[Harlequin]

Ive heard this term many times before but, can sombody please explain to me what a person means by saying they have a 2500rpm stall converter on their strip car....

[dmorris1200]

Here are a few old posts of mine from other times.

[quote]Well here it is the way I understand it, maybe I'm just a little conservative. You need to find out what kind of driving your looking to do. Are you driving daily, highways, around town. Do you just want a car that only comes out on the weekends and will destroy anything off the line. These questions will help you determine what gears to put in the rear as they will control your engines operating rpm's. Then once you find out what your average rpms are during most of your driving (if you're driving this around regularly) you want to keep your stall speed below that. If you mostly cruise around at 2,500rpm and you have a 3,000rpm stall converter you will overheat your trans fluid over time. If bad enough she'll feel like she's slipping in and out of gear while driving. The main reason for using a high stall converter is for a race engine that can't idle. If you built an engine that hairy that it needs that high a stall speed you shouldn't be thinking about low gears anyway. I would finish the rear first and see where your rpms are. Then think about a converter. I would also recommend a trans temp gauge. Slippage creates heat so you want to monitor fluid temp closely after you change the converter. I'm running a 302ci engine in my car. About .471 lift, 218deg intake-228deg exhaust @ .050" on the cam. I'm building a 3.70 9-inch rear for her at the moment. After thats done I'll decide on a converter, but I'm thinking along the lines of a 2,000 to 2,400 TCI Breakaway or Saturday Night Special.<hr></blockquote>
[quote]Hi Harry, There's a previous topic titled 'Best Torque Converter Choice' that's worth reading. There's more to picking a torque converter than just your engine and trans. Your rear end ratio will also play a role. Some of this is explained in other post. "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 3,200rpm rating might provide approximately 2,800rpm of stall speed behind a mild small block V8, but about 5,000rpm behind a big block making 800-plus ft-lbs. of torque. While most converter manufactures list stall speed ranges, those numbers are very, very general guidelines; true stall speed is impossible to measure do to vehicle variables. 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." All that was a direct guote from a converter book. It's verry easy to over due it on a torque converter choice. How much driving you're doing, what kind of driving, average rpm's, all play a role. Hope this helps. <hr></blockquote>

Hope this helps. The stall converter basically allows slippage so the engines rpm's can be higher before the trans launches.

[willys36@aol.com]

Tourque converter fluid couplings look like a bagel cut in half, hollowed out and without the cream cheese. One half of the bagel is connected to the engine and the other half is connected to the transmission. These hollow torus' are filled with closely spaced radial vanes and the whole thing is filled with trans fluid. When the engine torus is rotated, the vales sling the trans fluid to the outer edge and it has nowhere to go but enter the transmission torus. Since the fluid is spinning as well as flowing into the trans tourus, it imparts torque to it. The torque is multiplied as the RPM squared (double the RPM and the tourque is 4 times greater). This torque is also a function of the diameter of the torus (to the 5th power! doesn't take much of a diameter change to affect torque. A 13" torus transmits 50% more torque than a 12" at the same operating condition). One feature of this drive system is that the drive half of the torus must be traveling faster than the driven side or torque is zero. Auto manufacturers try to limit this inefficiency by cramming in a lot of vanes that have little clearance. Thus a stock fluid coupling is 'tight' - it transmits maximum torque just above idle speed. In fact, it transmits so much torque that if the parking brake is on and you revved the engine, it would stall at a very low RPM. For a stock, low powered engine this could be as low as 1200RPM. With a more powerful engine, that 'stall speed' may be as high as 1800 RPM. Unfortunately, racing engines prefer to idle at higher RPMs and a drag car need to be in it's power range when it takes off from the starting line (5000 - 8000 RPM) and a stock fluid coupling wouldn't allow this to happen. To accomodate higer RPM engines, after-market manufacturers grind out the vanes in the torus' so there is more fluid slippage and the engine can be revved higher B4 it stalls. This is obviously a compromise - engine can rev to it's power zone easier but fluid coupling slippage is greater and gas mileage suffers.

A warm street engine needs a little looser unit and you see them advertised as 2000 stall or 2400 stall units. This number is a relative number since stall is dependent on what the engine is capable of doing. One of Kenny Bernstien's top fuel slugs wouldn't stall with a stock converter - it might launch it a few miles but it wouldn't stall! The trick is to find one that lets the engine work but doesn't destroy economy. NEVER use a racing unit, i.e. +3000 stall, on the street. Extreme slippage at low RPM would generate so much heat it would destroy the trans very quickly, not to mention the terrible gas mileage.

[ August 14, 2002: Message edited by: willys36@aol.com ]</p>

[Harlequin]

I get it now...thanks guys....

[scumdog]

Never heard of no such beast as a "stall convertor" is it related to a catalytic convertor? - I guess it's just a lazy mans way of saying "a 3,500rpm stall-speed torgue convertor", the key word being stall-speed would give the idea that maybe that's the speed the convertor virtualy ceases to "slip" and locks up, with a hot cam it lets the engine reach an efficient rev. range to make power straight away, I guess we have all seen a tunnel-rammed car with hot cam and stock torque convertor leaving the line at the drags - it dies then slowly picks up until it builds up enough revs to start making horsepower.. (I guess some people will talk about "slip-diffs" and "lift cams" at the same time they are talking about their "stall-convertors" :-)!!

[41willys]

Hey Scum, get a grip on yourself. Not everything in the world needs to be called by its full proper name. Most people know what you mean when "stall convertor" is said. Lighten up. <img src="graemlins/spank.gif" border="0" alt="[spank]" />

[hotrodit]

Variable pitch dynaflow as fitted to '58 Buick Ltd's, no clutch's in that box it was all fluid drive but had a kick down by means two oil pumps linked to the throttle linkage, giving higher oil pressure & changing the pitch of the vanes in the converter, thus putting more power down.
Just thought some of you guys might have been interested to know what Buick blew their money on in the 50's & scrapped the idea in '59.
A real shame the one's i had worked really good!

[willys36@aol.com]

Thanks for reminding me of the Dynaflow, Hot. I think AMC also had a lockup, super throwdown, hi-tek trans in the 50s also. there was some real state of the art going on in trans' back then that Detroit is just rediscovering recently.

[hotrodit]

Thought you'd remember, you have lots of knowledge up there, kool.

[Deuce]

[quote]Originally posted by hotrodit:
<strong>Variable pitch dynaflow as fitted to '58 Buick Ltd's, no clutch's in that box it was all fluid drive but had a kick down by means two oil pumps linked to the throttle linkage, giving higher oil pressure & changing the pitch of the vanes in the converter, thus putting more power down.
Just thought some of you guys might have been interested to know what Buick blew their money on in the 50's & scrapped the idea in '59.
A real shame the one's i had worked really good! </strong><hr></blockquote>


They did not scrap the idea completely. Turbo 400's had them in Buicks 65 - 67. Can be installed in a Chevrolet 400. Have one in my Turbo 400 that is in my 32 Roadster. Works great. I have a Kenne-Bell convertor 800/2800 .

[hotrodit]

Iteresting do ya have any more info, i like to know this stuff!