Anybody want to school me on stall speed?

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PhillH

PhillH

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I have a basic idea how they work, gets the revs into the power band before launch, cam the engine for that power band. Thats about it. Ive read alot about the different stall speeds but haven't really been explained in detail how to pick one. First off, what is a stock set at? What's considered streetable, low end being easy to drive and high end being a pain? I'll be picking a cam soon and I know this is going to come up. The 360 is disassembled and ready to hit the machine shop now. Thanks in advance.
 
The best thing I done was call PTC. He told me how they were built and how they work. They best thing when you get one is to have someone build a stall to your liking and your motor.
 
Once you have picked a cam,know gear and tire size you can call a T.convertor supplier.They will want to know all this info and intended use(street/strip?).Are you using a 904 or 727?
 
It is dependent on engine build, cam specs, car weight, intended usage, tire size and rear gears. Once you have all of that set in stone, then have one custom built for your needs.
 
One thing that I cant figure out is how do you tell what stall it is by phycially looking at it?? Every TC I have seen does NOT have the stall hard stamped into the bell.
 
Hi PhilH,

From http://www.hardtail.com/techtips/selectingconverter.html


Here are some general guidelines for selecting a converter:

According to B&M, the stall speed should be rated at about 500-750 RPM under your engine's peak torque RPM. If you don't know this figure, be conservative in your estimate. You don't want to end up with a converter that has too high of a stall speed. Don't be too conservative, though - it is possible to get a converter with too low of a stall speed, which will have roughly the same effect as too high of a stall speed.

Know your camshaft specifications. If your cam has less than 220 degrees duration (@ 0.050" lift), which most street machines do, you make most of your torque down low in the RPM range, and you probably won't need more than a 2500 RPM stall speed, if even that much.

Have a good idea of your vehicle's weight. Remember, lighter vehicles will lower the rated stall speed; heavier vehicles will have the opposite effect.

High stall converters generate a lot of extra heat. The installation of an external transmission cooler is mandatory with a higher than stock stall speed converter. Actually, you should have one in there anyway. Heat is the number one killer of transmissions - 85% of all trannies die because of inadequate cooling.

The best advice I can give anyone buying a converter is to talk to the manufacturer. They know torque converters better than anybody, and can help you to select exactly the right converter for your combination. This article was designed to give you some insight into what is needed to determine the right converter, and to make you familiar with the terms and what you need to know to speak intelligently with the experts.
 
4spdragtop:
One thing that I cant figure out is how do you tell what stall it is by phycially looking at it?? Every TC I have seen does NOT have the stall hard stamped into the bell.
Click to expand...
Stall speed is dependent on amount of torque engine makes, the weight and gearing of vehicle as well as how converter is built. Let’s say we take the same converter and install it behind two different engines a small block (lower torque out-put) and a big block (higher torque out-put) in same car, that converter will stall at a higher speed behind the big block than the small block.

This is why you have to have all the build information of engine and drive train etc. so converter builder can estimate engine output and normal cruise rpm car will be operating on the street to come up with a compromise that is efficient on the street, and still delivers at the track. Also why a converter is not labeled as it depends what it is hooked to.

If you just pick a stall speed out of thin air, or decide your friend’s car’s stall is just the ticket for your machine chances are real good you will build an expensive turd, and will sooner or later be replacing that converter with one designed properly to match your car’s build.

Pick a stall too low, and the car will be a slug off the line, won’t like to get into the power band going up steep hills, and if you have cammed up the engine, it won’t want to sit still in traffic because idle speed is at or higher than stall speed. The other side of the coin, too high stall speed will feel like engine and transmission is connected by a big rubber band. Step on the gas in stop and go traffic, it revs up and up and then starts to go, run up a slight grade and it feels like the transmission is slipping. All this looseness, constant churning of transmission fluid in the converter when not locked up generates a lot of excess heat, wastes fuel, and destroys transmissions.
 
Sorry for hijacking PhillH

WJAJR and PoisonDart74 thanks for the insight, maybe I am thinking too much into this but this is the scenario. Dad bought a 67 cuda "S" 273. It came with 2 torque converters, 1 the factory orig and a fairly new one that was hooked to a 400hp 360. STD Non commando pistons in it. We put new cam, lifters, springs, timing chain and gears. It came time to install engine but we had to pick a torq conv. Which one?? I know the new cam and more play a role in picking a torq conv BUT the new one.....unknown stall cuz it wasnt stamped on it anywhere. We went with the new one as it was behind a 400 hp 360....and we didnt go factory orig as the cam we installed was a little bigger than orig 273 commando specs. So we have a torq conv which is working fine but dont know the stall. Seems simple enough for torq conv mfg to hardstamp it into the bell or somewhere. Thanks for the insight guys!
 
There's an easy way to get the two stall speeds if it's in the car:
For the brake stall - hold the brakes on and push the gas in drive. Where the tach stops is the brake stall speed. That is the lower of the two.
For the flash stall - drive the car in drive to about 30mph. Let it go into 3rd gear. Once it's there, press the gas as far as you can without having it downshift. The rpms the engine reaches and holds for a sec is the flash stall. It will be higher than the brake stall.
 
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