Chances are good you’ve heard about torque converter dump valves in the drag racing community. Ever wonder what they are? A properly designed, tuneable dump valve system lowers the oil level in the torque converter by bypassing charge oil back to the oil pan causing cavitation within the converter. This cavitation reduces the forward thrust generated by the converter against the flex plate which helps to reduce engine thrust bearing wear, increase available stall speed, engine responsiveness and boost response/transition while staging against a transbrake in forced induction applications.
Dump valves can be activated at any point during the run where it may be beneficial. Activating the dump valve momentarily during a gear change will provide less engine rpm drop causing smoother, more linear acceleration. The dump valve can also be activated to help with power and traction management as needed. High power nitrous cars benefit by activating the dump valve after the transbrake is released to take the load off the engine, reducing the chance of detonation, it also reduces how violently the tires are shocked early in the run.
Hughes makes a nice 2 stage kit for the powerglide and 400. These are beneficial on small displacement, large turbo engines with larger a/r turbine housings and aggressive, large diameter turbine wheels.