Launching off a transbrake bog?

May I ask why some guys like to run a transbrake up against a rev limiter on the launch? The converter will keep the engine from free revving. So If I have a 5k stall converter, nail the throttle to the floor, on the brake, it shouldn't rev higher than 5k rpm, right?. I don't run a transbrake, just trying to understand.

Originally Posted by extranjero

May I ask why some guys like to run a transbrake up against a rev limiter on the launch? The converter will keep the engine from free revving. So If I have a 5k stall converter, nail the throttle to the floor, on the brake, it shouldn't rev higher than 5k rpm, right?. I don't run a transbrake, just trying to understand.

Not all tracks will take a full converter launch... Some converter companies will tell you to leave a little in the converter .i.e Rev Limiter. Some will tell you to floor it.

We normally floor it, but there has been times on a 10" car that we need to lower the rpms to get the car to sixty foot.

Originally Posted by extranjero

May I ask why some guys like to run a transbrake up against a rev limiter on the launch? The converter will keep the engine from free revving. So If I have a 5k stall converter, nail the throttle to the floor, on the brake, it shouldn't rev higher than 5k rpm, right?. I don't run a transbrake, just trying to understand.

Yep thats the basics of it. A converter that will fash at say 3200 will stall at 4000 or even higher on a t-brake.

If you set you 2-stage at say 3k and your converter will go to 4.5k, what happens when you launch it? Meaning does it fully engage at 3k or does it flash from 3k to 4.5k. I have played with mine a little and found that it works best at 4.5k but I do not have any traction issues.

Originally Posted by 347LX

If you set you 2-stage at say 3k and your converter will go to 4.5k, what happens when you launch it? Meaning does it fully engage at 3k or does it flash from 3k to 4.5k. I have played with mine a little and found that it works best at 4.5k but I do not have any traction issues.

At a lower rpm the car will leave but the reaction time for the car to leave will be slow. Most racers use a transbrake to improve thier reaction times and leave off a floored car. You'll be more consistent on the converter.
Are you using N2O, The reason I ask is the converter stall is aweful low for a 347 (short stroke) and the weight of your car. We have a 3290lb car and use a 5500 converter. Just curious.

Jeff

It also depends on the converter and driveline configuration. Some converters like to flash and will 60' better when hit from a lower RPM. Some don't. YMMV, this is why you rack up 12 passes on a T-N-T night and go home with more questions than answers.