By Don Terrill (c) RacingSecrets.com
What needs to be decided and in what order:
1. Converter Size - This is physical size of the converter - the outside diameter. Choose too small and you'll end up with too much stall. Choose too large and you'll end up with too little stall or a converter that's very inefficient (high % of slippage).
2. Stator - A one-way clutch that creates torque multiplication. It's about half the diameter of the entire converter and located right in the middle. The stator decision will set many of the converter's characteristics.
3. Fin Angle - Placed towards the outside of the converter, these fins can be bent to fine-tune the stall speed of the converter. Radical changes in fin angle may point to the need for a different stator or maybe even a different size converter.
Questions that need to be answered:
1. Desired Stall Speed
2. Engines Torque Curve
3. Weight of Car
4. Transmission First Gear Ratio
5. Rear-End Ratio
Converter Nazis - Be warned, converter companies may not be thrilled with your request to pick your own specs. Here's a conversation I had with torque converter company in Indiana - I'm dying to name the company, but I'll restrain myself. I called to order a custom converter and was prepared to give what size,stator and fin angle I wanted - I was asked what made me think I knew more about converters than they did? I asked what made them think they knew more about my car than I did? Smart response? Guess not, they refused my request for a converter - "No Converter for You!!!" -What jar-heads.
How did I know what specs. I needed? I had a lot of experience with their converters and knowledge of their coding system for stators and fin angles - I also knew what a change to either would do to stall speed and efficiency. How? A long talk with one of the guys in their shop.
Advice for the torque converter industry - Print stator and fin angle specs in your catalog. Then explain the characteristics for each. It's the smartest thing Comp Cams ever did - listing cam lobe specs in the back oftheir catalog. We need a Comp Cams for the converter industry.
Freshen-up warning: Sending in a perfectly good converter for freshen-up can be risky - even if you don't request a stall speed change. If internal clearances are altered while welding the converter back together, the stall characteristics can change. Like I've always said about carburetors, if you've got a good one, don't turn it loose.
Summary:
1. Work with only one converter company
2. Let them pick your first few converters
3. Learn about their converters, stators, fin angles,etc.
4. Start picking your own converter specs
More technical tips:
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http://speedtalk.com/store.html
My Notes: Talk to racers whose cars are very consistent. Find out what brand of converter they use and why. Then find out who services them if done locally. We have someone we use locally who will cut open the converter, show you the inside, discuss with you the options and if time allows, do it right then. He will then weld it up and you can take it home with you. This is of course depending on how busy he is. It is quite interesting when you blow a converter to see the damage inside. Visually seeing it can help you understand how it all works better.
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