Torque converter question
Thread Starter
Safety Car
Joined: Aug 2017
Posts: 4,243
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From: North Myrtle Beach SC
Torque converter question
right now my plan for my car is keeping motor stock, adding headers and uncatted midpipe to my Borla Stinger, a Vararam, a good tune and a good converter (and cooler). I had a SS3600 in my old 99 Z28 so I am familiar with them. Thinking of something similar this time. What I’m wondering is how well the converter will like the 2.56 gears. My Z28 had 3.73’s which was just about perfect. With the A6, and running at such low rpms at say 60 mph, is that hard on the converter?
Instructor
Joined: Mar 2017
Posts: 220
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From: SAN DIEGO CALIFORNIA
It will be fine, at 60mph it wont matter because the converter will be locked, so it will drive the same. I have the ss3600 on my grandsport which has 2.73s, and i love it. Best bang for buck for drag racing.
Race Director
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From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
The 3600 is fine for both the street, the highway, and the strip.. The 3200 feels like what GM should have used as stock, if the feds weren't in charge. The 4000 is a different animal and should only be the choice of the more seriously performance inclined. Over 40K miles of 1.4x 60' seriousness for me, so far. 
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glad that Hoxxy responded, and well worth it for you to heed his advice...………….. 
Tom will always be more than willing to answer any questions you have, especially since both of them are LS3's and automatics...……..
Melting Slicks
Joined: Nov 2012
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From: SUFFIELD CONNECTICUT
The 3600 is fine for both the street, the highway, and the strip.. The 3200 feels like what GM should have used as stock, if the feds weren't in charge. The 4000 is a different animal and should only be the choice of the more seriously performance inclined. Over 40K miles of 1.4x 60' seriousness for me, so far.
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Race Director
Joined: Sep 2007
Posts: 16,557
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From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Going back to your original question about the 2.56 gear and if the converter will like it, the answer is, the converter won't care about the gear ratio. However, your transmission will like the 1/4 mile track a little better, since it won't need the 3-4 shift. That's one of the weak spots of the A6, because it's more like two 3-speeds and when it shifts from one to the other, it has two functions to complete instead of one. Crossing the stripe at the end of 3rd is almost the same as crossing at the end of 4th with a 3.42 gear. You lose almost exactly .1 ET, but everything lives a little longer, especially for a daily driver. I'm about to turn 155K miles and I'm more than 450 1/4 mile passes at the track and a lot more WOT hits through 2 shifts on the street. The OEM bone-stock (short of a bit of tuning) trans is still chugging along. I'm willing to sacrifice a tenth for longevity and better fuel mileage on long road trips.
Melting Slicks
Joined: Nov 2012
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From: SUFFIELD CONNECTICUT
Thanks
Don
Melting Slicks
Joined: Nov 2012
Posts: 3,163
Likes: 686
From: SUFFIELD CONNECTICUT
Going back to your original question about the 2.56 gear and if the converter will like it, the answer is, the converter won't care about the gear ratio. However, your transmission will like the 1/4 mile track a little better, since it won't need the 3-4 shift. That's one of the weak spots of the A6, because it's more like two 3-speeds and when it shifts from one to the other, it has two functions to complete instead of one. Crossing the stripe at the end of 3rd is almost the same as crossing at the end of 4th with a 3.42 gear. You lose almost exactly .1 ET, but everything lives a little longer, especially for a daily driver. I'm about to turn 155K miles and I'm more than 450 1/4 mile passes at the track and a lot more WOT hits through 2 shifts on the street. The OEM bone-stock (short of a bit of tuning) trans is still chugging along. I'm willing to sacrifice a tenth for longevity and better fuel mileage on long road trips.
Race Director
Joined: Sep 2007
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From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Nothing wrong with the 2.73 if you already have one, since it'll still finish the 1/4 in 3rd. But I wouldn't bother swapping from a 2.56 to the 2.73 for the small (I'd guess maybe .02-.03 second) advantage.
Melting Slicks
Joined: Nov 2012
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From: SUFFIELD CONNECTICUT
Melting Slicks
Joined: Nov 2012
Posts: 3,163
Likes: 686
From: SUFFIELD CONNECTICUT
Ok, you are correct on what the post reads .02 to .03 my mistake. I honestly think the difference to 60 mph or the 1/4 mile with the 2.73 rear gear is at least a tenth or two over a 2.56 gear car, otherwise why would that be the performance gear ratio for the Z51 automatic cars? probably to speed the car up to 60 by a tenth or two which should carry thru to the 1/4 mile ET.
Race Director
Joined: Sep 2007
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From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
I was thinking of doing just that, swapping a 2.73 in place of a 2.56. 2 or 3 tenths is a big difference in the 1/4 mile with no other changes. Would a 3200 stall converter give me more bang for the buck with the 2.56 gear versus a 2.73 gear with the stock converter regarding 1/4 mile et with no more than 460 crank horse ? torque management tuned out and trans tuned to automatically shift each gear at 6500 rpm wot. I will be optimizing a 1LT with dual mode exhaust ,2.56 rear, for 1/4mile fun and a daily driver.
Ok, you are correct on what the post reads .02 to .03 my mistake. I honestly think the difference to 60 mph or the 1/4 mile with the 2.73 rear gear is at least a tenth or two over a 2.56 gear car, otherwise why would that be the performance gear ratio for the Z51 automatic cars? probably to speed the car up to 60 by a tenth or two which should carry thru to the 1/4 mile ET.
A higher stall converter is probably the biggest bang for the buck for any A6. I dropped nearly 2 tenths (.20) off my 60' when going from the stock converter to a 3200 with no other changes. Subfloor swapped from a 2.56 gear to a 3.42 and gained exactly .10, so a swap from a 2.56 to a 2.73 is almost negligible It's why I said .02 -.03..
Melting Slicks
Joined: Nov 2012
Posts: 3,163
Likes: 686
From: SUFFIELD CONNECTICUT
The 2.73 gear gives a slight edge for autocross, where a higher average rpm over the course works better. Although the 2.73 was a stand-alone option, using it in the Z51 option fit well with the stickier tires for autocross events.
A higher stall converter is probably the biggest bang for the buck for any A6. I dropped nearly 2 tenths (.20) off my 60' when going from the stock converter to a 3200 with no other changes. Subfloor swapped from a 2.56 gear to a 3.42 and gained exactly .10, so a swap from a 2.56 to a 2.73 is almost negligible It's why I said .02 -.03..
A higher stall converter is probably the biggest bang for the buck for any A6. I dropped nearly 2 tenths (.20) off my 60' when going from the stock converter to a 3200 with no other changes. Subfloor swapped from a 2.56 gear to a 3.42 and gained exactly .10, so a swap from a 2.56 to a 2.73 is almost negligible It's why I said .02 -.03..
Thank you for all the great info you guys, it all helps.
