Trans question

['65 chevy lover]

When dealing with transmissions, what does the term "Stall speed" mean. Example 1750, 1800-2200, 2300-2600 stall mean?

[Wrenchbender Ret]

It pertains to automatic trans. It is the RPM the engine will go to before moveing the vehicle. Like if you hold your foot on the brake & accelerator at the same time the engine will reach that particular RPM. High stall speeds are used with high performance cams. It makes poor driveability. A low stall speed with an engine with good low seed torque makes a good driver.

[TJ's Chevy]

Like said...and here's some to ad for the heck of it...if you've ever watched videos of trucks or cars racing the 1/8 or 1/4 mile...you may have noticed that the versions with automatics are reving above idle...lets say for instance that you hear the engine spinning at 3000 rpm but the truck or car isn't moving...that is transmission stall...a 3000 rpm stall is for higher rpm engines...ones that reach peak torque at higher RPM's...for instance...a 3000 RPM stall on a stock cylinder would be totally wrong..why you ask? Because the stock 6 cylinder chevy peaks torque between the RPM's of 1600-2200....so a 1500 RPM stall would be much better....but for an engine that peaks torque at 4000 rpm like a big block...then 3000 rpm stall is fine. To sum up...stall is the amount of slippage allowed before the transmission "locks" so to speak.

[PGSigns]

Advertised stall speed is not always what you get. A convertor with a big block will stall more than the same one with a mild small block. So what they show them as is a ball park number. With a high performance engine with a big cam it may idle at 1200. For this engine it will need a convertor that is built a little looser so it acts like a stock convertor when stopped and not trying to stall the engine out. All out race convertors are not built at a specific stall speed but built to fit the entire combination of engine trans and car along with how the car will be raced. A 4000 stall convertor will act pretty normal with mild throttle inputs and can driven like a normal stock convertor. the vehicle will move when in gear and at idle if the brake is released. Now if you power brake it or use a trans brake it will allow the engine to rev a lot higher on the launch. Then there is the rpm a convertor will "flash" to and that is another thing that is tunable in a convertor. So it all comes down to for a stock engine they are not needed and when you build a evil engine it always best to call a convertor builder and get the one you need for what the plan is and not worry about the advertised stall.
Jimmy

['65 chevy lover]

Thanks to all for the replys. I am going to use a th350 behind a 450hp 383 stroker and was wondering what torque converter to get. Although I may "race" my truck a little bit, it will be far from a drag only truck. I probably will only drive it on the weekends and other times when I can't ride my motorcycle. Sounds like I will want it to be a fairly low stall speed to be user friendly. Thanks again for the replys. If anyone has further advice, it would be appreciated.

Thanks,
'65 Chevy Lover

[Irishbleueyes]

Get the stall that matches your cam, the engine has to make power before the converter kicks in or the engine will bog down and possibly stall out.Torque converters are basically an automatic clutch for automatic transmissions. High stall converters were the solutions when they realized that head work and camshafts made the horsepower however the lack of vacuum with those wild cams was crap and the power came on later in the RPM so the fix was to let the engine rev to were it made power without much load. Hence the stall speed of the converters. Daily driver cams run from 1500 rpm to 6500 rpm on the high side. Lower speed converters will still work if you wanna run it hard now and then.. Good luck