ATI Damper - 25% U/D
Melting Slicks
Joined: Nov 2007
Posts: 2,780
Likes: 934
From: Indianapolis IN
I find this interesting because I spoke to one of their technical guys a few years ago and he told me there was an internal discussion at ATI about whether or not to produce a 25% under drive. The primary issue was it wouldn't dampen the crankshaft harmonics to a level they felt was required, but it was needed to compete with other companies. Looks like the bean counters may have won out on this one.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
My engine builder had this very conversation with ATI (at the PRI show last month as a matter of fact), and the 25% is OK on stock("ish") motors, but ATI does not really recommend the 25% underdrive for larger cubed or stroker motors. Not enough mass to properly dampen the crank harmonics as stated above. So we went with the 10% for my LS2 stroker.
Thread Starter
Racer
Joined: Feb 2005
Posts: 280
Likes: 2
From: Houston TX
Well the dealership has been trying to figure out the right belt length all afternoon, now they're keeping it until tomorrow because of it. ATI was no help at all (again) - they said use a string to measure it. That makes me nervous.. I guess that means they never actually tested one of these on a Corvette? How can they not know the correct belt length? I certainly expected better customer support than this. Guess now I'll just have to hope it works like it's supposed to and I don't end up with engine pieces flying everywhere. 
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Thread Starter
Racer
Joined: Feb 2005
Posts: 280
Likes: 2
From: Houston TX
I looked around at other manufacturers 25% underdrive pulleys and they all seemed to recommend a 77.5" belt, which is what I told the dealership to try. Apparently the parts department doesn't know how to find one that length. I did find something for the A/C belt too but forgot what it was exaclty, something in the 40's though.
Thread Starter
Racer
Joined: Feb 2005
Posts: 280
Likes: 2
From: Houston TX
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