looky what came in today!
Check it:

A 25% underdrive crank pulley from ASP. Took me literally 15 minutes to install. cost $75 + $25 for the new belt. They sent me a 6 rib belt pictured here:

The belt works but had the tensioner pulley pulled almost all the way to the tightest setting. I've talked with several knowledgeable guys that said that a 6 rib belt is fine on a 7 rib pulley system so long as the tensioner can hold tight and you set the belt all the way toward the engine side. I still got a little weirded out and went to NAPA and had them find me a 7 rib belt that was 5/8" longer than the one ASP sent. It fits almost like stock and I'm going to monitor it for stetch. The NAPA P/N on that belt is 070951.
Here's a comparison pic of the old and new pulley:

performance verdict? totally worth the $100 bucks. Like stacking a hypertech tune on top of the SCT tune. Not much, but noticable and a nice cheap upgrade.
Only concern is charging issue since I have electric fans, but I'm working on that.

A 25% underdrive crank pulley from ASP. Took me literally 15 minutes to install. cost $75 + $25 for the new belt. They sent me a 6 rib belt pictured here:

The belt works but had the tensioner pulley pulled almost all the way to the tightest setting. I've talked with several knowledgeable guys that said that a 6 rib belt is fine on a 7 rib pulley system so long as the tensioner can hold tight and you set the belt all the way toward the engine side. I still got a little weirded out and went to NAPA and had them find me a 7 rib belt that was 5/8" longer than the one ASP sent. It fits almost like stock and I'm going to monitor it for stetch. The NAPA P/N on that belt is 070951.
Here's a comparison pic of the old and new pulley:

performance verdict? totally worth the $100 bucks. Like stacking a hypertech tune on top of the SCT tune. Not much, but noticable and a nice cheap upgrade.
Only concern is charging issue since I have electric fans, but I'm working on that.
What are the actual benefits to an underdrive pulley (more hp, faster acceleration, etc.) and will it affect not only the alternator, but the steering pump and A/C? What I've read doesn't exactly recommend them for a daily driver.
Last edited by Miami_Son; Jun 10, 2009 at 06:55 PM.
Aim, is it just the crank pulley? March offers crank and alternator pulley for roughly the same price? Minus the belt. I was debating this on for my 01 5.2, would like to hear some more feedback. Lastly, 15 mins? unbolt old, and bolt on new?
It underdrives ALL accessories. The A/C, PS pump, Water Pump, and Alternator will all move slower. Right now the alt is my primary concern as the cooling for the Rad and PS pump will be fine if the efans are running.
You have to be careful with alt pulleys, sometimes they sell pulleys that underdrive the alt and WP or PS pump even more.
yes it is literally remove 6 bolts and bolt on the new. 200 in/lbs. per bolt.
According to ASP, it's 6hp and 26ft/lbs torque gain.
You have to be careful with alt pulleys, sometimes they sell pulleys that underdrive the alt and WP or PS pump even more.
yes it is literally remove 6 bolts and bolt on the new. 200 in/lbs. per bolt.
According to ASP, it's 6hp and 26ft/lbs torque gain.
Last edited by aim4squirrels; Jun 11, 2009 at 10:26 AM.



