My understanding of automatic transmissions and torque converters is limited to hearsay, magazine articles, and bench racing sessions.
The picture I get on torque converters is:
1- For racing, legal or red-light, you can left foot brake, and get the engine RPM higher up in the torque curve before you launch.
2- The stall speed is the engine RPM where the drag of the torque converter drags the engine RPM down.
3- A higher stall speed torque converter will allow you to get higher up the torque band for a quicker launch.
4- For normal driving with a higher stall speed converter, the vehicle starts to move at a little higher engine RPM, but the difference is not as great as the difference in stall speeds between a stock and high performance converter.
Now if all that is true, and I'm far from sure it is:
A- What is the stall speed of our stock converter?
B- What would be the advantage of say, a 2800RPM stall converter, in normal traffic driving?
C- How about highway driving, does it affect mileage?
D- Does the higher stall converter produce more heat, higher trans fluid temperature?
I was going to email Greg with all my dumb questions, but I thought this might be of interest to other people who are AT/TC curious. So if anyone can enlighten me, please do. Or if you have perceptions about torque converters you aren't sure of, and would like confirmed, feel free to pitch in.
__________________
SSR Fanatics.....Knowledgeable friends, just a click away.
Last edited by xoxoxoBruce; 02-19-2011 at 02:29 PM.
Reason: Called Greg, Doug cause I'm stupid
My SSR: '05 Auto Redline Red #20727.... Born on 05/05/05...
Quote:
Originally Posted by xoxoxoBruce
My understanding of automatic transmissions and torque converters is limited to hearsay, magazine articles, and bench racing sessions.
The picture I get on torque converters is:
1- For racing, legal or red-light, you can left foot brake, and get the engine RPM higher up in the torque curve before you launch.
2- The stall speed is the engine RPM where the drag of the torque converter drags the engine RPM down.
3- A higher stall speed torque converter will allow you to get higher up the torque band for a quicker launch.
4- For normal driving with a higher stall speed converter, the vehicle starts to move at a little higher engine RPM, but the difference is not as great as the difference in stall speeds between a stock and high performance converter.
Now if all that is true, and I'm far from sure it is:
A- What is the stall speed of our stock converter?
B- What would be the advantage of say, a 2800RPM stall converter, in normal traffic driving?
C- How about highway driving, does it affect mileage?
D- Does the higher stall converter produce more heat, higher trans fluid temperature?
I was going to email Doug with all my dumb questions, but I thought this might be of interest to other people who are AT/TC curious. So if anyone can enlighten me, please do. Or if you have perceptions about torque converters you aren't sure of, and would like confirmed, feel free to pitch in.
but I thought this might be of interest to other people who are AT/TC curious. So if anyone can enlighten me, please do. Or if you have perceptions about torque converters you aren't sure of, and would like confirmed, feel free to pitch in.
I'm glad you address this as I'm not clear just what a change in torque converter would do for a pure bread 5.3 stocker engine like mine.
Last edited by RUN ROD RUN; 02-19-2011 at 02:02 PM.
1 You'll be able to do big smokin' tire burnouts, but your gas mileage will suffer ...2 Your 60 foot times will drop at the dragstrip, and so will the ET!
3 You can really impress your neighbors! (see #1)
Don J
Your gas mileage won't suffer if you have a lock up converter. I just ordered from Greg a custom 3000 stall convertor and a servo setup for mine. I discussed this package with Greg at last years Maggie Valley Rally. Greg told me this convertor will drive like stock, but when you hit it look out and hang on cause it is going to take off smokin' tires!
Due to the very technical nature of the converter and it's variants, I will try and keep this simple and easy to understand, however, I realize this is a deep subject and will be happy to answer any other questions about the torque converter in this thread, so evryone can try and get a better understanding.
The stock torque converter in the SSR is rated at about 1600 rpm stall speed. Stall speed is the the point where the converter is hydraulically peaked in it's ability to transfer engine power to the drivetrain. Most converters are about 85 percent efficient at peak stall speed so there is always some inherent slippage in the converter. The 4L60E-4L65E uses a "lock-up" torque converter, this type of converter has a clutch inside which locks both halves of the the converter to eliminate any internal slippage.The computer controls the amount of lock-up and when the lock-up occurs according to speed and throttle demand as well as temperature.
A torque converter, by design, multiplies engine torque to the driveline and by altering components in the torque converter, a builder can raise or lower the stall speed of any given converter and also change it's torque multiplication ratio. By using a smaller than stock diameter converter as a base unit, a builder can achieve a higher stall speed without a great loss of efficiency and excessive slippage. It is the slippage in a converter that generates heat, and the higher the stall speed, usually the higher the heat generated, another important reason to keep the lock-up function which eliminates this heat.
It is a common misconception that a higher stall converter will not allow a normal take-off and that it must rev much higher to get the vehicle rolling. This would only be true of some converters that have been far over modified for their diameter and made very inefficient. The stock converter on the SSR is 300MM, the safest stall speed modifications on this would take it to about 2200-2400 rpm. To go to higher stall speeds and still be efficient, converters for the SSR can be built in 280MM, 258MM and 245MM housings with stall speeds from 2600 all the way up to 4500rpm.These converters will "flash" to the higher stall speed under harder acceleration, but will usually be pretty docile in light throttle operation if properly built and matched to the vehicle and it's modifications.
The LS based engines in the SSR's are a much higher revving engine than the old small block designs of the past and torque peaks are much further up the rpm scale than older design engines. Adding an aftermarket cam profile and free flowing cylinder heads will increase power and torque but usually at the expense of bottom end performance. Anyone with a stock SSR knows that these are heavy vehicles and are not particularly strong out of the hole, usually struggling to even break traction from a standing wide open throttle start. Part of this is because the stock torque converter has such a low stall speed that the engine struggles to reach a powerband that will propel this heavy vehicle faster.
By installing a higher stall torque converter, the engine can rev much quicker to it's horsepower and torque peaks giving much faster acceleration under wide open throttle. This is true of both off the line and also when dropping into passing gear on the freeway.
There are some around town MPG penalties with a higher stall converter, but if chosen and designed correctly these penalties are quite minor, and highway mpg will not suffer at all due to the lock-up design.The biggest MPG drop will be in the first week after the converter is installed since you won't be able to keep your foot out of the throttle, it makes that much of a difference. In fact, swapping to a higher stall converter gives as much or more performance gain as a gear swap, and will not alter the highway cruising rpm like a steeper gear will do. A higher stall converter works great on an otherwise stock SSR to give greater acceleration without extensive engine modifications and will work with a stock tune and lower octane fuel.
My SSR: 05 6 sp. with 4.56 gears, ZR1 clutch, Edelbrock intake, Lunati cam, Crane rockers, C6 modified pan
Hey Greg, what do you know about the Porsche auto transmissions? My buddy took me for a ride in his brand new Panamera and I nosed through his owners manual. This thing has a button ( one of hundreds it seems ) that allows for a "fast getaway" that is supposed to give you a 5500 rpm launch??!! I'm guessing it unlocks the converter, but 5500 rpm??!! It warns to use this feature only for brief periods of time, I assume to keep fluid temps down. He didn't want to try it with 200 miles on the ride and I didn't encourage it period. What do you think?
As far as high perf. converters go what's your take on stall speed variation between steady brake torquing versus flashing the converter from an idle?
__________________
Veterans - all gave some and some gave all!
Greg, thanks so much for taken the time to explain all this. After reading it over a couple of times, a couple of questions pop into my head. Hope you don’t mind answering these as I’m sure you have better thing to do then setting in front of a computer.
Quote:
Originally Posted by Greg Ducato
The 4L60E-4L65E uses a "lock-up" torque converter, this type of converter has a clutch inside which locks both halves of the the converter to eliminate any internal slippage.The computer controls the amount of lock-up and when the lock-up occurs according to speed and throttle demand as well as temperature.
Can a plug in tune calibrate this? **
Quote:
It is the slippage in a converter that generates heat, and the higher the stall speed, usually the higher the heat generated, another important reason to keep the lock-up function which eliminates this heat.
Does adding a trans cooler help in any way with reducing the slippage heat?
Quote:
A higher stall converter works great on an otherwise stock SSR to give greater acceleration without extensive engine modifications and will work with a stock tune and lower octane fuel.
When you say greater acceleration …. Are you saying from a standing still point or from any point in MPH? … In other words, say I’m going uphill at 55 MPH and I want to pass a slower moving vehicle, will a better aftermarket the torque converter make passing that slow vehicle much easier?
** Is a re-tune required after changing the torque converter?
Greg, thanks so much for taken the time to explain all this. After reading it over a couple of times, a couple of questions pop into my head. Hope you don’t mind answering these as I’m sure you have better thing to do then setting in front of a computer.
Can a plug in tune calibrate this? **
Does adding a trans cooler help in any way with reducing the slippage heat?
When you say greater acceleration …. Are you saying from a standing still point or from any point in MPH? … In other words, say I’m going uphill at 55 MPH and I want to pass a slower moving vehicle, will a better aftermarket the torque converter make passing that slow vehicle much easier?
** Is a re-tune required after changing the torque converter?
RRR, I'm not Greg, but can help answer your questions.
1st yes a tune can change the lock up of the convertor. I don't know if a hand held tuner can, I do know HP Tuners and EFI Live can.
2nd Yes a cooler will help keep trans temps down. Running a higher stall convertor a cooler is allmost always a must to help keep trans temps under control.
3rd A higher stall when unlocked will help with acceleration accross the board.
4th A retune is not normaly required. I amnot going to retune mine when I install it and FYI I am on the stock trans tune in my 06.
Great job Greg. Simply put for us non-motor heads that can get it with an explanation as well done as that.
Question, for a mid range modification, to include the servo, what's a ball park price on a pure stock 6.0?
Get the convertor and servo setup Greg is sending me. It is a 3200 stall with good slow speed performance with the Corvette 2nd gear servo and a billet servo for 4th gear. This servo set up should eleminate any slipping of the band in 2nd and 4th gear. Mine is stock except for a tune, ported and polished throttle body and a hi flow muffler and with the convertor should wake it up and be able to spin the tires on takeoff!
Hey Greg, what do you know about the Porsche auto transmissions? My buddy took me for a ride in his brand new Panamera and I nosed through his owners manual. This thing has a button ( one of hundreds it seems ) that allows for a "fast getaway" that is supposed to give you a 5500 rpm launch??!! I'm guessing it unlocks the converter, but 5500 rpm??!! It warns to use this feature only for brief periods of time, I assume to keep fluid temps down. He didn't want to try it with 200 miles on the ride and I didn't encourage it period. What do you think?
As far as high perf. converters go what's your take on stall speed variation between steady brake torquing versus flashing the converter from an idle?
The Porsche trans is a dual clutch auto stick shift. It is a standard trans that shifts like an automatic and does not use a torque converter. There are several manufacturers going to this kind of trans.
We rate our converters at flash stall which is where the rest of the industry rates them. I do not recommend brake stalling, this overheats the trans and converter and does not allow proper suspension movement for an ideal launch. You will always be quicker with a stall converter leaving on the flash, unless you have a trans brake and suitably modified converter.
Greg, thanks so much for taken the time to explain all this. After reading it over a couple of times, a couple of questions pop into my head. Hope you don’t mind answering these as I’m sure you have better thing to do then setting in front of a computer.
Can a plug in tune calibrate this? **
Does adding a trans cooler help in any way with reducing the slippage heat?
When you say greater acceleration …. Are you saying from a standing still point or from any point in MPH? … In other words, say I’m going uphill at 55 MPH and I want to pass a slower moving vehicle, will a better aftermarket the torque converter make passing that slow vehicle much easier?
** Is a re-tune required after changing the torque converter?
Jeff, I don't know if a hand held tuner can adjust lock-up points but it can be done with some of the more sophisticated software.
A trans cooler will do well in managing heat , even in stock applications. It is certainly recommended when using a higher stall converter if you live in an area that is warm.
Yes, acceleration will improve in all aspects of driving
A re-tune is not required when installing a higher stall converter
My SSR: goodies by mike in az, lyndon wester, greg ducato, & sinister.
greg, what can i expect if i put a 3000 stall in my 04, it has 4.56 , preditor tune, flowmaster,vette servo,
will i still be able to drive down the hiway at 70mph and not have the converter flashing in and out?
or am i still thinking old school?
The torque converter in the 4L60E has a clutch in it which locks the converter when the computer commands it, thereby eliminating any stall or slippage. This component will allow you to cruise down the highway exactly as you would with a stock converter. The higher stall speed converter will make as much or more difference in acceleration as the the 4.56 gears did for you.
I've run a couple of Circle D specialties converters in my trucks, if we end up with a A4 it will probably get 1 as well. Chris will custom tailor a converter to your needs.
My 278mm setup at 2600 drove like stock, with very minimal MPG affect.
Shift extensions were great and the launch difference was night and day.
not trying to step on anyones toes, just giving another option
Last edited by PEWTERLIFTEDZ; 03-22-2011 at 11:41 AM.
I've run a couple of Circle D specialties converters in my trucks, if we end up with a A4 it will probably get 1 as well. Chris will custom tailor a converter to your needs.
My 278mm setup at 2600 drove like stock, with very minimal MPG affect.
Shift extensions were great and the launch difference was night and day.
not trying to step on anyones toes.
If I could find a trustworthy transmission shop in the Orange County California area, I would have one of Greg's high stall converters installed by now. To bad for me, Greg's shop is so far away. At this point in time, he would be the only guy I would trust to provide the right performance converter.
My SSR: goodies by mike in az, lyndon wester, greg ducato, & sinister.
Quote:
Originally Posted by KRUISSR
If I could find a trustworthy transmission shop in the Orange County California area, I would have one of Greg's high stall converters installed by now. To bad for me, Greg's shop is so far away. At this point in time, he would be the only guy I would trust to provide the right performance converter.
i know how you feel !!!
my brother inlaw has a tranny shop up , so i'm not too worried.
If I could find a trustworthy transmission shop in the Orange County California area, I would have one of Greg's high stall converters installed by now. To bad for me, Greg's shop is so far away. At this point in time, he would be the only guy I would trust to provide the right performance converter.
I would have though they would be a number of good transmission shops in the Huntington Beach area.
Suggest you PM Art (hdflstf) as he use to live down that way and he might just know the person or shop for you to call.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
Trustworthy Shop
Linear Mode
