LT4 pulleys
Thread Starter
Melting Slicks
Joined: Dec 2001
Posts: 2,437
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From: Gainesville Fl
LT4 pulleys
I know there is not a set of underdrive pulleys for the LT4 engine but can someone please explain to me what exactly the ATI pulley for the LT4 is that some people are using? ( i think it is a damper 10%?) maybe i am way off. please help me understand this and how it would be beneficial
Large Impressive Member
Joined: Jul 2003
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
The underdrive pulleys are said to be not much of a gain on the LTx engines. The only place I can see where they'd be of a big benefit would be for extended high RPM use, mainly to keep from over-speeding the P/S pump. I use the ATI Super Damper, which is if I remember correctly is roughly 3/8" smaller that the stock LT1 damper. They have a couple of others that are substantially larger but I wouldn't recommend them at all. And of course the big parts houses only carry the large ones. Jegs and Summit wouldn't drop ship the one I wanted and so I was looking at a 2 to 3 week wait. But Doug Herbert Performance was willing to and I had it in a few days. Be forewarned, they are a royal PITA to install with the engine in the car. This is due to the center hub being much longer than the stock one as it attaches to the very front of the damper instead of being recessed like the factory set-up. The next time I have the engine out of my car, I'm going to modify the boxed crossmember in front of the engine to be removable, for this and other reasons. 
Thread Starter
Melting Slicks
Joined: Dec 2001
Posts: 2,437
Likes: 1
From: Gainesville Fl
what benefit does the super damper give you? any drawbacks? does it free up hp? i am still nore sure how this differs from regular pulleys. sorry to be so naive
The underdrive pulleys are said to be not much of a gain on the LTx engines. The only place I can see where they'd be of a big benefit would be for extended high RPM use, mainly to keep from over-speeding the P/S pump. I use the ATI Super Damper, which is if I remember correctly is roughly 3/8" smaller that the stock LT1 damper. They have a couple of others that are substantially larger but I wouldn't recommend them at all. And of course the big parts houses only carry the large ones. Jegs and Summit wouldn't drop ship the one I wanted and so I was looking at a 2 to 3 week wait. But Doug Herbert Performance was willing to and I had it in a few days. Be forewarned, they are a royal PITA to install with the engine in the car. This is due to the center hub being much longer than the stock one as it attaches to the very front of the damper instead of being recessed like the factory set-up. The next time I have the engine out of my car, I'm going to modify the boxed crossmember in front of the engine to be removable, for this and other reasons.
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
The only two drawbacks are the aforementioned installation and the price. I paid around $400 for mine, shipping and all. If bought directly from ATI it's over $500! If needed let me know and I'll get the part number.
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
I know there is not a set of underdrive pulleys for the LT4 engine but can someone please explain to me what exactly the ATI pulley for the LT4 is that some people are using? ( i think it is a damper 10%?) maybe i am way off. please help me understand this and how it would be beneficial
First the damper itself is much lighter (aluminum vs steel)
Second everything it drives will turn 10% slower....I rev my engine to 6700 vs OEM 6300, plus with 4.10's I am going 18% faster at cruise, plus my idle is at least 10% higher than stock
So it works for me....
A bear to install..
