Jeez it's been a while since I've posted...
I was hoping some folks could give advice & real world experiences with LT4 conversions on A4 cars..Specifically,What's the optimum gear for the best MPH thru the traps?
I have a ZZ430 clone in my G-body & it has similar HP/torque to an LT4 Heads/Hotcam/intake package.
I'm running a 700R4/3.42 & only turning a little over 4K RPM at the end of the 1/4.This seems low.



EDIT:I just noticed I posted in "Advanced Tech".
I just tried the 'search' button looking for an answer,but the only thing that came up didn't answer the question.So I hit 'new post'.
This is where the post ended up..I apologise...

 

I would think that getting the converter matched well to the combination would be job one. In my book anyway. Having not built a combo like that I'd think that something in the 2500-2800 range would be about right for a strong street setup. Probably 3500+ or so for a more track-oriented setup. You want to stall at a point the motor is reasonably "on the cam" and making good torque.

RPMs through the traps I'm assuming you're going through in 3rd. For a street car don't be too concerned about the RPM you're going through the traps. Doesn't make as much difference as you would think.

Gear to come out of the hole like a raped ape. Throw everything at those rear tires you can possibly scrape the traction together to contain and lay to the pavement. 3.73 with a 700R-4 is probably a good starting point. I'm trying 4.10s with a similar combo using a mild carbureted 350 this year. We'll see if I can keep the tires planted. The 700R-4 has a very steep 3.08 first gear (vs. 2.50-2.60 for most factory transmissions) so you don't need as much rear gear to launch it hard as some transmisions (assuming the tranny doesn't go ka-boom).

 

You should get more responses on "LT1 Tech"...... moving post there.

 

Try 3:73.1's and a 2400 Rpm Stall. Rpm is low should be around 6k mine is going through end of quarter at Epping, hard to tell tranny is slipping again! Trap speed around 103 before the hired help came along! (powerdyne unit)
LT4 makes its power from idle to redline acccording to Izzo @ LS1speed.com He recommended that setup.
How you doing my Brother? Coorslight machine back on the road yet?