Torque Converter Stall Speed Calculator

The stall speed of a torque converter is the RPM at which it begins transferring power from the engine to the transmission — matching it to your engine and drivetrain setup is critical for launch performance. Enter your engine horsepower, vehicle weight, fuel type, primary usage, transmission manufacturer, first gear ratio, rear gear ratio, and whether you're running a trans brake into the Torque Converter Stall Speed Calculator. You'll get a recommended stall speed in RPM, a low-to-high stall speed range, and your converter slip percentage.

HP
lbs

Fuel Type *

Trans Brake *

Results

Recommended Stall Speed

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Stall Speed Range (Low)

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Stall Speed Range (High)

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Converter Slip Percentage

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Frequently Asked Questions

What does a torque converter do?

A torque converter connects the engine to the transmission in automatic transmissions, transferring power through hydraulic fluid while allowing the engine to continue running when the vehicle is stopped.

What stall converter do I need?

The ideal stall speed depends on your engine's power band, vehicle weight, transmission gearing, and intended use. Street cars typically need 2000-2800 RPM stall, while drag racing applications may need 3000-5000+ RPM stall.

What is the difference between flash stall and foot-brake stall?

Flash stall is the RPM the converter reaches under full throttle acceleration from a stop. Foot-brake stall is the RPM reached when holding the brakes and applying full throttle, typically 200-400 RPM lower than flash stall.

How does vehicle weight affect stall speed selection?

Heavier vehicles need lower stall speeds to get moving efficiently, while lighter vehicles can benefit from higher stall speeds to keep the engine in its power band during acceleration.

What happens if my stall speed is too high?

A stall speed that's too high will cause poor fuel economy, excessive heat generation, sluggish low-speed performance, and potential transmission damage from overheating.

What happens if my stall speed is too low?

A stall speed that's too low may cause the engine to bog down during acceleration, poor performance off the line, and inability to properly utilize the engine's power band.

Do I need a different stall speed for drag racing vs street driving?

Yes, drag racing typically requires higher stall speeds (3000-5000+ RPM) to launch at peak torque, while street driving needs lower stall speeds (2000-2800 RPM) for fuel economy and drivability.

How does transmission gearing affect stall speed selection?

Lower (numerically higher) first gear ratios and rear axle ratios allow for higher stall speeds, while higher (numerically lower) gear ratios typically require lower stall speeds for optimal performance.