I have brain frost on this subject. I know basically what a converter does (Envision a fan pushing another fan) I also know that the faster cars usually have a higher stall speed. But for the life of me I can't really understand whay faster cars usully need a higher stall speed or what this stall speed is all about. Can someone explain this subject to me in very simple terms?

Try this link:

www.protorque.com (http://www.protorque.com)

Great link with a LOT of good info! Hope it helps!

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Jeremy J. Bennett
Team Chevelle #298
Currently Chevelle-less!
1972 Chevelle (http://www.chevelles.com/showroom/72CHEVELLE2.jpg) - Sold 6/16/00

I'm not the best guy to answer this question but I'll do my best. A torque converter will cause the automatic transmission to slip or "stall" until is reaches a certain RPM range. Imagine a car will a manual trans, you hold in the clutch and rev the engine until you reach say 2000 RPMs and then let it out. The car will leave more aggressively than if you had just let out the clutch from idle. The higher the RPM the more aggressive the car will leave generally. A torque conveter on an automatic transmission simulates this. The stall speed should be matched up to the engine's camshaft and torque curve. The stall speed allows the engine to rev higher into the torque curve before the trans starts to transfer the power.

I have never built an engine or installed a converter but I've read a lot of magazines. Guys, please correct me if I am wrong on anything.

Mikey, so if you have a BB wouldn't you suggest a lower stall than the same exact car except with a SB? Assuming the BB makes more tq earlier than a SB. What I'm trying to say is that since a BB makes more tq earlier than a SB (generally speaking) would'nt the SB need a higher stall?

Stall speed varies with different engine/chassis combinations and the same convertor. Theoretically the actual stall speed of a particular combination is with the engine at full throttle and the drivetrain locked up. The same convertor will generally have a higher stall speed with a higher torque engine than one with lower torque. It is difficult to determine the actual stall speed without a transbrake because the driveshaft will usually overcome the brakes and cause the car to move at full throttle. Sometimes you can keep it from slipping with a full manual shift auto trans in high gear and all four brakes locked. A higher rpm power range or lower torque engine will generally need a higher stall speed convertor than an engine with a lot of torque or a lower rpm power range. Then there's the weight of the car, gearing, tires, etc. Many variables are involved.

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von '69 300 Dlx SS TC #15 ACES #1575

Von is right....other factors such as vehicle weight and engine torque will affect stall speed.

Usually faster cars have a higher stall speed because they need it....think about it.

Here's a hypothetical example: a 468, 12:1 compression with a solid lifter 600" lift cam, 1050 cfm carb, etc...you'd probably think...wow! That thing makes some serious power. Right?

That whole combination will produce mammoth power, but it probably has a powerband of like 3400-7000...a stock converter wouldn't allow this motor to effectively get the car "out of the hole". However, a 4000 stall converter(high by typical street standards) would allow this car to storm out of the hole, and most probably pull the wheels of the ground.

I run a 10" 3200 stall converter. My motor makes power from 2500-6200.
Typically motors that are built to make serious power, will have a higher powerband, wich will require a higher stall converter.

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"A days pay on the wild side"
'67 Chevelle 396/Th400/4.10

[This message has been edited by Big Block Dave (edited 07-19-2000).]

Will the torque converter hook up at a lower rpm than its specified stall speed? Or do you have to launch from all stop lights and signs at 3200 rpm?

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72 Malibu 350

LUKE.

<BLOCKQUOTE>quote:</font><HR>Originally posted by ch_ev_el_le:
Will the torque converter hook up at a lower rpm than its specified stall speed? Or do you have to launch from all stop lights and signs at 3200 rpm?
<HR></BLOCKQUOTE>

No ya silly bastid! http://www.chevelles.com/forum/biggrin.gif
The car will drive underneath that rpm, but it will not truly "lock" until the stall rpm.

My converter is fairly "tight" for normal driving...it doesn't feel all that sloppy around town, but when you flat punch it from a stop, the tach needle instantly goes to 3000-3200; before tire spin.

I've had converters with less stall that felt "looser", where the converter was a 2800, but had a sloppier feel.

I hope that this covers the "loose/tight" issue.


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"A days pay on the wild side"
'67 Chevelle 396/Th400/4.10

Michael,you need to listen to Von and Big Block Dave on this one. Like I said I have read mags but I have not had any experience with it. I'm on the side line watching the game and the people who are playing have a better understanding of what is going on.

How much ET will you gain from going to a 'generic' converter to a custom converter do ya think? Say something like a TCI 3800 and a ATI 3800.

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"I'll kick your ass so hard, you can use my shoestrings for dental floss" Roy D. Mercer

Richard Dorrough
Tulsa, Ok
'68 Chevelle
'70 Nomad (CHVELLE)
ACES # 789
TC # 453