When I had my 400 trans rebuilt the guy put a new converter in it. I'm getting a new cam put in tomorrow and am wondering what is the diff between a stall and a torque converter. Are they the same? Can't ask the guy who rebuilt it, he's on vacation. Thanks

 

C'mon guys I don't know didley about this, help me?

 

Every torque converter has a rated stall speed. Without getting too technical its a measure of how 'loose' the converter is. That is, how high the engine will rev before the converter locks up. Thats a gross oversimplification but it will help you understand the concept. A stock converter stalls at about 12-1500 rpm. High perf street is usually 18-2500. Strip converters start at about 3000 rpm. A high stall converter allows the engine to rev into the rpm range where it makes power. Hope this helps.

 

Check out these 2 links to get an understanding of what stall is and the basic function of a torque converter-
http://www.bankspower.com/techarticl...ng-Stall-Speed

http://www.tciauto.com/Products/Tech..._explained.asp

 

Well, that was a resonable description, but not totally correct. Stall speed is a measure of the energy absorption of the torque converter. And stall speed for a converter is dependent on the performance of the engine to which it is 'married'. When an automatic transmission is tested, the output of the transmission is locked to prevent rotation (akin to putting the car in Drive and locking the brakes so the car cannot move). Then the input to the torque converter is spun and "input torque" is set to a fixed value. (This value simulates the torque capability of the car's engine at the rpm equivalent to the designed stall speed; ie/ a stock C3 SB might produce 150 ft-lbs of torque at 1800 rpm [stall speed for that converter design]). Once the input torque has been set, the actual input speed that results is the "Stall Speed" measure for that individual converter.

Now, if that same converter is placed in a transmission behind a 454 engine, the resulting stall speed will be much higher...because of the higher torque capability of that engine. So, to get a properly sized torque converter, you need to know the torque/hp capabilities of your engine and the stall speed you wish to have. For 'normal' driving situations, a stall speed of 1500-1800 rpm is appropriate. For drag racing situations, you want to have a converter stall speed where the engine produces just enough torque to obtain a maximum potential launch (considering the tires, rear axle ratio, etc, etc.). That might mean a stall speed of 2500-3000 rpm...or even higher.

The message here, is that a specific torque converter can have any number of stall speed ratings...dependent on the torque/power of the engine to which it is matched. That is why you need to supply the two pieces of information listed above to a qualified technician/engineer who can select the proper torque converter for you. If you buy a converter from a reputable manufacturer, they have technical folks who can help you with this selection process. But, expecting to get the proper converter from the guy behind the counter of your local parts store is like 'expecting' to hit the lottery this Saturday...

 

That's an excellent explanation, but we all know that stuff because we've been doing this a long time. But give the poor guy a break. He didn't know if stall and converter were two different things. He's just starting out. We were all there once. I think a simple explanation is more appropriate. And I do expect to win the lottery this Saturday.

 

No expert on converters here, but finding one that work's well for your current street set up can be a trying ordeal. Once you find the right combination, good to stick with it, as can be rebuilt if needed. Most common problem is a groove worn in the converter hub, and these can be replaced by a knowledgeable shop.