Stall Converter Guide

A torque converter is a fluid coupling that connects your engine to the automatic transmission. Inside the converter, the impeller (connected to the engine) spins fluid that drives the turbine (connected to the transmission input shaft). The stator redirects fluid to multiply torque.

Stall speed is the RPM at which the turbine begins to rotate at the same speed as the impeller — the point where the converter "locks up" and stops multiplying torque. Below stall speed, there is significant slip between the impeller and turbine, which is what allows the engine to rev while the vehicle is stationary.

For performance builds, you want the stall speed to match your engine's torque peak. If your cam makes peak torque at 3,200 RPM, a 3,000-3,200 RPM stall converter will allow the engine to be in its power band right as the vehicle launches.