thumpinc5

I have a 2001 Coupe that the motor is being for right now. A realistic estimate with the build is 500HP at the flexplate and the potential to spray another 250 on top of that. 4L60E transmission with a 3200 stall. This car get's driven ALOT. How much quarter mile gain could I really expect, going from 3.15s to 3.73s?

LS1LT1

As long as there's traction (that's key) the gains could be as much as a full two tenths+ reduction in 1/4 mile ET, no less than one full tenth though. Some trap speed gains as well.

thumpinc5

Will be running drag radials on 17"x11" ZR1 wheels. Cecil County usually has pretty good hook.

Frank

billet racing

One - Two tenths does not seem like much for the money. What about going from 2.56 to 3.15's?

Since you already answered, it's not really thread jacking, but just expanding the knowledge.

Jerry

LS1LT1

That's for a 2006+ C6 A6 (6L80) I assume?
The end results/gains will likely be about the same, maybe not even as much as it would be with going from 3.15s to 3.73s in the earlier A4 (4L60/4L65) cars. The A6 transmission has some pretty steep (numerically high) gearing inside of it and this really helps it get out of the hole nicely, especially with a well matched high stall converter.
Quite a few of us have a lot of success with the stock 2.56 gears still in the car, a few of us have even gotten well into the 10s on 2.56s with just bolt ons.

93 ragtop

My concern would be with the 4l60 in drive what rpms are you going to be turning at the end of the qtr. assuming it is 750rwhp and using a 3.73 gear?

thumpinc5

4L60E has a .070 overdrive/4th gear. A 3-4 shift should keep RPMs under the limit.
Frank

LS1LT1

True, but most will recommend against letting it go into overdrive under wide open throttle like that, the 4L60/4L65 (most transmissions actually) isn't known for cooperating with that hard 3-4 shift when there's a lot of power behind it.
I would sooner go with a taller tire (which can also offer further traction benefits as well) in order to allow it to cross the line in 3rd.

93 ragtop

If it were me, I would run the car with the gears you have now. See what you trap at, then use one of the online calculators to determine gear ratio. FWIW I have let mine shift into 4th and it hurts the et.

thumpinc5

I own a transmission shop that specializes in racing 4L60Es. We have a customer running 9.8 with a 4200# Impala SS with one of our 4L60Es. He leaves in manual 3rd and makes a manual 3-4 upshift. The car traps 137, and pulls 1.3 60 ft. times. 4.10s with 28" tires.
He's making right around 750 FPHP, which is where this thing would be if I spray all of it. I'm almost 1000# lighter though. The real goal for the car is to run a mid 10 on a conservative shot (150ish). I'm just not sure the 3.15s will be able to put me there.

Frank

thumpinc5

Makes sense. The gears are already in it. I may just go ahead and make a few passes to see how close I am to my goal. This thing is going to see quite a bit of highway miles too. It is being built primarilly as a show car... We just want a really fast show car

Frank

thumpinc5

Thanks for the help guys. I'm still from the old school where everything had to have 4.10s or 4.58s to be fast...LOL

Frank

93 ragtop

what are you looking at for a redline? What size tires are you going to be running? What is the approximate weight of the car and you in it?

thumpinc5

Cam makes power to 7200. 26" tall drag radial on 11"x17" wheels, Full weight coupe with a 200# driver.

Frank

93 ragtop

ok, just for fun using this calculator http://quartermilecalc.com/ assuming 750 fwhp, and 3200 lb weight, you would get 10.68et and 139mph.
Then using this calculator http://richmondgear.com/101032.html you would go through the traps at 6748rpm assuming 140mph in drive. But my experience on these calculators are they are a few hundred rpm low and I believe it is due to slippage in an automatic. So long story short, you would be real close with the 3.73. Maybe could use even a little more gear, but again, I would run it and see what it does first with the 315 gear.
Good luck and I look forward to seeing your results!!

LS1LT1

I think you'll be surprised at just where those 3.15s can get you with that kind of power/torque.
I would try it.

I went 10.7/10.8s at over 127+mph with only 2.56 gears and under 400rwhp, but that was with a 6L80 (A6 with that steep 1st gear) in my bolt ons only C6 LS2.

thumpinc5

Thanks for all the input. I really appreciate it.

Frank

thumpinc5

I see you race at E-Town and Atco. My home track is Cecil County, but I've ran at both of them too. Back in 2002 GM High Tech did a "Bolt On" LT1 shootout at E-Town. They rented the track for us for the day. They invited the 12 fastest cars from around the country, so we had the whole track to ourselves all day. I ran 13.17 in the heat with a '93 Z28 that had never had an engine mod and still had exhaust manifolds. The car had been 12.82 previously. Eventually went 12.05 with heads and cam. I raced our '70 Camaro at Atco a few times. Went 11.20 there with pine needles all over the top end...LOL. I've been 10.84 with it. Small block, all motor car.

Frank

LS1LT1

Nice, I'd been to a few of those E-town magazine track rentals (Muscle Mustangs/Fast Fords and a couple of GM High Tech magazine photo shoots/tests).
I also knew a few of the LT1 guys back in the day...Brian from south Jersey with the red Z28 used to run pretty good and 'PHATKOP' had a black Camaro well into the 11s I believe, fun times.

thumpinc5

Brian (ProjectZ) is a friend of mine. I built the trans for his car. He sold the car a few years ago. HE was the reason I went with the CC305 cam in mine.