But thats in the 1/8 not sure about the 1/4
Drive or 3rd for 1/4 mile?
Thread Starter
Intermediate
Joined: Mar 2008
Posts: 45
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From: Eldridge Iowa
Drive or 3rd for 1/4 mile?
Hello,
What is the the best gear selection, auto, for the 1/4 mile? The car is a 97 with LS6 ported heads, cam 238/640, LS6 intake, LT headers, built tranny with 3200 Yank, 3.15 gear, and some other little stuff. The previous owner ran a 117 in the quarter with the car in "drive". I would think it would do better in "3rd" considering the rear gear. Any thoughts?
Thanks, Dave
What is the the best gear selection, auto, for the 1/4 mile? The car is a 97 with LS6 ported heads, cam 238/640, LS6 intake, LT headers, built tranny with 3200 Yank, 3.15 gear, and some other little stuff. The previous owner ran a 117 in the quarter with the car in "drive". I would think it would do better in "3rd" considering the rear gear. Any thoughts?
Thanks, Dave
Last edited by kellyd; Apr 18, 2008 at 11:13 PM.
Race Director
Joined: Jul 2007
Posts: 10,961
Likes: 2,643
From: Texas Hill Country
Doesn't matter. If the pedal's to the metal then the ECU will make the trans do what's necessary. The rear gear doesn't change with the shifter position. The only time it's necessary to shift an automatic is when it has a manual valve body. Your's does not.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Generally the PCM will shift the A4 WOT around 5600-5700rpm. With the selector in 3rd it would shift at 5900.
Race Director
Joined: Jul 2007
Posts: 10,961
Likes: 2,643
From: Texas Hill Country
for certain years C5 (and I don't have the specifics anymore) it was reported that with the selector on "3"... the WOT shifts would happen 150 to 200rpm higher - than when in "D"
Generally the PCM will shift the A4 WOT around 5600-5700rpm. With the selector in 3rd it would shift at 5900.
Generally the PCM will shift the A4 WOT around 5600-5700rpm. With the selector in 3rd it would shift at 5900.
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Race Director
Joined: Jul 2007
Posts: 10,961
Likes: 2,643
From: Texas Hill Country
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
I'm usually the one that asks this !!! 
Back before the PC based tuning programs, it was "general knowledge". I don't know if ever later proven or not. My personal experience is that it really did shift at a higher RPM; but at the track there's too many things to be aware of than to keep my eyes glued to the tach; so it may have been wishful thinking on my part.
when running my 3.42 gears -unprogrammed- I could occasionally hit the rev limiter with WOT runs in "3"... but it never happened in "D"
Using my Predator, I've changed all the WOT shift paramaters;
so I have no way these-days to go back and try to verify it.
Back before the PC based tuning programs, it was "general knowledge". I don't know if ever later proven or not. My personal experience is that it really did shift at a higher RPM; but at the track there's too many things to be aware of than to keep my eyes glued to the tach; so it may have been wishful thinking on my part.
when running my 3.42 gears -unprogrammed- I could occasionally hit the rev limiter with WOT runs in "3"... but it never happened in "D"
Using my Predator, I've changed all the WOT shift paramaters;
so I have no way these-days to go back and try to verify it.
Drifting
Joined: Jul 2001
Posts: 1,312
Likes: 2
From: Lake Havasu City AZ
I was told by a "known" trans guy that line pressure is higher in "3rd" than when you have it in "4th" so racing in "3rd" is easier on the clutches. I hope some of the real trans rebuilders can chime in.
Mike V
Mike V
Thread Starter
Intermediate
Joined: Mar 2008
Posts: 45
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From: Eldridge Iowa
Results
Thought I'd post the results. Sorry for the delay, things got in the way. Anyway, these times are from May 9, 2008. I have not had the car back to the track. I should mention that I had a new set of street tires on back, less than 50 miles, and they were very slippery. All runs were made by bringing the rs up to around 1200-1500, letting off the brake and then rolling into the throttle. I still had to pedal it some to keep it straight.
Best of 3 runs in D
60 1.94
1/8 8.28
mph 89.74
1000 10.66
1/4 12.66
mph 112.41
Last run, I put it in 3rd
60 1.97
1/8 7.96
mph 92.20
1000 10.29
1/4 12.26
mph 114.00
I don't recall what it shifted at when I had it in 3rd, but I know it D it shifts right around 6,000 at wot.
Thanks for a great forum,
Dave
Best of 3 runs in D
60 1.94
1/8 8.28
mph 89.74
1000 10.66
1/4 12.66
mph 112.41
Last run, I put it in 3rd
60 1.97
1/8 7.96
mph 92.20
1000 10.29
1/4 12.26
mph 114.00
I don't recall what it shifted at when I had it in 3rd, but I know it D it shifts right around 6,000 at wot.
Thanks for a great forum,
Dave