the pulleys. I would be surprised if they add 15 hp to your bottomline.

 

considering $60 is about a tank of gas, ill put the bigger money towards more worthwhile mods. i think im getting an M1 intake by the end of the week if all goes well