Just wondering. I had my 99 Formula M6 speedo completely buried, just wondering if a auto can do the same thing or will it run outta rpm.

 

Really no difference, since 5th in an M6 is virtually the same as 4th in an auto (.70:1 overdrive).

Buried the speedo on mine pretty easily when the car was stock, and I had nearly 700-800 rpms left. In Motor Trend, a Lingenfelter Formula 383 (minus nitrous) that was a virtual clone of my car hit 192 with an A4/3.23 combo.

 

No, that car was a 6spd if I remember, (that was my favorite article from Motor Trend, I have it put aside. The one with the Fiske's right?). And speaking of buried, I just tried last week to see how fast I could get my car before putting it away. I got to about 135, almost running outta gear. This car's been kinda dissapointing in the top end. But I know with LT's, it should get to 150.

 

I thought M6 topped out a little higher than the A4.

 

The M6 should top higher simply because it has more HP going to the wheels

Ive almost maxed my OD gear with 3:42s just food for thought. (5300rpm - 169mph)

 

My guess is that it should be very close between an M6 and a 3.23 auto. A 2.73 car will be slower by a few mph.

Jason

 

MY LT1 A4 2.73 can bury the 150mph speedo and keep on climbing. I think after our cars get over 100mph though the speedo isn't quite as accurate as it should be. Maybe it's 130mph, I dunno. I think 6spds are a few mph faster though cause of less loss through the drivetrain. Like someone else said.

 

I know that when my A4 car had 2.73s and it said 130 on the speedo, I was actually running 135.

As for top speed, I can't say for sure because 135 is as fast as I've EVER been in my car.

Theoretical top speed for an A4 2.73 LT1 with stock 5700 rpm rev limiter is going to be 248 MPH.

I would assume though that the M6 would have a higher top speed if all other things with the car were equal (rev limit, rear gear, tires, etc...), simply because the M6's 2nd OD is geared numerically lower than the A4's 4th gear...

 

You would need around 850-950 horsepower to pull OD with 2.73s at 248 mph. Maybe more.

Again, the M6 cars have minimal advantage, and none gearing-wise. NO car is gonna pull 6th with stock rear gears. I saw Doug Rippie's 550 hp ZR1 only get 180 mph or so trying to pull 6th...and he had 4.10s!

 

from what i know. lower gears usually mean better top-end. which would mean a 2.73 will be better than a 3.23.

 

Depends on the power you're pushing. No point of getting a tall gear if you're car will run out of ***** before it runs out of gear...... Don't forget that wind resistance becomes a huge factor once you start going over 100.

I think that was big thing for ZR1's. They made a lot of power on the top end but ran high 12's with 400+ HP. They screamed on the top end though. 180-185MPH factory Corvette is pretty sick. I heard they limited it to 185 don't know if that's true. Can't remember what kind of gearing they ran.

 

ive buried the 150 speedo in my a4(3.23) and it keeps pulling so i dunno but it gets to 150 fast

 

i've gotten to 130 or so with my ttops off... and after it was climbing up very slow.. did the same with the windows up, tops on, and at 130, i was still pullgin when i had to let go

 

That's just for top end acceleration in maybe the 100-120mph range. Top speed is totally different. 2.73's with a 30% overdrive is too much for an LT1 or LS1 to pull much past 150 if any. With those gears, 3rd gear would be almost as good for top speed. In a stock or bolt on car with the rev limiter bumped up, 3rd gear would be the top speed gear if you could take it to 6k or slightly beyond. I know for a fact that a 2.73 LS1 will go 158 in 3rd limited by the redline at 6k go figure.

Jason

 

Okay, so a LT1 or LS1 with say 3.42's or 3.73's will have enough gear to pull all the way to say 160 (with sufficient horsepower of course)?