How to Operate a Stall Converter

A stall converter is a modified converter designed to increase the torque applied to the wheels, which is useful in hauling heavy loads or, more frequently, for drag racing. A torque converter is the link between the engine and an automatic transmission. It allows the vehicle to come to a stop without stalling the engine. When the vehicle accelerates from a stop, fluid pressure rises with the rpm and it begins to apply power to the transmission. A modified stall converter allows the engine rpm to rise much higher before applying power to the transmission.

Instructions

1. Determine what amount of stall is necessary to meet the demand placed on it. Check the weight of the vehicle the stall is to be used in, the type of engine and what rpm it can achieve safely and what will it be used for. The bigger the displacement of the engine, the lower the stall should be. Big block engines produce so much torque they do not need very high stall converters. A stall of 2200 to 2500 is recommended unless it has monster slicks and a turbo or supercharger. Small block engines need a higher stall converter to build torque to accelerate. Torque is much more important to acceleration than horsepower.

2. Consider the pros and cons of using a high stall converter. A 2500 rpm stall converter will accelerate slowly without the need to raise the rpm; however, any type of moderate to heavy acceleration will immediately raise the rpm to the stall converter's lock up. Every time you accelerate it will sound as if the transmission is slipping. A stall converter gives a fabulous increase in acceleration but kills the fuel economy.

3. Install a stall converter if you have a large cam. The large cam creates problems idling with a stock converter since these engines idle higher than normal. A small 2500 rpm stall converter solves this problem.

4. Step on the brake pedal and raise the rpm to the stall limit before releasing the brake for faster acceleration

Tips & Warnings

• The first thing to understand is that horsepower is a product of rpm. A 300-horsepower engine may only have 45 hp at idle and the horsepower increases with rpm and achieving 300 hp at 5,500 rpm. A stock torque converter will lock up at 900 to 1000 rpm so when the vehicle is accelerated it starts with 45 hp. A stall converter is the same as a stick shift vehicle for the most part. If you want to accelerate fast from a stop with a stick shift it is necessary to rev the engine much higher than normal to increase the horsepower and let the clutch out quickly. A stall converter works the same. You can hold the brake so the car does not move and step on the gas to raise the rpm to whatever the stall converter rpm to lockup is before releasing the brake. Some stall converters will allow the car to lock up at up to 5000 rpm. Not practical for most engines but the engine is producing close to maximum horsepower.