What is stall speed and how to pick the right stall? Torque converter stall is the RPM speed at which the converter will hold the engine speed and allow no further RPM gain. Stall speed is always determined by engine peak torque. Where a mild small block would produce 2400 stall, the same converter in a built big block could produce 3000 or more stall. Correct converter stall can best be determined on vehicles with a trans brake as testing stall only with foot brake applied the engine often overpowers the brakes causing wheel spin. This RPM is not actual stall, but will give you a general idea of where your converter is set. Flash stall is achieved by wide-open throttle starts from a dead stop and observing peak RPM achieved. This is usually more accurate than brake stall. A general rule is to match stall to your engines peak torque curve, however vehicle weight, gears, tire size, etc. play a role as well. It is best to exactly match stall to your torque curve; don't overestimate your torque curve, as you will receive a converter with too low a stall speed and poor E.Ts. To make the right selection you can talk to our professionals that can get you the proper combination. How does stall speed affect street driving? Properly designed converters up to 3200 RPM will not affect Normal street driving. Stalls above 3200 for street driving can begin to feel like the converter is always slipping, which it is, resulting in poor economy as well as increased trans heat. How do I know what stall converter I need? Just let us know a few things about the vehicle, what engine modifications have been made, gear ratio, tire size and weight of vehicle. This will let us give you some suggestions. Do I need an auxiliary trans cooler with a high stall converter? An additional cooler should be installed on any vehicle that is used for towing. Street strip vehicles are not required an additional cooler. But remember to not stay in brake stall for extended periods, as this is when heat is generated. Normal street driving with a properly designed converter has no affect on heat; however, cooling is always a good thing to preserve trans and converter life and should be considered. Should I have a transbrake? A transbrake is used to launch at peak RPM and to achieve repeatability. Transbrakes are only suitable for strip use. Which converter should I run in my diesel engine? All diesel vehicles would benefit from a lower stall speed that better matches the lower RPM torque curve of the diesel engine. The determining factor for which converter is right, comes down to how the vehicle is used. Stock to slightly modified diesels will do fine with our lower stall, heavy duty billet steel cover torque converter. Diesels that are highly modified and tow heavy loads will get the most benefit from our four disc converter. The two converters are similar in the stall speed and performance they achieve. The main difference is the four disc eliminates converter clutch burnout by greatly increasing the lock-up holding area while pulling heavy loads uphill and being able to handle the increased torque of modified diesel engines. How long is the warranty? Roadrunner Converters offers a one-year warranty from date of purchase that covers repair or replacement of the torque converter as determined faulty by inspection at our factory. All four disc diesel converters have a three-year warranty. All expenses, labor, towing, fluid, etc. are not covered by this warranty. Please ask for a copy of our complete warranty.