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View Full Version : Very pleased with 3.73 Auburn gear swap with 5spd..



Mike Puckett
05-22-2010, 09:43 PM
A couple of weeks ago I installed a 3.73 Auburn gear pumpkin along with 2 new halfshafts replacing my 3.55 stock pumpkin. Today I took it to Atlanta Dragway and ran 4 test & tune passes about 2 hours apart to see what it would do with the extra gear. Needless to say I was very pleased with the results. I weighed the car too, and am now at 3450 w/o me in it. It's lost about 25lbs. I also wanted to be able to do 2nd gear burnouts because I can't get the tires spinning fast enough to smoke them in 1st gear when going thru the water box and I spin off the line. That actually worked quite well as long as I kept the rpm above 3000 and I got good launches with my race tunes. Also, with the 94 5spd tranny, I don't find 1st gear too short at all. Both 2nd and 3rd gear shifts do come pretty quickly but 3rd gear winds out a loooong way.The 94 tranny sure is easier to shift than the early models I'd been using. I'm having to physically soften up my shifting to 3rd. BTW my shift light is set for 5600. Anyway, My times are below. The 1st 2 passes were with my full race tune w/32 degrees of advance. The 3rd one is w/28 degrees of advance and my 4th was my street tune w/26 degrees of advance as commanded by the tune. It does appear that it is responding to it and giving me the full advance and not pulling any out. The boost cooler ran on all 4 passes with the only difference being the timing advance set by the tune. My 2 race tunes idle at 2100 rpm for launching. I wanted to be sure it would remain consistent like it's been running and I think it has.
.........1st@1:26.........2nd@4:01............3rd@ 5:58............4th @7:00

60'.........1.837..............1.843.............. ....1.857.................1.901
1/8........8.408..............8.381................. .8.466.................8.557
1/4.......13.104............13.080................13 .206................13.334
spd.......105.02............104.75................ 103.87................103.16

My consistency is still there on runs 1 and 2. I had been running 13.3's last year with the MP2 and this year 13.2s in the cool with the S-model. I suspect that they would have faded to the 13.3s in todays heat. My 4th tune w/-8 degrees is for passing emissions and I didn't try it. Temps were in the mid to high 80s, humidity was 55-60%, and DA was about 3100'.

Mike8675309
05-22-2010, 10:17 PM
What fuel do you run at the track?
Looks like you are getting it dialed in pretty well.

Mike Puckett
05-23-2010, 12:40 AM
Sunoco 93 pump gas topped off with Chevron 93 about 5/8 of a tank. The boost cooler has the track methanol 50/50 w/ water. This particular tune has been very consistent but not that powerful. It's richer than before so hopefully it's safer and no more cracked heads or blown gaskets. The coolant temp never goes above 180. Maybe I can start winning a few more rounds now at the Summit series races if it holds up.