The overall performance of most stock cars with stock engines is usually best when using stock converters. Minor changes in cam-shafts that push the power range up in RPM may require a different converter. If you find yourself in this situation, you will need to buy a new one. Keep the following in mind when trying to select a converter for your vehicle:
1.) Race Converters are Not for Regular Cars!
It is important to understand if your car is driven on a regular road, it is most likely not a race car. Race car converters will not provide satisfactory performance for a regular vehicle so do not waste your time looking at those types of converters.
2.) Select a Converter for Your Engine Type
Do not install a converter designed for a small-block into a car with a large-displacement or high torque engine. Some companies state right in their ads "not for use with big-block engines." This statement does not mean that the converter is low quality and the additional toque from a strong running big-block engine is going to kill it. This also means that the low-speed coupling efficiency is designed more for engines that produce less torque. High-torque big-block engines or even small-block engines with large displacement should use converters closely matched to their power output at lower engine speeds.
3.) Do not Add a Converter the is Too Loose with A Street RPM Engine
If you have a race car and you do this, you'll run out of RPM much too early in the quarter-mile race. Most vehicles are set up to go through the quarter-mile in high gear. It is important to keep in mind that the efficiency of converters is greatly influenced by the engine RPM at the trap seed. We've seen loose converters close nearly 1,000 RPM in high great and this should be factored into converter selection.
4.) Consider All Variables Such as Tire Size, Gear Ratio and Maximum RPM
All reputable part suppliers will ask about these aspects on your car prior to selling you your converter. Know all of these characteristics before going to buy your part.
The correct converter will provide some minor creep in Drive at your normal idle speed and will allow normal acceleration in traffic without excessive slippage and high RPM. It will provide a constant speed on the road without noticeable engine RPM changes when climbing and descending hills.
5.) A Torque-Converter Clutch can Improve your Converter
The torque-converter clutch (TCC) can be used to halt all torque multiplication for drag racing, road racing and many racers will use the TCC as early as second gear to provide a direct coupling between the engine and rear axle. This allows for a reliably loose converter to be used for maximum starting-line performance and still see the benefits of full power transfer during the run and lowest possible RPM at trap speeds.
The multiple-disk clutch assemblies increase the amount of friction material to greatly increase holding power when the TCC is applied. The pump cover and pump assembly are made of much stronger materials to hold their shape properly. These converters are available from most companies for applications where the user plans on using the TCC when the engine is making full power and they want all of the power produced to go directly to the transmission.