stall converter

[cmegga]

Need some asistance selecting the right stall convert. I have close to a 400hp modified engine. It really doesnt make any power till 2500 rpm or so. I have the factory gears still in the rear end. I cant even get a chirp out of my tires right now, but I can leave tracks a 50 mph. I have some work done on the engine so figued I will change the converter while the engine is out.

Im looking for some thing that will inprove my take off. I dont want anything too drastice where Ill have to have the car at 3500 rpm to move. Its a daily driver and it sees alot of city and highway roads. I have just straight pipes and dont want too draw too much attention.

I dont know what was really in there factory. I was thinking I would go with some thing around 2000 - 2200 range. Is that going to be to low to make an inprovement ?

Anyone use one in this range ??

 

[Bob Chadwick]

If someone could explain what exactly the stall converter does and what difference the different RPM's make I would appreciate it.

Bob

 

[cmegga]

Also Can anyone confirm trans. for me. I believe the 81 came with the th350 ?? Is the correct ? Thanks again

 

[Nut]

cmegga,

'81's came only with the Turbo Hyrdomatic 350 automatic tranny. They are virtually bullet proof and last forever if maintained properly.

.............. Nut

 

[Bullitt]

Here's a link:Torque Converter It explains the inner workings of the converter. Also please note how they describe "not" to determine stall speed. You wouldn't believe how many people follow the incorrect method, even transmission shops.

--Bullitt

 

[Bob Chadwick]

Good information Bullit. Thanks. If I read the article correctly, Cmegga should be looking for a stall speed in the mid 2,000's, correct?

Where do these aftermarket shift kits fit into the scheme of things?

What speed is the stall converter on a 77?

Bob

 

[Bullitt]

Here's more:
http://www.phoenixtrans.com/html/faq.html
http://www.fbperformance.com/techtips/histall_converters.html
http://www.protorque.com/protorque_new/techi/ti_al.htm
http://www.bmracing.com/noflash/tech/torque.html
http://www.lingenfelter.com/torqueconvt.asp

Most pretty much say the same thing. I like Protorque, because they have pictures of the components.

Stall Speed

Nothing about torque converters is more misunderstood than stall speed. Stall speed is directly related to the amount of torque your engine produces--the more torque, the higher the stall speed. For example, a converter with a 2,800 to 3,200 rpm rating might provide approximately 2,800 rpm of stall speed behind
a mild small block V8, but about 5,000 rpm behind a big block making 800-plus ft.-lbs. of torque. If you don't know your engine's torque rating, you cannot establish the converter's stall speed.

That leads to perhaps the biggest problem people have when buying a converter: stall speed ratings. While most converter manufacturers list stall speed ranges, those numbers are very, very general guidelines; true stall speed is impossible to measure due to vehicle variables. The time-honored method
of testing a converter's stall speed--holding the brake and revving the engine while in gear--doesn't work, primarily because the tires will spin before you reach the converter's stall rpm.

The biggest complaint about converters centers on a stall speed that is too low. The problem is usually a lack of low-end torque, but there are other variables that can contribute to lower stall speeds, including the following:

Low vehicle weight
Small displacement engine
Very low compression ratio
Long duration camshafts
Retarded cam timing

Other Factors

Many people will send back a converter saying it doesn't fit their transmission's input shaft. Since performance converters are built to much closer tolerances than OEM types, the hub-to-input-shaft fit is tighter. That often leads people to think the new converter's hub is too small because they are used to just slipping the stock converter on. Usually, your new converter is OK--you just need a little extra effort to install it.

Heat is the biggest enemy of your converter and transmission. Stepping up to a higher stall converter can impose higher loads and create more heat, so proper cooling is essential. We strongly recommend a high capacity transmission cooler to protect your converter and transmission from damage.

--Bullitt

 

[Bullitt]

Bob, use the "flash" method to get a real close estimate of where you're converter stalls. Remember that you're not only finding out the stall speed for you convertor, but also how that stall corresponds to your car combination.

Shift kits for me, really don't factor in anywhere. I know some people like them, but what they do is increase the pressure inside the tranmission and create crisper shifts. That results in more heat, also. If you have marginal seals or just a tired tranny, you can count on impending leaks and more wear from both factors. In other words, just buy the right converter and don't worry about shift kits.

--Bullitt