torque converters

Can someone give a good explaination for what they do exactly and what the specification of say a 2600 stall converter means. Im going to get a rebuilt 700r4 and put a shift kit and the corvette servo in but i need to pick a stall. From what i have gathered it is best that you match the stall to your cam. i have a stock 305 and the cam sucks and i have no idea of the specs. What would be a good converter to have that would work well with my 305 and still allow a little for future improvments with the cam and overall power. I have read that a 1800 stall which is a stock s-10 converter works well. But i dont really know that. Thanks

A torque converter acts like a clutch does in a manual transmission. It transfers the engine power to the transmission. An 1800 stall would mean that the torque converter starts transferring power (i.e. putting a load on the engine) at approx. 1800 rpm. It would be similar to think of having a manual transmission, and revving the engine to 1800rpm, then letting out the clutch.

So anywhere below 1800 RPMS you have no power? Basically it's so that when you start out you are at the right place in your powerband, correct?

In a nutshell, the T/C is a fluid filled coupler to link the engine and transmission together insetad of physical contact like on a manual clutch system.

Stall speed works in relation to your camshafts power band (all depends on when your cam starts to wake things up if you will) in realtion to engine rpms.

For a stock application 1800 to 2K is just about right.

I'm sure seomone will chime in saying that's a pretty vague definition, but given your tone of question I think it's all you need to know for now.

So anywhere below 1800 RPMS you have no power? Basically it's so that when you start out you are at the right place in your powerband, correct?

Not really, it's when the stator locks or unlocks to transfer direct power, otherwise there's allowed slipage.

So with a 3000 stall, under 3k you will:

a) not move at all
b) move just fine, but you won't get any real power untill 3000
c) none of the above and I need to do some reading

So with a 3000 stall, under 3k you will:

a) not move at all
b) move just fine, but you won't get any real power untill 3000
c) none of the above and I need to do some reading


Pretty much B. The stator will freewheel until 3K then lock and apply full power to the spline shaft.

This is how a T/C goes bad, when the stator no longer functions correctly.

Ahh, okay. So what happens if you stick your foot in it from idle? It'll whine and complain untill you hit 3000 RPMs and then break your neck?

No, just won't transfer all the power to the driveline which brings up another point of the T/C, it is a Torque multiplier instead of using gears like in a man. trans.

So it would just feel like you're stuck in first gear so to speak

thats what it sounds like.....that would be pretty cool though....minus the neck breaking part of course :)

so would anything higher than 1800-2000 yeild any better results for me? I think the stock one on an rs is 700 is it not?....ewww let me slip in another question....tranny coolers....are they of much use in a street application? I know that when my motor is nice and cool and below that first bar( which seems to be the only time i can get any power out of the thing) I can sometimes bark the tire when going into second...not impressive i know but i think its cool.

Yeah that part would suck. But at least you would die your happiest, right? I mean what could be better than getting your neck broke by acceleration in your camaro? Good way to go, in my opinion.

so would anything higher than 1800-2000 yeild any better results for me? Depending on what you do with it, yes I think it should. Seems to me the higher into your powerband you can lock up, the better off you are. Well, within reason. I think the stock one on an rs is 700 is it not?....ewww let me slip in another question....tranny coolers....are they of much use in a street application? I have heard oth ways. Some say it wears your tranny more, some swear by it. I know over in the Grand Prix forum they shun them because those trannies have nearly never failed because of heat. I know that when my motor is nice and cool and below that first bar( which seems to be the only time i can get any power out of the thing) I can sometimes bark the tire when going into second...not impressive i know but i think its cool.

ok, let me clarify a few things on these. A stall converter is a fluid coupler. there is a housing with two propellers and a seperator called a stator. one propeller is connected to the engine, when the engine spins it forces fluid back through the stator and against the rear propeller, that turns the transmission. The converter does not lock up unless it is designed to. This is done through a manual style clutch on an electrical servo.

Stall speed is the maximum speed the engine can turn with the rear tires held still by the brakes.

flash point is the engine speed that it will zoom up to when you floor it.

Ahh, thank you so much. That made things quite clearer.

ok, let me clarify a few things on these. .

Thanks, I was having a blonde moment trying to spit it out in simple english.

no prob, words can be trickey ;) and converters are pretty confusing when you try to describe them accuratly, hence my ultra simplified explenation.

no prob, words can be trickey ;) and converters are pretty confusing when you try to describe them accuratly, hence my ultra simplified explenation.

ultra simplified:

the thingy that truns the whatchamacallit and applies the do-dad. :)

Little punchy this morn. sorry

To find a stall converter you want locate "TCI Automotive" 662-224-8972 www.tciauto.com These guys are the only company that dynos torque converters with a 675hp small block chevy instead of an electric motor. Give them your specs, give them what you want or are looking for, and they can give you an almost exact match to what you want. These guys on AF are good and can tell you how these things work, but nobody comes closer to telling you exactly what you want than the professionals. no offense to any of you. But TCI is probably your best bet, even if you don't buy from them, I have no idea how much it costs. They dyno -Stall speed -Torque Multiplication -Converter Efficiency (horsepower in divided by horsepower out) -Fluid Flow Volume -Fluid Temp in -Fluid Temp out -Fluid Pressure

all of this courtesy of Super Chevy Magazine July Issue.

no offence taken, i always suggest people go to the professionals, comp cams cam help anyone??? :) I will say that my mostly stock (only headers installed) tpi 350 loves the 2600 rpm stall i put in with my tranny rebuild, only problem is she dosnt like the 2.77 gears that came from the factory. the converter dosnt complement the gears so the tranny shifts a little funny. im gonna have to swap in a set of 3.27 gears to make it work right.

Quick question, how much money/time/work would I be looking at for putting a manual on an auto car? Any gains?

a proporly built auto is faster than a manual every time. only exception might be mario andretti and a formula one paddle shifted ferrari. Anyone who thinks they can shift a manual faster than my 700R4 in its current setup is very mistaken.

i think good ol Mario would beat you still in a soap box derby car.

Lol. Okay..... so the next question then would be, is the stock 1994 what you would call properly built? If so, how would I make one better, and if not, where would I go/do?

haha, factory stock, no thats not proporly built, thats called a slush box. the factory sets it up for soft shifts, to be appealing to the general public. but not the best for performance. a 94 has the 4l60 i believe, but definatly dont quote me on that.

So, what youll want to do is address the weak points of the factory setup. I stress that i did not do my tranny, i had it done by a trained and certified transmission tech, i strongly suggest you do that as well.

Here is what i did to my tranny, and most of it should apply to your tranny as well.

-Complete overhaul and rebuild with a B&M transkit with high performance clutch packs, bands, and spring changes.

-B&M shift kit (included in transkit) set to stage II for the firmest shifts given from higher line pressures due to altered shift body perameters.

-Corvette 1st to 2nd servo with a smaller line opening for extremely short off the line shifts.

-2600rpm torque converter with a kevlar lockup clutch.

just about all of those should transfer to your tranny, except maybe the corvette servo, but id bet there is something equivilent out there. I rebuilt my tranny to those specs, and it has without question been the biggest seat of the pants improovment i have done to date. the car was a completely different animal after i put that tranny in. I floored it with the shifter in drive, and peeled out onto the highway, when it shifted into second gear it was so fast and hard i was jerked back in the seat and pulled the shifter back into first gear, breaking the tires loose and going sideways till i shifted back up and got off the gas. It was crazy.

Dude, you almost died from putting a beefed trans in? Awesome. Thanks for the info.

died??? hardley, if i was gonna die it woulda happend a long time ago, im gonna live forever, i just went a little dukes of hazard for a second ;)

:icon16: That's pretty funny. You just need a General Lee now. I saw one in columbus pulled off on the highway, guy was under the hood.... complete with paint, push bar a wheels, it was awesome. I almost wanted to go back and take pix.

guy was under the hood....

Of course he was, it was a mopar. One of the best ones ever made but still a mopar.

i can't wait till I can do that in my car....

i kinda did the same thing with my 700R4... except I did the work myself. www.transmissionhead.com sold me all the parts. I have both servos that are supposed to be better than the corvette servos (35% more fluid apply area), kevlar band, red eagle clutches and stronger reaction shell (apparently a weak point after you get around 425-500hp). I also got pressure boost valve (.500") and I drilled out the fluid return holes in the oil pump so that the front seal doesn't get blown out.

My new engine isn't broken in yet (or even tuned for that matter) so i can't stomp the gas to see what it will do. but I did jack the rearend off the ground so that the wheels would spin freely, and that thing shifts quicker than anything I've ever been in! It's so quick that you don't even notice it shifted! (I'm sure I would though if it were on the ground). But it's quick! I'm pissed though because I don't have reverse. I think it has something to do with the servos.... I'll figure that out before the end of the week, then I'll be on the road.

I also bought the video from them that shows how to do all this stuff. it's very useful, and helps to understand how it works a little bit. $25 for the video.

No shift kit yet, heard bad things about the B&M kit (hear say)... I will get the Transgo shift plate soon... it will hold all gears manually. so you can select exactly what gear the trans is in, anytime: just like a manual transmission (without a clutch)that shifts a hell of a lot quicker. Getting a ratchet shifter later too. ($$$) Put a drain plug on the oil pan while you have it removed, it will make life easier... $7 at Oreily's.

I also put in 3 quarts of B&M trick shift. a couple of peope I have talked to said it made a noticable difference in their trannys. (I'm kinda getting scared of my car at this point :evillol: )

I might be interested in your parts, you got links?

oh yea..... I bought this trans off a guy in STL for $75 and it has a 2800-3000rpm stall converter in it already! Didn't know it until I took the car for it's first test drive, last week. I would recommend lower than that though, around 2000-2200rpm. my city gas mileage is really going to suck.

FireFox, are you asking me? if so, it's www.transmissionhead.com ... the parts are at the bottom of the page.

Stall has nothing to do with mileage as far as I know.

But i meant website links, not personal hookups and i-know-this-guy kinda thing.

the higher an engine revs, the more gas it is consuming..... mine will be revving at atleast 3000 all the time. more gas consumed, lower mileage.

still don't know what kind of links you want.
http://www.bmracing.com/
http://www.transgo.com/

Not at least 3000 all the time.

STALL SPEED = max RPMs that your engine can make without the swheels moving, i.e. with the breaks on. Your engine still idles and revs normally.

yea... it will idle, of course, but I meant with my foot on the gas.... while driving. because the stall is so high, the car barely moves below its stall speed. so it is necessary to rev higher in order to accelerate the car.

That doesn't sound right to me..... anyone else want to chime in? one or the other of us needs convincing.

hehe yeah, I need tons of help with a cam, I'm clueless when it comes to them things but I want to put one in my LS1 meanwhile keeping it street, emissions legal (New Jersey) and keeping the idle as smooth as possible...and I want to install it without removing the engine, is this possible? anyways that's another thread, continue with your story

firfox, i didnt mean to mislead you my definition of stall speed is correct, but it does effect your rpm band.

Let me try to explain. Your stall speed is determined by how loose or tight your converter is. A tight converter has a low rpm stall speed, but it accomplishes this by being very efficient and does not have alot of slippage. A loose converter has a high stall speed but accomplishes this by being inefficient and having alot of slippage, this slippage will increase your daily driving rpms and lower your gas mileage. Performance is almost always a trade off.

However, im confused because the 700R4 uses a lockup converter with an internal lockup clutch. which negates the loss of rpms at highway speeds. With my higher stall converter i get better off the line acceleration, however my highway cruizing has been uneffected.

Okay. I apologise Kevin.

Still learning, ha.....

So what would putting, say, a 3000 stall TC on an LT1 do?

improove acceleration off the line. youll want deeper gears to complement it like 3.42 or 3.73 gears. and youll want to keep the lockup option on the converter. so that your highway rpms will be low.

But driving in town will suck MPG-wise?

If that's the case, how much more MPG on top of that will you lose by accelerating hard? Say you go across town, hit 4 lights, and go 0-60 fast as you an each time? MPG will be way down right?

oh yeah, your gas mileage will suffer unless you are goin fast enough for the lockup feature of the converter to kick in.

Meaning over 3000, or does the lockup have a differant trigger?

lockup is controlled by a variety of factors, but the key factor is speed, it dosnt lock up under like 45mph or somethin.

Anyway to lock it up manually?

you can wire it to lockup in second gear, it wont do it in first gear no matter what. but you dont want to do this on a regular basis because it will burn up your lockup clutch. Its not designed for constant use like a real cluthch is, and the stress will probly burn it up within a week or two.

Blah. How much performance would you lose by keeping the stock TC, or atleast a lower stall like 2000-2500.

well you gotta remember, your parts should be balanced. Too much of something can be just as bad for performance as a stock part. Ive seen guys put a carb on that was too big, and it bogged the engine and had no throttle responce. so too much converter on a stock car would be a bad thing too. So if your car is otherwise stock youll want a lower stall converter. Ive already told you that i have a 2600 stall converter in my car and its too much for the gears i have. and i need to upgrade. So you have to do a lot of looking and match your components. there is no silver bullet, or single converter that is perfect or the end allpick that we could tell you.