I've been researching the 700R4 and want to do a performance rebuild but there is one thing I don't really understand. Lockup.

I know it couples the engine to the tranny but what is the function...to reduce heat? What are the advantages of running a non lockup converter if any? Would I want to control the lockup in my car with a switch? I've seen manual lockup kits that don't require any wiring and controlled internally in the trans. I don't really understand what this means and when I should use or not use lockup. My car is not stock or a daily driver. I want to be pushing between 350 and 400 hp so how will this effect lockup? I alway hear that disableing the lockup is bad...is the only reason it's bad is the increased heat? I have a tranny cooler but I want to be safe. How will it effect gas mileage if any? Please help!

 

Lockup is done to eliminate converter slipage while cruising for improved efficeincy and therefor gas milage.

Advantages to getting rid of it are simplicity, and cost. Typically torque converters that "go bad" have a failure related to the lockup clutch rather than the converter itself. Eliminating the lockup means that the is one less thign to go wrong. Also, high stall high quality lockup converters are very expensive compared to non-lockup. A typical non-lockup can be had for around $250, but lockups are in the $320-$800 range.

Unless you are looking to do a very high stall, which wouldn't make sense given you combination, heat isn't that big of a deal. You'll need to run a trans cooler. You should be doing that anyway.