Hey yall I want to get into pulling sleds and I got a buddy who does it and he was talking to me about getting his Torque converter to engage while he was pullin, Im tryin to figure out why uually that doesnt engage until your cruising in 3rd or 4th gear so why do you want it in 1st or 2nd???

 

When you launch there is a lot of slip across the torque converter. This slip converts RPM into torque, hence the name torque converter.

As the engine speed increases the slip decreases, and so does the torque multiplication. At some point there isn't enough slip to make any more torque, but there is still slip, which creates heat in the torque converter. The heat is also wasted horsepower, so once you reach the point where there is no more torque multiplication you'll get more power to the ground with the torque converter locked.

The trick is knowing when that point is reached. It's a very complicated calculation. You'll probably need to try different RPMs to lock to find the ideal speed. A good starting point would be somewhere around 3000 RPM.

 

ok that clears things up thanks!! We were looking at putting in a switch to manually lock the converter when we wanted it, The wiring diagram it is ground side switched so it looks we could jus splice a switch into the circuit, would that be bad for the converter to engage when not called for?

 

It would be bad if you're at less than 1300 RPM. There isn't enough pressure at low RPM to lock without slipping.

 

ok thanks for all the help!