One thing that I cant figure out is how do you tell what stall it is by phycially looking at it?? Every TC I have seen does NOT have the stall hard stamped into the bell.
Stall speed is dependent on amount of torque engine makes, the weight and gearing of vehicle as well as how converter is built. Let’s say we take the same converter and install it behind two different engines a small block (lower torque out-put) and a big block (higher torque out-put) in same car, that converter will stall at a higher speed behind the big block than the small block.
This is why you have to have all the build information of engine and drive train etc. so converter builder can estimate engine output and normal cruise rpm car will be operating on the street to come up with a compromise that is efficient on the street, and still delivers at the track. Also why a converter is not labeled as it depends what it is hooked to.
If you just pick a stall speed out of thin air, or decide your friend’s car’s stall is just the ticket for your machine chances are real good you will build an expensive turd, and will sooner or later be replacing that converter with one designed properly to match your car’s build.
Pick a stall too low, and the car will be a slug off the line, won’t like to get into the power band going up steep hills, and if you have cammed up the engine, it won’t want to sit still in traffic because idle speed is at or higher than stall speed. The other side of the coin, too high stall speed will feel like engine and transmission is connected by a big rubber band. Step on the gas in stop and go traffic, it revs up and up and then starts to go, run up a slight grade and it feels like the transmission is slipping. All this looseness, constant churning of transmission fluid in the converter when not locked up generates a lot of excess heat, wastes fuel, and destroys transmissions.