ATI Super Damper UD Versions
Thread Starter
Safety Car
Joined: Nov 2007
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From: Bethesda MD
ATI Super Damper UD Versions
I was looking through the ATI catalog and saw 3 options listed for the Y-body LS1 / LS2 / LS3 / LS6 (excluding dry sump) that were aluminum shell with steel hub with A/C support.
P/N # 917266 - 7.53" OD with no underdrive
P/N # 917278 - 6.78" OD with 10% underdrive
P/N # 918848 - 5.50" OD with 25% accessory underdrive and 10% A/C underdrive.
In reviewing threads on underdrive pulleys, I've noticed that the straight 10% underdrive (P/N 917278) seems to be the damper of choice. For a cammed LS3 with a higher idle speed, is there reason not to use the 25%/10% damper? On my LS1, I ran the 25% ASP pulleys with no issues.
P/N # 917266 - 7.53" OD with no underdrive
P/N # 917278 - 6.78" OD with 10% underdrive
P/N # 918848 - 5.50" OD with 25% accessory underdrive and 10% A/C underdrive.
In reviewing threads on underdrive pulleys, I've noticed that the straight 10% underdrive (P/N 917278) seems to be the damper of choice. For a cammed LS3 with a higher idle speed, is there reason not to use the 25%/10% damper? On my LS1, I ran the 25% ASP pulleys with no issues.
Last edited by Ragtop 99; Jan 4, 2011 at 07:43 PM.
Burning Brakes
Joined: May 2009
Posts: 1,178
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From: Austin Texas
VERY GOOD QUESTION!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!
I just ordered an ATI underdrive pulley for my vette install, but didn't notice till after the order was placed that ATI actually offered 2 LS3 versions!
EVERY sponsor on here only list the 10% accessory under drive version and that is the one I initially ordered. After realizing ATI offers a 25% accessory /10% AC under drive pulley.........I reordered that one, but there was a mix up during the install and the larger 10% accessory under drive pulley was used/installed.
WHY IS IT, MOST OF THE VENDORS ONLY OFFER THE P/N # 917278 - 6.78" OD with 10% underdrive........like the one that ended up being installed on my vette?
I just ordered an ATI underdrive pulley for my vette install, but didn't notice till after the order was placed that ATI actually offered 2 LS3 versions!
EVERY sponsor on here only list the 10% accessory under drive version and that is the one I initially ordered. After realizing ATI offers a 25% accessory /10% AC under drive pulley.........I reordered that one, but there was a mix up during the install and the larger 10% accessory under drive pulley was used/installed.
WHY IS IT, MOST OF THE VENDORS ONLY OFFER THE P/N # 917278 - 6.78" OD with 10% underdrive........like the one that ended up being installed on my vette?
Last edited by C6-LS2-MN6; Jan 10, 2011 at 10:36 PM.
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
I was looking through the ATI catalog and saw 3 options listed for the Y-body LS1 / LS2 / LS3 / LS6 (excluding dry sump) that were aluminum shell with steel hub with A/C support.
P/N # 917266 - 7.53" OD with no underdrive
P/N # 917278 - 6.78" OD with 10% underdrive
P/N # 918848 - 5.50" OD with 25% accessory underdrive and 10% A/C underdrive.
P/N # 917266 - 7.53" OD with no underdrive
P/N # 917278 - 6.78" OD with 10% underdrive
P/N # 918848 - 5.50" OD with 25% accessory underdrive and 10% A/C underdrive.
Thread Starter
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
I called ATI and spoke with a member of their tech staff about the performance difference for the LS3.
Under 500 RWHP, the 25%/10% pulley is fine. As output goes over 500 RWHP, they start to favor the larger diameter of the 10%/10%. It wasn't a bright line test although he said and when you start approaching 600 RWHP, they would only use the 10%/10%. At 500 RWHP, the 10%/10% offers the ability to grow if more mods might be in the future.
Under 500 RWHP, the 25%/10% pulley is fine. As output goes over 500 RWHP, they start to favor the larger diameter of the 10%/10%. It wasn't a bright line test although he said and when you start approaching 600 RWHP, they would only use the 10%/10%. At 500 RWHP, the 10%/10% offers the ability to grow if more mods might be in the future.
Thread Starter
Safety Car
Joined: Nov 2007
Posts: 4,537
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From: Bethesda MD
Both the 10% and 25% are available without A/C. The steel hub models are:
10% = P/N # 917279
25% = P/N # 918847.
Last edited by Ragtop 99; Jan 5, 2011 at 03:05 PM. Reason: Added P/N
Team Owner
Joined: Feb 2001
Posts: 27,254
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From: Short Hills, NJ
Same here...but I was under the impression that it simply meant that they one could go with just the crank pulley alone and not underdrive the A/C compressor if they chose, not that it was for those that did away with their A/C. Meaning that they send you one pulley instead of two but your A/C still works (off of it's factory/stock pulley). But I might be misinterpreting that part.
Thread Starter
Safety Car
Joined: Nov 2007
Posts: 4,537
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From: Bethesda MD
My understanding is the "No A/C" option is for those who deleted the A/C from their car.
I don't have a picture of the stock pulley handy, but I don't see how that would work. The A/C has its own separate belt and is not in the same plane with the accessories.
I don't have a picture of the stock pulley handy, but I don't see how that would work. The A/C has its own separate belt and is not in the same plane with the accessories.
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Team Owner
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From: Short Hills, NJ
Burning Brakes
Joined: May 2009
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From: Austin Texas
I've owned SLP/Power Bond/ASP/and now a ATI.......For the longest time I never wanted to try the ATI because of the high price, but the build quality of the ATI is just amazing compared to the others (all CNC'ed) and it's also internally dampened by a rubber ring inside, unlike the others!
The others resemble stamped sheet metal and have been associated with timing chain breaks, but no proven data to back it up from what I've read...so who knows.
The first picture just has dust on the pulley from the card board shipping box.
The others resemble stamped sheet metal and have been associated with timing chain breaks, but no proven data to back it up from what I've read...so who knows.
The first picture just has dust on the pulley from the card board shipping box.
Last edited by C6-LS2-MN6; Jan 9, 2011 at 02:30 PM.
Thread Starter
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
I've owned SLP/Power Bond/ASP/and now a ATI.......For the longest time I never wanted to try the ATI because of the high price, but the build quality of the ATI is just amazing compared to the others (all CNC'ed) and it's also internally dampened by a rubber ring inside, unlike the others!
The others resemble stamped sheet metal and have been associated with timing chain breaks, but no proven data to back it up from what I've read...so who knows.
The others resemble stamped sheet metal and have been associated with timing chain breaks, but no proven data to back it up from what I've read...so who knows.
My cam is smaller, so I decided to go with just the 10%/10% since I may end up with 750 rpm idle. If I knew I were going to use an 800+ rpm idle, I would have gone with the 25%/10%.
Safety Car
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St. Jude Donor '11
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The engine runs smoother. It's most notable at idle.
Look at the design of the factory piece and the design of the ATI part. The weight is there for a reason.
The factory stacks tolerance and as such you will get a certain amount of vibration. The ATI is a better tuning fork.
Look at the design of the factory piece and the design of the ATI part. The weight is there for a reason.
The factory stacks tolerance and as such you will get a certain amount of vibration. The ATI is a better tuning fork.
Drifting
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From: Oshawa Ontario
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