Someone explain TC's and stalls?

[Ghostyman25]

Ok...i know a little about automatics,mostly 4l60e's. I know nothing about TC's or stalls. Can someone explain how a TC works and how to properly choose a stall?

[custm2500]

I can't explain the insides but...
A stall is rated at what rpm it flashes to under load, therefore allowing the motor to make x amount of power vs. the much lower y horsepower at a lower rpm.

Cam is usually the biggest factor in stall speed. If you are putting a cam that has a operating range of 1600-4000 then you would want a stall of no less then 2000. Therefore the motor is not going to bog. Generally 2800-3200 stall is what most guys run in a street strip truck regardless of cam.

Under light throttle a mild stall(2000-3000) will feel virtually like stock. But when you power brake it you should get 75% or so of the stall speed then when you let off it will flash to the stall speed. Also if you punch the throttle for a stand still it will jump to the stall speed.

This is a VERY vague description and as simple as it can be made. IF you have more specific questions ask them and I/others will answer them.

[Ghostyman25]

Under light throttle a mild stall(2000-3000) will feel virtually like stock. But when you power brake it you should get 75% or so of the stall speed then when you let off it will flash to the stall speed. Also if you punch the throttle for a stand still it will jump to the stall speed.


Im not getting the "stall flashes to" parts. Are you talking about when it locks and unlocks? Im getting that from this spot of what you said ^ because when you brake it unlocks the TC correct?

[custm2500]

A torque converter is only locked at highway cruising speeds until then it may be putting power down but it is multiplying torque.Basically the input speed is slightly higher then the output speed. When it flashes to it's rpms that is when it puts power to the tires. Holding the brakes is called "brake stalling". When I launch my truck I hold the brakes and bring the rpm up to about 1000, then when the light goes green I mash the gas and let off the brake. The motor flashes to around 2800(my stall speed) before the converter starts to put the power into the transmission. I can bring my rpms as high as 1800-2000 before it will push through the brakes were a stock converter will do that at around 1000-1200 rpm.

The point of a higher stall is to the the motor into it's sweet spot and making the best horse power and torque for the launch. As I am sure you know your motor might make 100 hp and 100 ft. lb. or torque, At 2800 rpm it is making 200 horse power and 200 ft. lb. of torque. Kinda obvious how much better off you are. A stall will net you anywhere from a few tenths to commonly .5 or better in the quarter mile. Also a mild stall is great for towing if you have sufficient cooling for your trans.

Edit: Holding the brakes and keeping the rpm well below the converters stall speed is like idling wile holding the brakes on a stock stall.

[Ghostyman25]

Ok i got that now,seems simple when explained. Dare i even ask what to run in my 4.3? I kinda plan to get rid of the truck but if i can get a different stall for around the same price as the stock one and make it run better id love that.

[custm2500]

I would guess 2200-2800 would make a good differance. If you find a shop they can re-stall a stock replacement and should be able to do it fairly cheap. Any after market is going to run $600 and often closer to $800-$1000.

It is well worth it if you are looking for 1/4 times, more fun playing around, or if you tow with the truck. Obviously being a 4.3 you are going to want as much HP off the line to get it moving. A converter often drops .5 and more off your quarter and that mostly comes from leaving the line much better.

[Ghostyman25]

I would guess 2200-2800 would make a good differance. If you find a shop they can re-stall a stock replacement and should be able to do it fairly cheap. Any after market is going to run $600 and often closer to $800-$1000.

It is well worth it if you are looking for 1/4 times, more fun playing around, or if you tow with the truck. Obviously being a 4.3 you are going to want as much HP off the line to get it moving. A converter often drops .5 and more off your quarter and that mostly comes from leaving the line much better.

In that case ill just replace the stock one,IF i do keep the truck itll one day have a manual and 6.0...but for now its a DD and i dont plan on dropping a ton into a 4.3. I was just curious if this would be a simple replacement to get more hp/mpg while i have to replace the TC. I do mostly hwy driving and this doesnt seem helpful that much.