Hennessey 4sp auto trans

[slapphappy]

I'm wondering what transmission is used in the Hennessey 4 speed auto upgrade, and if it will take drag racing with a 700-900 HP motor.

[John Hennessey]

Its hard to say, we dont have any test time at the dragstrip on the 4speed auto yet. But I can tell you that it will live a heck of a lot longer than a 6speed with big power. Ask the guys that keep breaking their 6speeds.

Our 2speed powerglide package has been bullet proof and has over 30 passes in the mid to low 9's plus an 8.93 pass and it has never had a problem.

[BigCarrot]

There you have it.

[FlyBryViper]

I know it depends on gearing, tire size, stall speed, etc. but would the 4 speed auto box even get into 4th gear in the quarter?

[mxblue23]

Originally Posted by FlyBryViper

I know it depends on gearing, tire size, stall speed, etc. but would the 4 speed auto box even get into 4th gear in the quarter?

In most autos 4th is a .67-.72 OD, so effectively a bit taller gear than 5th on the T-56. If your hitting 5th then you will use 4th with the auto.

[FlyBryViper]

So the majority of Vipers would never get to the 4th gear of this auto box, in the 1/4 mile.

[RedGTS]

I'm also interested to hear how that tranny would work with a centrifugal blower and 850+ rwhp for street and track use. Wouldn't you have to use a really high stall speed to launch effectively, and wouldn't that be a PITA on the street?

[RedGTS]

This is very interesting too if it's all the manufacturer claims it is:

http://vca2.viperclub.org/forums/showfla...;o=&fpart=1

[FlyBryViper]

I think it would be great if we could shift our Vipers like the WRC cars, electric or manual.