Torque converter stall question

[BananaDan]

I have a moderate grasp on how they work, and I've been reading, but what I don't understand yet is how the normal driving of a car is changed when you install a bigger stall rated converter.  One question I have is, assume I replaced the stock converter on a 727 TF (2000-2300 stall I have read) with  a 2800-3200 stall rated converter.  Does that mean if I were at a red light and took my foot off the brake and slowly started to accelerate (not race, normal driving), the car wouldn't move forward until the engine hit ~2800 RPM's?

Dan

[Nacho-RT74]

will move forward, just will reach the max coupling at 2800.

is like gradually releasing the clutch pedal on a manual tranny, untill a complete clutch release at 2800.

[Brass]

I like my 11" converter from Turbo Action.  It's supposed to stall between 2800-3000 depending on torque.  Which means it allows the engine RPM to flash up into peak power without bogging. 

The piece I have was recommended to me by Ron (Firefighter) and will serve for a few years until future plans may call for something more aggressive.  (The right converter should be chosen with the rest of your build in mind.)  In the meantime, what I have works well.  It's very street-friendly.  I don't notice any difference unless the hammer is dropped; and then both tires are instantly ablaze.  The car is much more responsive than it was. 

Also, a transmission cooler is recommended if you go with a stall converter.  B&M makes a good one.

[Challenger340]

Boy, this could turn into a REALLY interesting conversation !

In a nutshell,
Don't be fooled by Convertors advertising the same stall speed, but 1 is waaay cheaper ?

The "slip" Characteristic under normal driving is the BIGGEST DIFFERENCE between the $1.99 Cheapo Stall Convertors, and spending MORE with a good Company like Turbo Action, and others, that build REAL Convertors ?

Stall, from a STOP, is easy for ANYBODY to do, just make the distance internal of the convertor "Loose", and presto you WILL get Stall,
BUT,
as the vehicle and the rear wheels move, ROTARY FLOW internal of the Convertor should start to overcome VORTEX Flow bringing it closer to "lock-Up",
BUT,
that REQUIRES some technology and manufacturing capabilities that entail REAL Fin Design,
something the Cheapo Convertor Guys don't do !

Anyways, IMO
TOO many people tend to judge convertors by "stall" only, failing to ever pay attention to Driving or MPH Efficiency characteristics.

Stick with a GOOD BRAND 2800-3200 stall convertor, and you should NOT Notice much difference in "Looseness" when leaving a light normally, and it engaging as Normal,
EXCEPT,
When you Mash the loud pedal and want it to stall.

[charge69]

Yes, I agree with Challenger340 wholeheartedly and have seen the difference between two supposedly same stall-speed converters make a big difference in real-world performance! You certainly aren't going to go around stoplight dragging anyone anywhere near all the time and a good converter can make a real difference.

I have seen a good manufacturer's 4000rpm stall converter lock up much tighter and provide better gas mileage in real world conditions than his cheaper 3000rpm converter from a cheaper source. The 3000rpm still slips at highway speed and his 4000rpm model was as tight as can be with a lower engine rpm on the highway and much nicer manners on the street. His recommendations definitely are "pay the money" and get as good a torque converter as you can and you will  be much happier with it.

By the way, the Turbo Action 4000rpm converter is on a 451" stroker with a solid roller cam and turns 11.10" @ 119mph thru the mufflers on a '69 Roadrunner that is ultra nice to see!

[Cooter]

 Does that mean if I were at a red light and took my foot off the brake and slowly started to accelerate (not race, normal driving), the car wouldn't move forward until the engine hit ~2800 RPM's?Yes and NO...On a "Cheap" converter, you will not notice a difference in stall speed from normal...However, once you get to around 4500-5500 stall speed RACE converter, then yes, you will think your driving an automatic that is slipping horribly...I once drove a 5000 Stall on the street, with 3.73 gear and it wouldn't begin to move until it hit around 3000 RPM, and by the time I was in high gear (3rd), I was out of motor(302 Ford)...I actually couldn't tell when the trans shifted as the RPM's STAYED at around 4500...But, as stated, there are many "Stall" converter manufacturers, but only a handfull of GOOD ones..You usually won't know it has a stall in the car, until you stomp the pedal...The best way for me to tell you what a stall converter acts like is to take your STOCK trans and stand on the brake, hit the throttle and as your RPM's go up, they will only go so far, then the converter "Stalls" the engine or the rear wheels begin to spin (IE: Power braking)...When you are running a stall converter and do this, the rear wheels will begin to spin LONG before you hit 3200 RPM's which is the "Flash" stall speed of the stall converter, as it is muliplying the torque much better by allowing the engine to reach it's powerband of the aftermarket camshaft.....

Dan

[BananaDan]

Thanks guys, this helps me understand it a lot better.  Let me clear one thing up, I am not looking for a cheap converter.  Firefighter Ron already recommended a Dynamic 11" converter and that is likely what I'll go with.  My trans has a stock (original I assume) converter in it now, and what I'm really trying to understand is what would be the difference felt in normal cruising/driving (not racing) between a stock converter and something like the Dynamic 11" which I believe is 2600-3200 stall.  I wouldn't be racing her lots, just occasional red light fun and maybe 1-2 trips to the track per year.

I have an Isky Mega 280 hydraulic cam in my 440 which is bored 30 over and has polished/ported 906 heads.  She has a stock intake, a Holley 750 DP, and Hooker Super Comp 2"/3.5" headers and a 3" exhaust with an X pipe and Magnaflow mufflers.

Dan

[BananaDan]

One other question.  You guys talk about stall as if it's good, or something you want.  Why is that?  When I hear stall, I think of two things.  One, bad clutch work on a manual car and the engine dies, and two, when you lose lift on a plane and it falls out of the sky.  Both to me are not something you would want.  Can you help me understand why you want stall on an automatic tranny's torque converter?   

[charge69]

Well, I will try to explain it but I don't know much about them in reality. You already have a good recommendation and the numbers to match (2600 to 3200rpm stall) and , if you buy this model converter , you will not notice much difference at all from the stock under normal driving conditions. The higher "stall" from stock only becomes more apparent when you step down hard on it, mainly from a standstill. The motor will be allowed to "flash" quickly up to the "stall" numbers which happen to be higher up in the RPM band where the motor is making more power. The rest is apparent... More in the power band means more power to the rear wheels and a better takeoff for you.

If you have a stock 440 converter, the extra 1000+rpm's you are getting to launch the car will definitely help make it quicker off the line. Stall speed converters and "stalling" an airplane which is dropping it below flying speed, are nothing in common either. Stalling an airplane, especially at low altitude, is gonna get you killed real soon. A higher stall converter, if a good one for the combiantion you have, will only manifest itself when you aggressively mash the "loud pedal" on your Charger. A very nice Charger, by the way!

[BananaDan]

Thanks, I've got it now.  I'm glad you guys could help me understand because my initial assumptions about what it meant led me to ignore and avoid people's recommendations to change my converter.  Now I see why I need one.

Dan

[Cooter]

Lemme put it this way Dan..
you got a hotter cam in your say 440, and you stand on it out the hole..It doesn't seem to want to "go" until around say 3000 RPM....

Dan goes home, gets on Dodge Charger .com and talks with the guys, buys Dynamic "Stall" converter, installs it, goes out in the street and stands on the same 440 and now has to buy new rear tires because he just can't get over how well his converter works with his engine now...

[BananaDan]

Yep, thanks Cooter.  That would explain why after getting her back on the road last year I was unable to break the tires ever.  I didn't try a lot or hard b/c the engine's fresh off rebuild so I've coddled her, but I could tell something was wrong, she has no balls out of the hole.  I legitimately tried once, I had her at a dead stop on an empty remote road.  I rev'd her up to 2000-2500ish RPMs with my foot on the brake and dropped the hammer and she accelerated similar to my old Dodge Neon.  Before I took her off the road for resto and engine rebuild I could break the tires without even trying and chirp from 1st to 2nd gear, occasionally from 2nd to 3rd but not often.  I miss not having my head pinned to the seat back.

Dan

[firefighter3931]

Not much to add to what's been said allready. The guys have given you an accurate description on how the right converter makes a world of difference ! 

I feel that the Dynamic 11in is a good match.  The Turbo Action 11in street hemi converter is also an excellent piece but is a little more expensive. Either would be a huge improvement 


Ron

[johnnycharger]

Hi guys,
I also need help on this topic. I have a 383 with a holley 750; edelbrock intake, headers, new exhaust, 410 rear end, and a 727 with a stage three shift kit. My tranny is leaking and I have it in the shop. They say it is caused by the torque converter and it needs to be replaced. What stall speed do I need, and any brand recommendations? My car is a weekend driver that jumps like a jack rabbit from signal light to signal light, but i want it to still drive nice. Thanks in advance!

[elacruze]

Bob, that's about the best converter post I've ever seen. 

I'll only add for Bananadan the difference between 'stall' and 'flash'-

'Convertor stall' is basically what RPM your engine can manage against the converter while holding the brakes, in a steady state.

'Convertor flash' is the RPM your engine will achieve against the convertor while launching the car, with a 'running start'-if you mash the gas from an idle, when the convertor hooks and moves the car, that's your flash RPM. Depending on the convertor, these two numbers may be close or different-Bob's point above is that a very good convertor will have a higher flash RPM than Stall RPM.

The entire point of both is to have your engine working at the torque peak at the flash, for fast launches but to stay connected at low enough RPM to drive it without the aggravation of slippage.

Man, convertor theory is a Rabbit Hole...

[johnnycharger]

Hi guys,
I hear reference to camshaft when discussing torque converters. I have a stock cam, but lots of other goodies. Will a 2800-3000 still be the best bet for me or should I stick to stock. Mostly street use with some red to red light fun.

[johnnycharger]

I am under crunch time from my tranny shop that has it on the floor, but I am thinking about going with the TCI Saturday night special.  Will I be disappointed?
thanks for your help with this guys!

[FLG]

You will most likely be dissapointed with anything tci make...too many horror stories.

Call dynamic, tell em what your doing and thell recommend a converter based on that.

[johnnycharger]

Thanks! I will contact them and see what they say! 

[Piston_Freddy]

Is this a stock converter? http://www.youtube.com/watch?v=G7Z0eWe0KPg  Ebay papers say that I should have a 3000 stall.

[FLG]

Freddy,

Your going to need to mash the pedal to the floor from a stop and see the rpm at which things start moving....generally its a bit lower than the stall that the converters rated with. But it should give you an idea.

[TUFCAT]

Hi Dan, I know this an old thread but what converter did you go with and how do you like it...

[oldcarnut]

I may not be asking this the right way but I'm going to ask another question since the way it works starting off was explained. But, what happens when your cruise/driving rpm is less than the stall rpm?  If the stall is 2600-3200 but your driving rpm is say 1700, what the effect on the tranny?

[FLG]

carnut,

A converter built by a reputable company (dynamic for example) will be able to stall high but still be efficient enough not to throw too much extra heat in the trans when just cruising. This is why its important to go with a quality converter, a cheap converter will wind up throwing a ton of excess heat into the trans due to its inefficiency.

Also an additional trans cooler is recommended, not just the stock one built into the radiator.

[Dino]

Man this stuff is confusing, I still don't really get it but I'll read up on it just so I can follow threads like these.

I still think that yanking the 727, smooth as it is, and replacing it with a 5 speed will give me a much more pleasant driving experience.  Heck I'd even bolt a GV unit on the auto if I could justify the cost but this 3 speed thing is ridiculous.   

[Cooter]

Man this stuff is confusing, I still don't really get it but I'll read up on it just so I can follow threads like these.

I still think that yanking the 727, smooth as it is, and replacing it with a 5 speed will give me a much more pleasant driving experience.  Heck I'd even bolt a GV unit on the auto if I could justify the cost but this 3 speed thing is ridiculous.   

Dino, I'll try and see if I can explain it as I do with some of my customers at the shop when looking into stall Converters....

Think of the inside of a Converter as a Paddle wheel on an old timey mill...Now, a stock converter will have little "vanes" that catch fluid being slung by them at a certain RPM. A Higher Stall converter will still have the vanes, but will be at a Steeper angle...Therefore, catching fluid that passes by takes more and more RPM in order to make the wheel turn...(More force). More force to turn Stator inside converter relates to more heat build up.
As a rule of thumb, if you like those "Bang Screech" shifts with a stock converter (Shift kit), then most times installing a Higher stall converter kinda "Covers up" the harsher shifts due to the extra slipping. however, depending on gear in rearend, this isn't always the case...

[Dino]

Ok I'm starting to get it now.  So by using a higher stall converter you are effectively putting it in the higher rpm range and thus higher hp and torque numbers which is great on the strip, but on the street it will act more like a slipping clutch which may give you the same benefits as on the strip but due to the slipping it generates more heat in the trans.  Am I kinda on the right track here?

So my car with its high rear end gear and (supposedly) stock converter will be good for a cruiser but even if I replace the rear end gear with a lower ratio I will still lose because of the low rpm stall converter?

Thanks for the explanation Cooter, sorry if I still messed up.   

[Cooter]

"Ok I'm starting to get it now.  So by using a higher stall converter you are effectively putting it in the higher rpm range and thus higher hp and torque numbers which is great on the strip, but on the street it will act more like a slipping clutch which may give you the same benefits as on the strip but due to the slipping it generates more heat in the trans.  Am I kinda on the right track here?"

YEP....



No, not at all Dino, in fact, now you know why Most ALL newer cars have a LOCK-UP Torque Converter in OD....

A high stall converter that never really "Stops stalling", or "Tightens up" will definately burn fluid. (Don;t ask me how I know. Something bout a 4500 RPM Converter in my 5.0 Stang, with 3.73:1 gear and trying to cruise it down the highway with a C4)....

Many of the newer trans's use Lock up Stall converters. So, while in the first three forward gears, you have the higher stall, but once in OD, it Locks up and doesn't stall anymore. Acts just like a Clutch in a manual.

[Dino]

"Ok I'm starting to get it now.  So by using a higher stall converter you are effectively putting it in the higher rpm range and thus higher hp and torque numbers which is great on the strip, but on the street it will act more like a slipping clutch which may give you the same benefits as on the strip but due to the slipping it generates more heat in the trans.  Am I kinda on the right track here?"

YEP....



No, not at all Dino, in fact, now you know why Most ALL newer cars have a LOCK-UP Torque Converter in OD....

A high stall converter that never really "Stops stalling", or "Tightens up" will definately burn fluid. (Don;t ask me how I know. Something bout a 4500 RPM Converter in my 5.0 Stang, with 3.73:1 gear and trying to cruise it down the highway with a C4)....

Many of the newer trans's use Lock up Stall converters. So, while in the first three forward gears, you have the higher stall, but once in OD, it Locks up and doesn't stall anymore. Acts just like a Clutch in a manual.

Awesome!  That actually makes sense to my little brain!  Thanks for the explanation Cooter.   

[TUFCAT]

I just re-read this thread from a couple of years ago...and man, there's some good info here!     I figure I'll bump it, in the event it can help someone else answer a question they forgot to ask....but always wanted to know.