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Thread: High Stall Torque Converter vs Low stall.

  1. #1
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    High Stall Torque Converter vs Low stall.

    Can someone tell me exactly the difference and the benefits of one over the other. I need to purchase one here fairly soon and was wondering if I should get a high stall torque converter. I heard someone say to me once that I wouldn't like it. Why is this? And what exactly does the high stall converter do differently from a stock one?

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    hmm..

    Anyone?

  3. #3
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    That's a great question... I am interested in the difference from stock to something like 2500.... I have a setup that should post over 350 rwhp & 450 rwtq. I know a 2500 stall would prove beneficial. But I like to take the car to work as well as the track. I am unsure what exactly this will do to the car...

    Details anyone?

    Anthony

  4. #4
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    What is a high stall converter?

    When you give the engine throttle with the brakes on, the RPM will only go so high. So a high stall converter allows you to launch from a standing start at higher RPM, and be in the max power band of the engine sooner.

  5. #5
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    Is it safe to say that I can't go to the store and get milk with letting lose? I didn't get too much understanding from that.

    Anthony

  6. #6
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    Re: What is a high stall converter?

    Originally posted by rivlee
    When you give the engine throttle with the brakes on, the RPM will only go so high. So a high stall converter allows you to launch from a standing start at higher RPM, and be in the max power band of the engine sooner.

    Alright, I understand that. So would you recommend a High stall converter for my car which has just slight modifications? Or keep a stock one. I can't launch very high with the one I got already because I spin to much as it is. Also what is the stock stall speed, and how much further would I want to go up? Thanks.

  7. #7
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    I'm still using a stock converter.

    Under brake, the tach shows a max of 22-2300rpm. Since I'm pumping out a lot more power than stock, it's probably a 2000rpm converter. I'm sure there's someone out there who can come up with the exact number.

    The effect of using a high stall converter is kind'a like "slipping the clutch".

    The other way to get the rpm up faster is to lower the diff gearing. The stock AOD rear is a fairly high 3.27. Because of the high torque of the SC, when you break the wheels loose, they want to keep spinning until you achieve some forward momentum. Going to a 3.73 it felt as if I'd lost half my torque, but the rpm went up quicker, less spin and faster 60ft times.

    Somebody like Duffy can probably give you a good technical explaination of this effect. I'm more a seat of the pants type who started with early Mustang big blocks. Wheel spin and hop was just a fact of life in those days and a lot of experimentation was needed to find some of the solutions that still work today.

    Lee
    Last edited by rivlee; 04-27-2003 at 07:12 AM.

  8. #8
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    There is a lot to say about converters. The most important thing to know about them is torque multiplication. Unlike sticks that transfer back a little less than what is given an auto actually multiplies the torque so if you were to measure torque numbers at the engine and after the converte,r the converter would have higher numbers. It actually works like a wound up spring. With a basically stock set up you would want to go to about a 2200-2300 stall, stock is about 2000 like said earlier. I am running a 3000 stall because I have a big cam that doesn't even like running under that. It has been said that a converter can give you .25 in the quarter. The higher stall will atually allow you to launch better on the street, it's kind of like slipping a clutch. Sure if you flash the converter, just floor it, it will rev up to the stall rpm and fry your tires but easing into it makes for a nice launch on the street. It also makes for a great launch at the strip with slicks on. Whenever you go to a higher rpm converter you should also add a larger tranny cooler because the slipping causes the fluid to heat up. Expect this mod to make the biggest difference in gas mileage too. A little more info just in case you are wondering, the car still moves at lower rpm but it just isn't fully engaged until you hit the stall rpm.

  9. #9
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    Here is a basic explanation of how I tell people to choose a stall for their car and the factors to consider.
    Mostly I will relate this to the aod and 4r70w transmissions.
    For the aod transmission you have a direct drive system. With this system you can run higher stall converter on the street and still get good gas mileage in 3rd and 4th gears. The downside to this is the driveline shock it exhibits. That and the terrible feeling the trans gives. Everybody thinks there is something wrong wih the transmission even when it is ok.
    For shift quality and all around smooth operation delete the direct drive and use a moderate stall (under 2500).For applicatons needing more stall than that keep the direct drive and set a street converter around 2800. This will give the best results.
    4r70w transmissions have a conventional lockup clutch. It will depend on gear selection and weight as to what stall a street driven car should run there.
    Gear ratio is a huge factor in determining stall. If you have a factory 2.73 gear don't buy a 3000 stall converter. It will exhibit driveability issues something terrible. When you fall below the required rpm of that converter to keep it on the "pull" side it will feel like it completely disconnects. Heavy throttle will be required to recover the rpm. This will give a jolt to the car and driver when it does recover. Sounds like fun right. Well try it happening about 40 times when you're climbing a light grade...In the rain.
    However if you have 4.10 gears 2800-3000 stall will feel like it was meant for the vehicle.
    Tire size plays a role in gear selection as well. Shorter tires may make a 2.73 gear act like a 3.08 because it changes the ratio accordingly. taller tires will naturally have the opposite effect. You see trucks running 4.56 and 4.88 gears with huge tires. They didn't do that for high rpm's they did it to make up for those enormous wheels. Most 4x4 trucks run best with low stall converters.
    Traction is a major factor in considering stall. The higher the stall of the converter the less traction you will feel like you have. If you're already fighting traction issues fix that before getting a higher stall converter. Most of the benefit of a big stall comes in takeoff. If it won't "hook" now more stall will make it worse. If you have the feeling that your car is strong but just doesn't give the hard "edge of traction" takeoff you want increase the stall accordingly. You will get the results you desire. Alot of people will tell you that a torque converter did more for there car than any other 1 item. There are definite benefits to more stall it just needs to be matched with your setup.
    Hope I shed a little light on this subject.
    Alan

  10. #10
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    Ok so can you build me a 9 inch converter for a aod I want it to stall at 27-2800. I do have the mods. my e-mail adress is in my profile. Tim

  11. #11
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    Quote Originally Posted by tim
    Ok so can you build me a 9 inch converter for a aod I want it to stall at 27-2800. I do have the mods. my e-mail adress is in my profile. Tim
    I can build indestructible 9.5 inch converters for these transmissions, thats a very low stall for a 9 inch converter. It would be cheaper to use an 11 inch converter rather than the 9.5 for that stall requirement. You have a pm
    Alan

  12. #12
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    Quote Originally Posted by ABConverters
    I can build indestructible 9.5 inch converters for these transmissions, thats a very low stall for a 9 inch converter. It would be cheaper to use an 11 inch converter rather than the 9.5 for that stall requirement. You have a pm
    Alan
    Here's a question. I've got a 2800 9.5" non-lockup convertor in my AOD. I'm trying to maximize my launch. What's the optimum way to launch? Should I rev to around 2800, then let off the brake and go? Or, should I rev to a lower rpm and let off the brake (while mashing the gas) and let the convertor flash.

    I've only had 5 passes on the new convertor and it appears that reving higher and then leaving seems the best, but I'd like to know from someone with more than 5 passes of experience.
    Kurt K (e-mail)
    SCCoA Member #: 443
    '92 SC AOD -- 11.521s @ 116.748mph, 2.0 AR power
    . . . . . . . . . -- 13.547s @ 101.01 mph, only w/ bolt-ons
    '95 SC 5spd -- All Stock, except 17" Simmons wheels.
    '90 SC 35th Anny 5spd -- 3rd owner, 16k miles
    2 '89 XR7 5spd's -- on their way out, really!

  13. #13
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    I'd tell you to try different things and see what gives your car the best results. Traction is always the issue. If you're blowing the tires off you need to rev to a lower rpm. If you're hooking up rev a little bit higher until you find the best place for your car.
    I'm seeing alot of people talking about 2800 stall 9.5 inch converters around here. I just don't get that an 11inch converter can deliver the same stall more efficiently and cheaper. I usually only build 245mm(9.5inch) converters in the 3000+ range. Plus non lockup on a 9.5 inch converter will build alot of heat. Non lockup(no direct drive as I call it) is great for racing,terrible for street and highway driving when used with a small diameter converter. I generally recommend deleting direct drive on 12 inch converters, It makes for a great feeling transmission.
    Alan

  14. #14
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    Can you build a 8 or 9 to 10 inch converter ,locking , with a 2400 stall?

    I want a smaller diameter converter to reduce wt.

    I have had my SC parked all year.Because of the info I have read about
    torque converters.Or mis-information.I am even close to junking the car
    over not being able to get converter info.Or a trans that lives over 300miles.

    How do you know what stall speed to buy in a torque converter,when you are building a new motor ? And have no dyno sheet numbers,to know rear wheel torque,or HP.

    Who builds the best AOD trans & torque converter money can buy ? Lentech,Art-Carr,you.

    Thanks Randy

  15. #15
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    I have not yet seen the lentech converter to be able to comment on it. I have seen a lentech trans and if they put as much effort into there converter as they do the trans it should be a nice piece.
    Art Carr builds several converters for these transmissions. Of the ones I have seen I can claim my converter to be better because of the billet front cover.
    Stay away from GER.
    As I stated I can build indestructible converters for these transmissions. The Key here is making the transmission strong enough to take it.
    Alan

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