March vs. ASP Pulley
The ASP is just fine for a typical car. High HP engines should use the ATI. SFI just means it meets the safety specifications reuired for sanctioned racing events (NHRA, IHRA, etc.) 
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Originally Posted by Reckless
I would steer away from the March. It was the pulley used on the 1150hp engine my friend has. To make it short, the timing chain ended up getting bound up due to bad harmonics. Not saying it isn't a good pulley, but it was removed, changed the timing chain, and used an ATI instead. I believe the ATI is prolly the best bet, but ASP is good also for less $$$.
Come on guys, let's get real, can anyone report a March "failing" at 600rwhp?
March is SFI approved and by being so it is tested up to 10,000 rpm rotor (not an engine), then inspected for failures.
Harmonics have to be controled at both ends of an engine (dampener and Flywheel) and for added insurance at the driveshaft.
As for ASP not having any problems, I beg to differ. They did have KR issues and many posted here. A second GEN pulley was revised.
Originally Posted by NASTYLS1
I know the march pully weighs 11 pounds compared to 10.5 for the stock pully.
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This makes me reconsider about the March. I have it in my Thunder shopping cart as I write. I hope something more posetive is said. I don't really care if it weighs the same as stock as long as the weight is distributed better to improve the rotational inertia. This, along with its smaller size can impove performance and shouldn't add stress to the crank.
If your friend has a 1150 Horsepower motor then he should have been running the ATI anyway. Not too many LS1's with that kind of horsepower running around. Here is a dyno proven result for you. I had the first Generation ASP that was not SFI approved and the underdrive ALT pulley as well. With Bolt ons minus headers I picked up 8 RWHP. I switched to the March Pulley with the overdrive ALT pulley and gained 1 horsepower over my ASP setup. Keep in mind that I most likely lost power by going from an underdrive ALT pulley to an overdrive. Just my .02 The car does feel smoother with the March. One last thing, I threw 2 belts in 4 months with the ASP pulley. 1 month with the March and things look okay so far.
