In a high performance application the so called “transmission cooler” that runs through the radiator is in all actuality a transmission fluid heater. The internal radiator transmission cooler will raise the temperature to normal operating temperature much faster. This make the transmission fluid flow much easier throughout the transmission giving you better fuel mileage. However, the temperatures that the radiator hits does not allow for the proper cooling properties that are needed with today’s high performancetransmissions. Most radiators have an operating temperature of about 200 degrees. There must be a 34.7 degree variance in temperature before an acceptable amount of cooling can occur. The proper way to insure that the correct amount of cooling is taking place would be to by-pass the radiator and go through an external transmission cooler. ACC Performance suggests a minimum of a 3/4” X 10” X 12” size cooler. The addition of an external transmission cooler can drop the transmission fluid temperature more than 10 degrees which can more than double the life of your transmission.
All torque converters operate off of the twisting force of the engine and fluid pressure versus the weight of the vehicle. Do you remember back when you put dual exhaust on a truck and it got a little better gas mileage and engine performance? Well, the reason is: It freed up the exhaust to a point that it would expand the RPM range with the better exhaust flow. It would even give you better midrange and upper RPM power. It also lowered the torque between idle and 2,400 RPM. This change in the pressure on the transmission fluid would lock up the sprag in the stator earlier. You would have to say that the converter locking up earlier allowed the vehicle to move with less RPM. This in turn will give the vehicle better mileage and upper RPM performance.