mdhmi

Let's say TT car A with an M6 has 700 BHP which is roughly 600 rwhp (15% drivetrain loss) and TT car B with an auto has 700 BHP which nets 525 rwhp (%25 drivetrain loss).

Which car would be faster in the 1/4 mile (I'm guessing the auto) and which car would *feel* faster on the expressway doing 50-140 MPH pulls?

Thanks,

Mark

Mopar Jimmy

I'm no expert but my $ would be on the auto car in the 1/4 mile (most variables being equal) and I believe the stick car would be faster on the highway!! Also, the rule of thumb i have seen around these parts the last 5 years has normally accepted drivetrain loss on a A4 at 20% and not 25%, and assuming this to be accurate at 20% loss, the A4 car would be putting down 560 horsepower to the wheels vs the 595rwhp on the manual tranny with 15% drivetrain loss!!

Again, most know however, that the 1/4 mile outcome would be more dependant on the driver and if you had traction and a REAL PRO slamming the gears on the stick car vs. a regular JOE in his A4 car, the manual vette with the professinal drag racer would be your winner!!

RoadRebel

The auto in the 1/4, specially the way you drive the M6.
The stick on a 4th freway pull will feel faster than the auto.
But hey, atleast you make it to the track .

Phil

Emuffinman1

Blown ECS Z06 is right on with his analysis.

Paul

NICK YOSKIN

DOUG @ ECS

another thing to think about is with the six speed at the track it is also easier to have traction issues due to the "unloading" of the suspension between shifts compared to an auto.

StreetRacingGuy

you guys are forgetting an important factor in your hp analysis. The torque converte size, efficiency and whether or not it was "locked" during the dyno pull makes a huge difference. My A4 with unlocked 4000 stall Yank Prothruster turning 315 tires on 17X11 rims will look weak on a mustang chassis dyno compared to a stick car with 275 tires on 17X9 rims on a Dynojet. THe difference realistically could be 100 hp in this situation. On the same dyno, same car, same engine (lets say 600 crank hp NA), etc with the ONLY difference being stick or auto.....the high stall/.unlocked auto car will show rwhp of about 450-465, whereas the stick car will show maybe 525-540 rwhp. Guess which one will beat the ever living **** out of the other in the 1/4 mile?

In the above situation, my car and a friends car....he dyno's 480+ rwhp, I did 430 rwhp. My car is about 5-7 mph faster than his in the 1/4, and makes a bunch more torque (547 rwtqe for me, and 460 for him). Mine is a stalled unlocked car, his is a 6 speed car.

Don't get hung up on rwhp numbers....FI 6 speed cars can make insane rwhp numbers, but a stalled/automatic car with 100 rwhp less can often run with or beat the higher hp car. I have proved this MANY MANY times around my area....for cash....on the street. It sounds neat to say I have 545, 575, 650, etc. rwhp....but it is a lot neater to say....I will race you from a dig for $500 and give you 3 cars....and be confident in the outcome with less rwhp.

Streetracingguy

RED99

I think after 500 or so HP, it's more of a traction and drivers skills than HP that wins the race ( unless it's a great deal of HP difference). If you can't hook up, then you are losing time. Autos will do better for drags over manual on a turbo motor only because you can load the motor and build boost on the line. You can't build boost by just sitting there reving the motor with a Manual Tranny. But again, if you don't have traction, then it's no gain.

0Cunningham Motorsports

well you could put a two-step on the manual turbo car.

BLOWN'NC

I ran a high juiced cobra when my A4 was stock with 3.15 gears/converter and he got the "manual/juice jump" off the start and then stopped pulling.

With my current setup with 3.73s, RPM level 5 (that doesn't lose 3-4# of boost on the 3-4 change like the stocker), and the 2800 stall, I'm always near if not in my sweet spot

TORXILA

Give us a few months and your questions will be answered...

mdhmi

If you beat me I'm just going to turn up the wick.

Mark

gymtitan

I sure do hope the A4 is faster and especially with a turbo since that is what MDMC starting installing on my car yesterday!

TORXILA

I'll watch for the parts shower....in my rear view

George

Earl H

Is spring here yet?

Jason Blue Boost

We'll have an answer later this year.

corvettebob1

Hey Mark, I thought you were going to convert to the A4 this year whats up with that?
The bad news is he's going to wax you in the 1/4 mile.
And the worse news is "If he's set up correctly with the right converter and final gear ratio you may feel faster from 50-140 mph but side by side I'd put my money on him."
BTW when I was still working at GM the accepted drivetrain loss for the A4 was 18% or less and what they lose in loss, is made up in torque mutipilication.
However the manual will always "feel" faster even if it's not.

mdhmi

I have to replace my current trans, so that's what has me thinking about the auto.

The reason I asked about the freeway SOTP difference was I was curious if I would have to turn up the boost with the A4 to feel as fast as with the M6.

Mark

corvettebob1

Thats going to be a tough one to call, my guess at your current power level you may need to turn it down to get traction.

LRD VDR

I could be very very wrong but I really don't see an A4 having a 25% loss. I could see that in a built C6 or something.

Shahram