trans baseline setup help

Just swapped to a B&J 3 spd and wondering what some thoughts are on a setup starting point to work around. what stall speed? what gear ratios in trans? We are running 1/4 mile have a 4.30 gear also have a 4.56 if i need to change,34.5 tire, 526 new century w/1471 roots, figure on 2000hp 2700lb door car, our thoughts were starting with a high stall 6000 +, and maybe a 1.35/1.40 ratio right now i have 4 gear sets to choose from 1.35,1.40,1.45,1.55 any thoughts would be great
Thanks

 

Do you plan on leaving with an air throttle or a two step? What kind of tracks do you run on and what is your end goal? The blown door cars that I have been around run some where between a 1.98-2.10 and a 4.30 rear gear. This is with a clutch, not a converter. Do you have the ability to pull timing if the car is too aggressive at the hit? I would pick a converter manufacturer, there are quite a few with some fast stuff out there, tell them what you have and what you are trying to accomplish. They will be able to point you in the right direction and help you make stall changes down the road to fine tune your combo.

 

launching using a 2 step, we have the power grid so we can pull timing, Tracks are pretty good.

 

c mon guys give some help,what is the number that is a good starting point for a convertor car??how is that number calculated trans x rear x tire circumference??if the ratio is on the low side what tuning help should you use,what tire speed numbers should you try for...

 

I'd start with the 4.56 in the rear and run the trans as a two speed with the 55%, 10.5 inch converter from one of the good manufacturer's coan, ptc chance etc. launch at 4000 start with 10 out for 1 second and ramp back in, all in at 3 seconds, wheel speed numbers are not where it's at in my opinion I look at the pattern the slick leaves on the launch and out to 120 ft or so. If you want to run a three speed I wouldn't go above 1.70 for a first gear ratio.

 

baseline

We ran a roots big chief chevy at 2900lbs with a 4.56 and 1.80 low 3 spd with an old school chance converter.I can't remember the graph that was fastest but i started with half the timing dumped and a simple 2.5 second ramp.
This was an eighth mile deal that went 1.03 4.19 173mph. I think around 8600rpm at the stripe but keep in mind the NXS will lockup a lot better.

The car was never "up on the tire" and had low wheelspeed but it worked on the worst tracks in the country.
I never pushed wheelspeed back then and thought 1.03 was good enough for 2900lbs.
IMO start soft and keep adding timing to see how it responds. I mostly watch the .5 second increment. If you are around 3000rpm there the car should be getting happy.

one thing to keep in mind...you can't really weak shake a converter car but if the timing starts coming in and the tire is not happy it will shake, spin and fail.
I had an easy time with our roots but our screw car is so mean at 1.5 seconds that you kinda have to commit on the hit and be a little aggressive or you will suffer all the way down.Once the tire is happy early you can throw outrageous hp to it.