Thanks for the great educational video, and a huge thanks for not ruining it with crappy background music while you're talking. I don't know why some people are compelled to add annoying background music throughout the video.
This is a great video. Years ago I had a Rover 800 2.0 litre with ZF HP14 4-speed automatic gearbox. They were sold as Sterling in the US and I expect they had the 2.7 litre Honda engine over there. As I was having the engine and gearbox rebuilt I took the opportunity to have a custom-made torque converter. I told the torque converter company that I wanted the lowest stall speed possible. They said they could do it, but it wouldn't work as the engine would stall as soon as it was put in gear. I went away to think about it, and the maths involved, and I concluded that they were wrong, so I asked them to go ahead and build it that way. They supplied it to the mechanic who was putting the gearbox back together, and after having supplied it, someone higher up in the company rang him up and said, "We're sure it isn't going to work, so if you return it now before it's fitted, we'll put it back to normal at no extra cost". Clearly, the discussion about it had filtered up and someone more senior had eventually taken a look at the spec after it had already been despatched. I went away and thought about it again and simulated it in my head, and I concluded that I was simply going outside their normal envelope of experience, and that they were extrapolating linearly outside of their experience instead of in proportion to the cube root, which is indicated by the maths. Plus, I'd reached the point where I had to know if I was right or not. So I told the mechanic to go ahead and fit it. I've got to say that it was almost perfectly how I expected it to be, in that there was a bit of an extra 'kerthunk' when it went into Drive, and the engine vibrated a little more on tickover when stationary, as the torque converter was pulling harder at tickover, but it didn't even come close to stalling the engine. Driving through traffic was lovely, because a lot of the time I only needed to take my foot off the brake to keep up with slow traffic as it would creep at a much higher speed than normal. To make decent progress I only had to breathe on the accelerator and the first to second gear change was extra silky because then engine was revving so slowly when it happened. Commuting right across London at the time I managed to average 35mpg over a tankful, which is pretty good considering that it was a 2-litre, long and relatively heavy car, driving through one of the heaviest traffic areas of the UK for most of my journey each day. But I was especially delighted that my experiment had worked, and the experienced, qualified professionals were wrong. The downside is that at the traffic lights Grand Prix it was definitely slower, because the torque converter was holding the engine speed down to a lower speed all the way through each gear, but if you use a car for normal commuter driving and not racing, then a lower-stall-speed torque converter is much nicer to drive with.
When my dad explained a torque converter to me in 1964, I was amazed. Now almost 60 yrs L8R, I see this vid & I'm still amazed! Thanks so much for making & posting this.
I read a number of explanations over the years from 1979 to maybe 2005 and none of them mentioned the one-way clutch. But it never made sense the way the stator was said to divert the fluid and add to the torque unless there was also something to stop it from spinning backward. Finally, in 2005, I just added "one-way clutch" to a Google search on the subject and found a more complete explanation than I'd ever seen before. I guess I could have just asked a transmission shop, but the few I'd had reason to visit seemed too busy for educational questions.
Let me simplify this for everyone....the front spinny thing uses fluid to make the back spinny thing go around and around. The engine speed required for the front spinny thing to spin the back spinny thing when you mash the accelerator thingy as fast as you can is called the stall speed. I don't know why they call it stall speed because it doesn't stall when its spinning.
I watched several other videos on stall speed and was nothing but disappointed. All of those people need to come and watch this and get an education from you professor. Fantastic video and 100% convinced me of who I need to go to for parts.
As a student, I appreciate information that I can understand. This video helped me understand stall speed and the factors that influence its variability. Thank you.
Thank you for getting right to the point here and being actually educational. I know very little about how automatic transmissions work and i want to understand more so i’m gonna binge this whole series
Oh baby, this video packed a punch, I learned a lot, especially that I should call for recommendations even on a mils street combo, I finally get it. Excellent.
I was glad to hear that about the foot brake stall. I don't like power braking at all and don't do it. I've taught my sons it's an embarrassment. If the car won't spin the wheels on it's own free will then build a bigger engine.
I am getting started on my 1971 Nova build. Just got my 383 stoker built, I was thinking in my mind I need a 2,500 stall. I wake up this morning and this is the first video on my recommend list. LMAO 😂
Nice to know RUclips listens to or watches my text messages..... 5 hours ago I had this exact discussion with my buddy about stalls and tq converters lol
Turbo hydramatic 425s had a variable pitch stator. VERY efficient. Shame they quit making them. Caterpillar hydrostatic transmissions had a unique torque converter design... Ever seen one ?? Great video Sir.
Good afternoon, I have an edelbrock performer kit, for a 302, 81 of a bronco, they estimate 320 hp and 260 foot pounds of torque between 2000 and 4000 rpm (5500 rpm max). It has a 3-speed c6 box, standard differential and 33 wheels, I need to replace the torque converter, I appreciate your suggestion to choose the right one for these characteristics, the camshaft indicates, intake duration 204 degrees, exhaust duration 214 degrees, elevation intake .448", exhaust elevation .472", lobe separation 112 degrees, intake center line 107 degrees, vacuum 16", thank you very much and congratulations for the videos, they are of great help to incorporate knowledge.
@@HughesPerformance NO, thank you for building quality parts. That's something we lost in this country over the years is quality, but you guys understand quality. I inspected the 2500 converter and it's great! Keep up the good work. 👍
i really appreciate this video, in short the more you slow down the fluid coupling from happening/ efficiency the higher the stall speed/ the more torque can be output by engine without overriding torque converter, trans, etc. Thank you so much finally understandable. :)
very good presentation thanks for posting your host of knowledge i have a few questions id like to ask i will try giving you guys a call early next week thank you
Great video, very informative, in depth explanation delivered in an easy to understand presentation. That said, I have to aak....what in the world is the guy with the air tool destroying? I'm no transmission expert but I find it impossible to believe any transmission requires 20 minutes of off and on grinding with an airtool. Thanks again for the video. All the best.
I actually had a couple sent to me when I talked and said this is what the gearing is this is what the trans is set up as hp rating and what my customer is looking for. getting the right torque converter to every set up is always a good thing when dealing with the final set up no one wants to take back out the trans just to fix a issue
Great video! The only question I have is how much a typical car torque converter waster energy (in kW) when the transmission in on Drive, the engine idling and the car is hold on brakes? Does different stall speed affect this?
Great video on understanding converters. Some shops i have spoken to ask specific engine build details is this really needed. Also is converter diameter a big factor in achieving what is needed as in smaller engines need smaller diameter for it to work. Thanks ray
Yes, when we provide a torque converter recommendation we want to know as many engine specifics as possible as well as vehicle weight, rear gear ratio, rear tire size, how the vehicle will be used, etc.
I really appreciate the vid..My knowledge of "High stall" is to get the engine in the sweet spot when you stab it as well as be able to idle with a large cam(low manifold vac) but the actual size of the converter is much smaller as the stall speed increases (Factory V8 converter over 3500 rated converter)....I'd like to know is that a smaller oil volume thing...
Great question!! Thanks for commenting here. Oil volume inside a torque converter does indeed play a significant role in the stall speed characteristics and coupling efficiency of a torque converter. As torque converter diameter decreases, oil volume obviously decreases as well. As oil volume decreases, there is less fluid available to offer resistance against the impeller as the engine is running as well as less leverage being generated from the impeller to the turbine due to the smaller, shorter impeller vanes. Consequently, as more engine torque is applied to the impeller, a corresponding rise in stall speed occurs. Additionally, most smaller diameter torque converter cores typically come from OEM applications that feature small engine displacement with relatively low torque output. As a result, the impeller designs commonly used with many smaller diameter torque converter cores feature more neutral or even negative impeller vane angles. As the impeller vane angle becomes more neutral or negative, stall speed increases due to the higher RPM required to create efficient fluid acceleration between the impeller and turbine.
Can you talk about or make a video about convertor slip ?? I lost mph and et as my convertor aged. I still don’t understand why it happened and how to prevent it
do people upgrade torque converters to deal with larger mud tires ? Seems like a good idea to me. I know a lot regear. I don't hear many people talking about torque converters though which to me would make sense also.
The most important aspect of explaining stall speeds that you missed is uses of stall speeds. Why you'd want a low stall speed vs high stall speed. What benefits from low stall speed and high stall speeds. Should have done that just after you explained what stall.speed is at the beginning before going into what affects stall speed.
In my Dodge truck, I could foot-brake stall and get the same as static stall. I pressed foot down hard on the brakes, and also pulled the E-brake, and that was enough to keep the tires from spinning under a WOT punch. Got ~2200rpm
@@lost1mp Yeah really, in a dodge it won't put up with that long, sad when a company makes a worse slush box than GM does, but yet fiat dodge does LOL.
Some vehicles do have enough brake system holding power to achieve maximum converter stall speed. As engine torque output increases with modifications, that becomes much more difficult to achieve.
Thank you for this great explanation. I was wondering why does the slip ratio reduce as RPM increases, I.e.: if you have a flash stall of say 3,000 rpm then you have close to a 3,000 rpm difference in input shaft to output shaft speed, but once the engine reaches say 6,000 rpm the output shaft would be much closer to the input shaft speed. Thank you for explaining that centrifugal force enables the fluid to transfer more energy.
Sorry to be offtopic but does anyone know of a method to log back into an Instagram account? I stupidly lost my password. I would love any help you can give me!
@Jayce Jaime thanks so much for your reply. I found the site on google and im in the hacking process now. I see it takes quite some time so I will reply here later with my results.
Thank you for making these videos. Curious about stall speed application. I’m guessing a high rpm hydraulic hookup would be used for drag racing where ya only care about 4-8k rpm. A slow hydraulic hookup, say 800 rpm for a Diesel tractor. Am I in the ballpark?
Thanks for your support and for commenting! We really appreciate it!! You're definitely thinking along the right lines. The vast majority of torque converters that we build for dedicated drag racing applications will typically provide a flash RPM of anywhere from 4,500 RPM to as much as 7,000 RPM and beyond, depending on the application. We tailor the necessary stall speed characteristics and converter coupling point to each specific application when it comes to our custom converter builds. Modified street-driven diesel applications will typically utilize a torque converter that only provides around 1,000 - 1,500 RPM of flash stall speed. Due to the torque output of diesel engines and the relatively low RPM ceiling, diesel applications typically need a very low coupling point in the converter. Hope this helps!!
Up to the end of the 1967 model year, GM made "switch pitch" torque converters, which increased the stall speed if the accelerator was depressed most of the way. It seemed like the best of both worlds, but I've heard it could be a reliability trouble spot. Do any aftermarket builders make switch-pitch converters today?
Not usually as an automatic transmissions clutches are internal. And the new "manumatic" type automatics simply allow to specifically select an individual gear. Actual manual transmissions do not use a torque converter, just a clutch. To have both would require a massive bell housing and a very complicated hydraulic system from the transmission. Also, why would you want both? The complexety of an automatic is enough for most people. Why add to that by throwing an additional fly wheel clutch to the mix.
Lock-up torque converters first began use by US domestic manufacturers in 1978. A lock-up converter features a clutch inside the torque converter that applies at cruising speeds typically around 35 - 40 MPH depending on the application. This feature was originally incorporated by OEM's to help increase fuel efficiency and reduce engine emissions. The aftermarket has since adapted lock-up converter technology to some extreme high horsepower drag racing applications.
In the early days of automatics, there were actually Chryslers with a pedal-operated clutch and a fluid coupling (a torque converter without the stator). Some shifted automatically between 2 speeds, but you had to use the clutch to switch between "ranges". They were probably less confusing to drive than to explain. The comments on this video explain it better than I ever could. ruclips.net/video/p-wfIrtVUmk/видео.html Also, VW had something called an "Automatic Stick Shift" in the 1960s, with a torque-converter, a vacuum-operated clutch and a 3 speed manual gearbox. The clutch automatically disengaged if the transmission lever moved so the driver just had to shift. Both of these seemed kind of kludgy, but they still could idle in gear, and could be driven in high gear with no shifting as long as you weren't in a hurry.
Can you make a video dedicated to the Allison 1000 TC considerations and different applications. I want a truck that can do it all. Street, track, tow/haul. I'm at 454hHP de-torqued to 800 lbs. with a 120hp tune looking at getting a transmission built and throwing in a 250hp tune for my 68mm, 10mil.stroked CP3 and 60 over injectors. Goal of 750hHP/1300TQ.
We don't get into Allison transmission builds here at Hughes, nor do we offer much for the diesel market apart from the typical billet triple disc converters and deep pans. If you're looking for hardcore diesel performance transmissions then you really need to be dealing with Suncoast.
@@sswcustomsewing4276 so if I had a six-cylinder with the same transmission and put it behind the big block it will make more torque with the big block
You guys do anything with the new 6 & 8 speed Chevy trans stall converter .like camaro and trucks, About 2400 stall, something to handle a 1k idle, and lock for street, I want to swap one into a older car, with older engine,
What is the difference between a low hp max effort small cu in converter, like an NHRA stock eliminator like a K/SA, and say a 400hp bracket car of equal weight?
I've got a .060" over 427 12.5:1 CR, Single plane intake with a 800 cfm dbl pmp Holly. Solid lifter cam, Advertised Duration: 304 Duration at .050" : 258 Lobe Separation : 108 .615" lift, 400 THM 4:56 12-bolt posi in a 4000lb 72 C/10. Can you recommend what stall speed I need? This truck wont see much street, track truck mostly...Thanks!
Are there any markings/#s on torque converter to know if it's stock or performance ? (Part # ?) I bought a used C-4 with a converter. Was told it is 4,000 stall. Haven't found any #s to know if it's stock or performance.
Our part number 25-30LHD torque converter would work well with your combination. This is our Pro Street series billet single disc 265mm model featuring an advertised stall speed rating of 3,000 RPM. This converter works really well in high performance trucks; offering a nice overall blend between great drivability along with a significant improvement in overall acceleration and performance as compared to an OEM torque converter.
A steel stator is ultimately stronger than an aluminum stator. That being said, modern billet aluminum stator designs are incredibly strong as well. What it really boils down to is selecting the right stator design that will provide the correct flash RPM, torque multiplication, and converter coupling characteristics for a given combination. Correctly designed steel stators will typically (though not always) offer increased flash RPM, less torque multiplication, and greater converter coupling ability when compared to similar aluminum stator models.
So if I have a LS swapped conversion and I feel that at idle the engine is over powering the brakes do I get a bigger converter? Or should I consider a different automatic transmission with a lower first gear ratio
I have a 72 350 motor 4 Main with a turbo 400 miles it and I can’t get the torque converter with the torque transmission through a belt was a shift kit what do I need in the torque in the transmission it would work with that transmission
If you are running a converter with a stall speed of 2200 to 2600 and you are running at 65 mph on the freeway with the engine turning at 2000 rpm's at 65mpr will the torque converter, be slipping causing heat and poor efficiency?
I am so screwed! prior to watching the video, I ordered from you guys based on shelf stall speed, WTF!!! Ordered a 22-20L 2000 stall Hughes converter for my 64 Chevelle, 700r4, 350 zz-4 eng with 20" wheels and it just doesn't feel right, what a waste of time and money. this was based on Hughes recommendations my understanding is that this only equates to about a 1700 stall due to it being an A/T. Unfortunately, the guy I spoke with was very irritated with my lack of knowledge of torque converters and I felt he just wanted me off the ph. i do however like and support their product.
what stall do you recomend ? I have a 1982 dodge d150 short bed with mildly built 318 with stock 30 over flat top pistions with factory 360 Hipo cam . 727 auto none lockup with racing shift kit and rear is 8-1/4 with 3:55 gears . the front 15 x 7 with 235 /75/15 and rear is 15x 8-1/2 with 255/75/15 I was thinking 2000 stall ?????
i have a 55 bel air with a ls3 and a brian tooley stage 2 cam, the cam is advertised to use the stock converter..... it has a 6l80e trans with 350 gears and its against the converter when i stop. What converter would you recommend for this application. Thanks, great video.
The BTR LS3 Stage 2 camshaft really works better with a higher stall torque converter. It's a great cam, but it's barely tolerable with a stock torque converter. I recommend our part number 65-25L. This is our Street Master 6L80 model that will typically provide stall speed in the range of 2,400 - 2,600 RPM with a combo like yours, will provide more favorable idling characteristics in gear, and still maintain fantastic drivability.
So my truck makes 265 full at 2000 rpm. (Ford 300) if I foot brake it it does about 1500 rpm. Is there anyway to determine how to determine my stall speed based on that?. Its totally stock E4OD transmission
Maximum stall speed is determined by whatever RPM the engine will flash to upon initial acceleration under load whether that be from a stop or very slow roll. You can transition to wide open throttle immediately at the same time of releasing the foot brake at 1,500 RPM, observe the tachometer while doing so, and the initial flash RPM is the maximum stall speed of your converter. You'll probably only notice another 200 - 300 RPM of flash over your current footbrake stall speed with that combination.
I am Still Trying To Have My Older 7004 And My New Blue Print 383 Stroker Working Properly, I have PurchasedA Hughes 2600-2700 Stall Converter And The Engine was Surging I was Told To Unhook Plug On The Driver Side Of The Transmission .After Doing So The Engine Surge Has Gone Away But I Don't Want to Burn Up My Transmission. I Am Getting Conflicting Information On Whether Or Not This Will Happen. This Combination Is In My 55 Belair 2Dr. Htop Which I Have Owned For 51 Years And It Is A Beautiful Car! I Would Appreciate Any Assistance In Resolving This Problem! Thank You!
Can you tell me if there is anything like more or less hp or cam than one thinks that would cause the stall to be effected,I mean more or less than advertised?
I have a Dodge Charger 5.7 AWD and find there's not enough stall which makes the engine not rev enough when hitting the gas fully to get the performance it should compared to a RWD... What can be done for this?
Switch pitch torque converters can alter the stator vane angle (or "pitch") when the switch pitch feature is activated. The stall speed will increase when the feature is activated which contributes to faster engine & vehicle acceleration from a stop or low speed.
@@HughesPerformance Came to ask the same thing, I rebuilt an ST400 trans and stuck it behind a 472-inch Caddy in my rat rod but didn't fully understand how the switch-pitch function works. Thanks!
@@guardiandogoargentinos1385 I believe the solenoid that controlled the pitch of the vanes was connected to a switch that detected the throttle position, but it could easily have been connected to a manual switch.
Funny, he never answered the question posed... Stall speed is the speed at which the converter holds back or limits the engine speed if the transmission output is prohibited. When your torque converter prevents the power transfer from your engine to your transmission, it increases the engine’s RPM stalls. For example, when you press down on your gas pedal, the stall speed is the gap between where your vehicle ideals and begins to move. The more stall speed you have, the more pressure you have to put on the gas pedal before your car begins to move. Why is Torque Converter Stall Speed Important? High performance torque converters can do a lot for your vehicle when the proper stall speed is selected. For racing, the proper stall speed will increase your launch and get you off the line quicker. In towing, the proper stall speed will help your engine pass more power to your transmission, causing your tow capacity to increase. How To Choose the Right Stall Speed: When you are selecting the right stall speed for your vehicle, be sure to match the engine’s peak torque, torque curve and vehicle weight. Peak Torque - The maximum torque your engine can exert at a certain RPM. Torque Curve - The place where the engine has the maximum amount of power at a certain RPM. Vehicle Weight - The weight of your vehicle has a big impact on the measurement, and don’t forget to factor in aftermarket modifications. If you don’t know these exact specifications, we recommend giving a conservative estimate. If you over estimate, your stall speed will be lower than intended, which will reduce your torque converter’s performance. If you are unsure about these modifications, the experts for help. In general, the desired stall speed should be 500-700 RPM below the engine RPM at peak torque. This ensures a margin for application for the torque converter to take off. You don’t want to have to floor your gas pedal and wait a few seconds for your vehicle to move. Think of it as a balancing act.
What exactly is stall speed, and how does it affect your vehicle? With the introduction of the Banks Billet Torque Converter, you’ll hear a lot of talk about stall speed. What exactly is stall speed, and how does it affect your vehicle? This article assumes you have a basic knowledge of how torque converters work. If you’d like more in-depth detail, see “Understanding Torque Converters” elsewhere on this site. Let’s start by illustrating how the stall speed works. Even under light loads, a vehicle with an automatic transmission will start moving as soon as you take your foot off the brake. The stall speed comes into play under all load conditions. When we talk about stall speed, we’re referring to engine RPM. If the vehicle isn’t moving by the time the impeller reaches the stall speed, either it will start to move, or the engine RPM will no longer increase. In other words, stall speed is the engine RPM at which the torque converter transfers the power of the engine to the transmission. In the real world, the torque converter’s stall speed roughly equates to the clutch engagement point on a manual transmission. Let’s say you’re driving your stick-shift car around town. Normally, you’d give the car a little gas and ease off the clutch pedal gently enough to get a smooth start. Likewise, under most driving conditions the torque converter will start delivering power to the transmission at relatively low engine RPM. Now, let’s say you need lots of power, either to make a fast getaway or to start with a heavy load. You’d rev the engine up to a point where it delivers more power before letting up on the clutch pedal. It’s under those same circumstances that the stall speed becomes important. The torque converter will allow the engine to build RPM without turning the output shaft (the turbine) until the stall speed is reached. Unlike gas engines, diesels develop massive amounts of torque (pulling power) at low RPM - enough that it’s possible (and, in fact, desirable) to get a heavily-loaded diesel truck rolling by simply easing off the clutch without touching the accelerator. Banks’ dynamometer tests show that Ford’s 7.3 liter Power Stroke hits peak torque at 1,600 RPM and begins to drop off at around 1,850 RPM, while the Dodge’s 5.9L Cummins engine peaks at 1,400 RPM and drops off at 1,800 RPM. As RPM continues to rise, torque decreases even further. How would you translate this to a torque converter? With a low stall speed. But both the Ford and Dodge torque converters stall between 2,000 and 2,500 RPM - so with a heavy load, the torque converter won’t start turning the rear wheels until well beyond the engine’s torque peak. In this case, the stall speed is too high - it is literally impossible to get the engine’s full power to the rear wheels! In order to access all of the engine’s potential power, the stall speed must be lowered. Lowering the stall speed has another advantage: It reduces the transmission’s temperature. Let’s go inside a high-stall torque converter under heavy load. The impeller (input side) of the torque converter is spinning quickly, while the turbine (output side) is spinning slowly or not at all. The motion energy of the impeller is being converted into heat energy, most of which is passed on to the transmission fluid. The higher the stall speed, the more heat will be generated. Heat is the enemy of a transmission. You want to keep the fluid temperature as low as possible. With a lower stall speed, less time elapses before the motion energy of the impeller is converted to motion energy to drive the turbine, so the transmission runs cooler and lives longer. What many people don’t know is that the torque converter is a tunable device. Stall speed is determined by several factors, including the distance between the impeller and the turbine and the design of the stator. By properly modifying the converter’s internal components, it’s possible to alter the stall speed and create a torque converter that is tuned for a particular engine.
So stall speed is the amount of RPMs the engine has to make to get the driven wheels to turn? I can see how such an application would be needed for racing, but what is the advantage for street? Does the engine always have to hit the stall speed to make the car go? Say 3,000 stall speed. Does the engine have to reach 3,000 before the car will start to move? Sorry if I seem a bit thick, but this has always been somewhat confusing and have have yet to get a good answer. Your video did seem to help me understand, if I did indeed understand it correctly. Thanks.
The stock stall is the best until it’s not. Typically large cams will cause the need for a higher than stock stall. The stall speed needed will be based on all of what he said as far as variables. Also it’s not a on off operation. It will work in the same principles as stock but at a higher rpm. The stall is where in theory a X rpm the engine can push through your brakes. Hold your brake down and slowly press your throttle you will feel basically a breaking point then the vehicle begins to move. To low of a stall the cam lope will start to shake your vehicle and perhaps try to move the car eft.
A higher stall speed converter will still provide drive power to the wheels at engine RPM below the actual stall speed rating of a given converter. However, a higher stall speed converter will display a higher percentage of slippage as drive power is initially being generated to the wheels, much in the same manner of slipping a clutch on initial throttle application and acceleration in a vehicle equipped with a manual transmission.
Hughes Performance I have a 383 with a SS 23-2500 and it feels like I’m driving a snowmobile with shift points I can’t even feel. Do I need an 1800 SS converter? Throttle response to power feels sluggish and my shifting is so soft, I can’t feel it. I’m confused as I used to feel every shift point on my stock setup
This video is making my brain hurt but thank you for making his videos I'm not trying to build a race vehicle I'm trying to keep my old plow truck on the road and I'm trying to understand every system from bumper to bumper on a molecular level
Very good video! Thanks for not having lame music or a bunch of other theatrics, just straight to the education.
Yes!
But..but..but you've got to be a crowd pleaser at all costs because the dum dums make the rules!!
Thanks for the great educational video, and a huge thanks for not ruining it with crappy background music while you're talking. I don't know why some people are compelled to add annoying background music throughout the video.
Fuckin Aye
This is a great video. Years ago I had a Rover 800 2.0 litre with ZF HP14 4-speed automatic gearbox. They were sold as Sterling in the US and I expect they had the 2.7 litre Honda engine over there. As I was having the engine and gearbox rebuilt I took the opportunity to have a custom-made torque converter. I told the torque converter company that I wanted the lowest stall speed possible. They said they could do it, but it wouldn't work as the engine would stall as soon as it was put in gear. I went away to think about it, and the maths involved, and I concluded that they were wrong, so I asked them to go ahead and build it that way. They supplied it to the mechanic who was putting the gearbox back together, and after having supplied it, someone higher up in the company rang him up and said, "We're sure it isn't going to work, so if you return it now before it's fitted, we'll put it back to normal at no extra cost". Clearly, the discussion about it had filtered up and someone more senior had eventually taken a look at the spec after it had already been despatched. I went away and thought about it again and simulated it in my head, and I concluded that I was simply going outside their normal envelope of experience, and that they were extrapolating linearly outside of their experience instead of in proportion to the cube root, which is indicated by the maths. Plus, I'd reached the point where I had to know if I was right or not. So I told the mechanic to go ahead and fit it.
I've got to say that it was almost perfectly how I expected it to be, in that there was a bit of an extra 'kerthunk' when it went into Drive, and the engine vibrated a little more on tickover when stationary, as the torque converter was pulling harder at tickover, but it didn't even come close to stalling the engine. Driving through traffic was lovely, because a lot of the time I only needed to take my foot off the brake to keep up with slow traffic as it would creep at a much higher speed than normal. To make decent progress I only had to breathe on the accelerator and the first to second gear change was extra silky because then engine was revving so slowly when it happened. Commuting right across London at the time I managed to average 35mpg over a tankful, which is pretty good considering that it was a 2-litre, long and relatively heavy car, driving through one of the heaviest traffic areas of the UK for most of my journey each day. But I was especially delighted that my experiment had worked, and the experienced, qualified professionals were wrong. The downside is that at the traffic lights Grand Prix it was definitely slower, because the torque converter was holding the engine speed down to a lower speed all the way through each gear, but if you use a car for normal commuter driving and not racing, then a lower-stall-speed torque converter is much nicer to drive with.
When my dad explained a torque converter to me in 1964, I was amazed. Now almost 60 yrs L8R, I see this vid & I'm still amazed!
Thanks so much for making & posting this.
I read a number of explanations over the years from 1979 to maybe 2005 and none of them mentioned the one-way clutch. But it never made sense the way the stator was said to divert the fluid and add to the torque unless there was also something to stop it from spinning backward. Finally, in 2005, I just added "one-way clutch" to a Google search on the subject and found a more complete explanation than I'd ever seen before. I guess I could have just asked a transmission shop, but the few I'd had reason to visit seemed too busy for educational questions.
Let me simplify this for everyone....the front spinny thing uses fluid to make the back spinny thing go around and around. The engine speed required for the front spinny thing to spin the back spinny thing when you mash the accelerator thingy as fast as you can is called the stall speed. I don't know why they call it stall speed because it doesn't stall when its spinning.
The turbine is stalled.
It does stall out tho the fluid starts to move backwards actually
So the spinny spin spinner, spin the spinny spin spin?
and this is why i prefer a manual. 😂
@@jeffhaire1984you should get yourself an automatic transmission with 10 gears
I watched several other videos on stall speed and was nothing but disappointed. All of those people need to come and watch this and get an education from you professor. Fantastic video and 100% convinced me of who I need to go to for parts.
Well what a shock to pull up a video done by none other than PETE! Wow that caught me off guard.
As a student, I appreciate information that I can understand. This video helped me understand stall speed and the factors that influence its variability. Thank you.
Thanks for your kind words and your support!
I went through several other videos myself before finding this one!
That was the best in-depth explanation on torque converters I have ever heard.
Cheers😊
Thank you for getting right to the point here and being actually educational. I know very little about how automatic transmissions work and i want to understand more so i’m gonna binge this whole series
Oh baby, this video packed a punch, I learned a lot, especially that I should call for recommendations even on a mils street combo, I finally get it. Excellent.
Thank you!!
I was glad to hear that about the foot brake stall. I don't like power braking at all and don't do it. I've taught my sons it's an embarrassment. If the car won't spin the wheels on it's own free will then build a bigger engine.
Spining wheels at 60 mph it takes torque period!!!!! Engine gotta be on the money cant make the power if the engine not burning the fuel
I am getting started on my 1971 Nova build. Just got my 383 stoker built, I was thinking in my mind I need a 2,500 stall. I wake up this morning and this is the first video on my recommend list. LMAO 😂
Building a 74 nova going with a 350 and 2500 stall 700r4 3.73 gears
Then Super T-10 and 400 hp 5.3 ls
Nice to know RUclips listens to or watches my text messages..... 5 hours ago I had this exact discussion with my buddy about stalls and tq converters lol
Google says, "you're welcome" 😂😂😂
Hughes Performance lol!! Definitely got me subbed buddy!!
Turbo hydramatic 425s had a variable pitch stator. VERY efficient. Shame they quit making them.
Caterpillar hydrostatic transmissions had a unique torque converter design...
Ever seen one ??
Great video Sir.
We've rebuilt many variable pitch GM converters over the years, but not that particular Caterpillar unit you mentioned.
Once again, excellent, concise with some impeller/stator/turbine design details and stall speed clarification.
Good afternoon, I have an edelbrock performer kit, for a 302, 81 of a bronco, they estimate 320 hp and 260 foot pounds of torque between 2000 and 4000 rpm (5500 rpm max). It has a 3-speed c6 box, standard differential and 33 wheels, I need to replace the torque converter, I appreciate your suggestion to choose the right one for these characteristics, the camshaft indicates, intake duration 204 degrees, exhaust duration 214 degrees, elevation intake .448", exhaust elevation .472", lobe separation 112 degrees, intake center line 107 degrees, vacuum 16", thank you very much and congratulations for the videos, they are of great help to incorporate knowledge.
I just purchased a Hughes converter. Works great 👍👍
Thank you!!
@@HughesPerformance NO, thank you for building quality parts. That's something we lost in this country over the years is quality, but you guys understand quality. I inspected the 2500 converter and it's great! Keep up the good work. 👍
Best stall speed video on RUclips 👍
Can’t wait to get my 408 sbm with twins together to start building the A999 to go behind it. You’ll be hearing from me.
i really appreciate this video, in short the more you slow down the fluid coupling from happening/ efficiency the higher the stall speed/ the more torque can be output by engine without overriding torque converter, trans, etc. Thank you so much finally understandable. :)
Very good! I tested a Dodge Dakota 3.9, V6 and I had 1600rpm. Is it right?
very good presentation thanks for posting your host of knowledge i have a few questions id like to ask i will try giving you guys a call early next week thank you
Great video, very informative, in depth explanation delivered in an easy to understand presentation.
That said, I have to aak....what in the world is the guy with the air tool destroying? I'm no transmission expert but I find it impossible to believe any transmission requires 20 minutes of off and on grinding with an airtool.
Thanks again for the video.
All the best.
Thankyou for sharing this video. I have a 02 silverado 1500, 5.3ls, 3.42 end, all stock. What stall would you recommend for towing, daily driver?
Great lesson, if I get into the market for a custom design I'm calling you! Thanks.
I actually had a couple sent to me when I talked and said this is what the gearing is this is what the trans is set up as hp rating and what my customer is looking for. getting the right torque converter to every set up is always a good thing when dealing with the final set up no one wants to take back out the trans just to fix a issue
Great video! The only question I have is how much a typical car torque converter waster energy (in kW) when the transmission in on Drive, the engine idling and the car is hold on brakes? Does different stall speed affect this?
This was exactly what I was looking for. Thanks 👍
If I install a stage 2 cam kit, will I need a different tipe of torque converter for a stick 5.3L?
Great video on understanding converters. Some shops i have spoken to ask specific engine build details is this really needed. Also is converter diameter a big factor in achieving what is needed as in smaller engines need smaller diameter for it to work. Thanks ray
Yes, when we provide a torque converter recommendation we want to know as many engine specifics as possible as well as vehicle weight, rear gear ratio, rear tire size, how the vehicle will be used, etc.
Bro! The banshee in the back ground 😂
I watched two of your explanation videos and knew right away to subscribe. Excellent and very helpful!
man, you are the best :) so nice for understanding about, thanks so much
Learned a lot, thank you.
I really appreciate the vid..My knowledge of "High stall" is to get the engine in the sweet spot when you stab it as well as be able to idle with a large cam(low manifold vac) but the actual size of the converter is much smaller as the stall speed increases (Factory V8 converter over 3500 rated converter)....I'd like to know is that a smaller oil volume thing...
Great question!! Thanks for commenting here. Oil volume inside a torque converter does indeed play a significant role in the stall speed characteristics and coupling efficiency of a torque converter.
As torque converter diameter decreases, oil volume obviously decreases as well. As oil volume decreases, there is less fluid available to offer resistance against the impeller as the engine is running as well as less leverage being generated from the impeller to the turbine due to the smaller, shorter impeller vanes. Consequently, as more engine torque is applied to the impeller, a corresponding rise in stall speed occurs.
Additionally, most smaller diameter torque converter cores typically come from OEM applications that feature small engine displacement with relatively low torque output. As a result, the impeller designs commonly used with many smaller diameter torque converter cores feature more neutral or even negative impeller vane angles. As the impeller vane angle becomes more neutral or negative, stall speed increases due to the higher RPM required to create efficient fluid acceleration between the impeller and turbine.
Every word is informative!❤️
Thank you so much. 🙂
I will definitely be calling.
Can you talk about or make a video about convertor slip ?? I lost mph and et as my convertor aged. I still don’t understand why it happened and how to prevent it
Will do!
do people upgrade torque converters to deal with larger mud tires ? Seems like a good idea to me. I know a lot regear. I don't hear many people talking about torque converters though which to me would make sense also.
love the channels. filled with great info 🤟🏾
Ok what is a reinforced converter? When I had my 200 4R trans built the builder recommended I get one.
This video really help me with my concern
Great video, thanks for taking some of the mystery out converters.
One question. When talking about measured stall speed did you say "Flat" stall speed or "Flash" stall speed?
"Flash"
Amazing video you said it best trust in this gent he knows what he says
The most important aspect of explaining stall speeds that you missed is uses of stall speeds. Why you'd want a low stall speed vs high stall speed. What benefits from low stall speed and high stall speeds. Should have done that just after you explained what stall.speed is at the beginning before going into what affects stall speed.
People have short attention spans....if you wanted to see this vid., you likely know what stall speed relates to IMO.
In my Dodge truck, I could foot-brake stall and get the same as static stall. I pressed foot down hard on the brakes, and also pulled the E-brake, and that was enough to keep the tires from spinning under a WOT punch. Got ~2200rpm
JoeIsCrazyWillman my condolences to your trans.
@@lost1mp Yeah really, in a dodge it won't put up with that long, sad when a company makes a worse slush box than GM does, but yet fiat dodge does LOL.
Some vehicles do have enough brake system holding power to achieve maximum converter stall speed. As engine torque output increases with modifications, that becomes much more difficult to achieve.
Thank you for this great explanation. I was wondering why does the slip ratio reduce as RPM increases, I.e.: if you have a flash stall of say 3,000 rpm then you have close to a 3,000 rpm difference in input shaft to output shaft speed, but once the engine reaches say 6,000 rpm the output shaft would be much closer to the input shaft speed. Thank you for explaining that centrifugal force enables the fluid to transfer more energy.
Sorry to be offtopic but does anyone know of a method to log back into an Instagram account?
I stupidly lost my password. I would love any help you can give me!
@Ronnie Randy Instablaster :)
@Jayce Jaime thanks so much for your reply. I found the site on google and im in the hacking process now.
I see it takes quite some time so I will reply here later with my results.
@Jayce Jaime It worked and I actually got access to my account again. I am so happy!
Thanks so much, you saved my ass !
@Ronnie Randy Happy to help :D
Can you assist me in a torque converter question on the correct torque converter for my setup?
amazing video...thanks...it's a generous amount of info to freely give to the car community.
Thank you for making these videos. Curious about stall speed application. I’m guessing a high rpm hydraulic hookup would be used for drag racing where ya only care about 4-8k rpm. A slow hydraulic hookup, say 800 rpm for a Diesel tractor. Am I in the ballpark?
Thanks for your support and for commenting! We really appreciate it!!
You're definitely thinking along the right lines. The vast majority of torque converters that we build for dedicated drag racing applications will typically provide a flash RPM of anywhere from 4,500 RPM to as much as 7,000 RPM and beyond, depending on the application. We tailor the necessary stall speed characteristics and converter coupling point to each specific application when it comes to our custom converter builds.
Modified street-driven diesel applications will typically utilize a torque converter that only provides around 1,000 - 1,500 RPM of flash stall speed. Due to the torque output of diesel engines and the relatively low RPM ceiling, diesel applications typically need a very low coupling point in the converter.
Hope this helps!!
I have a 2002 mustang gt stage 4 comp cams and 3200 stall converter do I need a tune again?
Excellent explanation. Great information-packed video.
Very interesting.
Previous to this I was pretty much in the dark as to how torque converters function.
👍
Up to the end of the 1967 model year, GM made "switch pitch" torque converters, which increased the stall speed if the accelerator was depressed most of the way. It seemed like the best of both worlds, but I've heard it could be a reliability trouble spot. Do any aftermarket builders make switch-pitch converters today?
Are there application for using both a torque converter and clutch at the same time?
Not usually as an automatic transmissions clutches are internal. And the new "manumatic" type automatics simply allow to specifically select an individual gear. Actual manual transmissions do not use a torque converter, just a clutch. To have both would require a massive bell housing and a very complicated hydraulic system from the transmission.
Also, why would you want both? The complexety of an automatic is enough for most people. Why add to that by throwing an additional fly wheel clutch to the mix.
Lock-up torque converters first began use by US domestic manufacturers in 1978. A lock-up converter features a clutch inside the torque converter that applies at cruising speeds typically around 35 - 40 MPH depending on the application. This feature was originally incorporated by OEM's to help increase fuel efficiency and reduce engine emissions. The aftermarket has since adapted lock-up converter technology to some extreme high horsepower drag racing applications.
In the early days of automatics, there were actually Chryslers with a pedal-operated clutch and a fluid coupling (a torque converter without the stator). Some shifted automatically between 2 speeds, but you had to use the clutch to switch between "ranges". They were probably less confusing to drive than to explain. The comments on this video explain it better than I ever could.
ruclips.net/video/p-wfIrtVUmk/видео.html
Also, VW had something called an "Automatic Stick Shift" in the 1960s, with a torque-converter, a vacuum-operated clutch and a 3 speed manual gearbox. The clutch automatically disengaged if the transmission lever moved so the driver just had to shift.
Both of these seemed kind of kludgy, but they still could idle in gear, and could be driven in high gear with no shifting as long as you weren't in a hurry.
Great video, thanks for the info!!!
Nice job with good tech.TY!
Can you tell us if more or less hp,torque or cam would effect the stall of the converter one buys,up or down?
Excellent video. I get it now. Thank you.
Can you make a video dedicated to the Allison 1000 TC considerations and different applications. I want a truck that can do it all. Street, track, tow/haul. I'm at 454hHP de-torqued to 800 lbs. with a 120hp tune looking at getting a transmission built and throwing in a 250hp tune for my 68mm, 10mil.stroked CP3 and 60 over injectors. Goal of 750hHP/1300TQ.
We don't get into Allison transmission builds here at Hughes, nor do we offer much for the diesel market apart from the typical billet triple disc converters and deep pans. If you're looking for hardcore diesel performance transmissions then you really need to be dealing with Suncoast.
Used Vega convertors with turbo 400 with shift kit and manual valve body and big blocks on the street for years.
I was thinking the same thing that worked yet they sure built some heat.
@@sswcustomsewing4276 so if I had a six-cylinder with the same transmission and put it behind the big block it will make more torque with the big block
I mean to say it would give it more stall
What is the lowest usable stall for a 2700 lb oval track race car.
4.88 rear gear.
You guys do anything with the new 6 & 8 speed Chevy trans stall converter .like camaro and trucks, About 2400 stall, something to handle a 1k idle, and lock for street, I want to swap one into a older car, with older engine,
We sure do! We have options available for the 6L80, 6L90, and 8L90.
Now on that flash stall speed is that just before redline and then you can tell what your stall speed is by rpm or before the trans changes gears?
I have a Hughes converter that I am running in my s10 pickup. Would Hughes have a record of my converter I purchased 6 years ago.
Does more vehicle weight require a higher or lower stall speed?
Lower because they weight of the vehicle will allow for more
What is the difference between a low hp max effort small cu in converter, like an NHRA stock eliminator like a K/SA, and say a 400hp bracket car of equal weight?
good explanation 🎉
I've got a .060" over 427 12.5:1 CR, Single plane intake with a 800 cfm dbl pmp Holly. Solid lifter cam, Advertised Duration: 304
Duration at .050" : 258
Lobe Separation : 108 .615" lift, 400 THM 4:56 12-bolt posi in a 4000lb 72 C/10. Can you recommend what stall speed I need? This truck wont see much street, track truck mostly...Thanks!
didn't know it was so complicated wow!
Are there any markings/#s on torque converter to know if it's stock or performance ? (Part # ?) I bought a used C-4 with a converter. Was told it is 4,000 stall. Haven't found any #s to know if it's stock or performance.
Excellent video
I have 1500 silverado with 4l80e and ls3 gt12 cam 373 gear what is best converter
Our part number 25-30LHD torque converter would work well with your combination. This is our Pro Street series billet single disc 265mm model featuring an advertised stall speed rating of 3,000 RPM. This converter works really well in high performance trucks; offering a nice overall blend between great drivability along with a significant improvement in overall acceleration and performance as compared to an OEM torque converter.
Thanks
What's the advantage of going with a steel stator compared to a aluminum stator ? Is it just that it can handle more power ?
A steel stator is ultimately stronger than an aluminum stator. That being said, modern billet aluminum stator designs are incredibly strong as well.
What it really boils down to is selecting the right stator design that will provide the correct flash RPM, torque multiplication, and converter coupling characteristics for a given combination.
Correctly designed steel stators will typically (though not always) offer increased flash RPM, less torque multiplication, and greater converter coupling ability when compared to similar aluminum stator models.
So if I have a LS swapped conversion and I feel that at idle the engine is over powering the brakes do I get a bigger converter? Or should I consider a different automatic transmission with a lower first gear ratio
I have a 72 350 motor 4 Main with a turbo 400 miles it and I can’t get the torque converter with the torque transmission through a belt was a shift kit what do I need in the torque in the transmission it would work with that transmission
Excellent engine and transmission combination right there. Hopefully you got everything figured out and have it running great.
I am confused. So, do higher rpm stalls above new specs indicate worn converters or do lower rpm stalls indicate worn fins or leak by?
So if I want to push more horsepower and torque on my 1999 CRV, would an aftermarket torque converter be ideal?
If you are running a converter with a stall speed of 2200 to 2600 and you are running at 65 mph on the freeway with the engine turning at 2000 rpm's at 65mpr will the torque converter, be slipping causing heat and poor efficiency?
I am so screwed! prior to watching the video, I ordered from you guys based on shelf stall speed, WTF!!! Ordered a 22-20L 2000 stall Hughes converter for my 64 Chevelle, 700r4, 350 zz-4 eng with 20" wheels and it just doesn't feel right, what a waste of time and money. this was based on Hughes recommendations my understanding is that this only equates to about a 1700 stall due to it being an A/T. Unfortunately, the guy I spoke with was very irritated with my lack of knowledge of torque converters and I felt he just wanted me off the ph. i do however like and support their product.
I’m beginning to remember why I would rather just have a manual transmission
what stall do you recomend ? I have a 1982 dodge d150 short bed with mildly built 318 with stock 30 over flat top pistions with factory 360 Hipo cam . 727 auto none lockup with racing shift kit and rear is 8-1/4 with 3:55 gears . the front 15 x 7 with 235 /75/15 and rear is 15x 8-1/2 with 255/75/15
I was thinking 2000 stall ?????
i have a 55 bel air with a ls3 and a brian tooley stage 2 cam, the cam is advertised to use the stock converter..... it has a 6l80e trans with 350 gears and its against the converter when i stop. What converter would you recommend for this application. Thanks, great video.
The BTR LS3 Stage 2 camshaft really works better with a higher stall torque converter. It's a great cam, but it's barely tolerable with a stock torque converter. I recommend our part number 65-25L. This is our Street Master 6L80 model that will typically provide stall speed in the range of 2,400 - 2,600 RPM with a combo like yours, will provide more favorable idling characteristics in gear, and still maintain fantastic drivability.
@@HughesPerformance Thanks for the response, i will be getting with you to order that converter.... Thanks
@@robertwilcox393 Do you recommend a trans cooler, or is it necessary.
@@bobwilcox5775 an external transmission fluid cooler is always a sound investment.
Can you take t400 with 10" convertor stalls 3500rpm change to 2500rpm with dump valves? Charging fluid? Thankyou
So my truck makes 265 full at 2000 rpm. (Ford 300) if I foot brake it it does about 1500 rpm. Is there anyway to determine how to determine my stall speed based on that?. Its totally stock E4OD transmission
Maximum stall speed is determined by whatever RPM the engine will flash to upon initial acceleration under load whether that be from a stop or very slow roll. You can transition to wide open throttle immediately at the same time of releasing the foot brake at 1,500 RPM, observe the tachometer while doing so, and the initial flash RPM is the maximum stall speed of your converter. You'll probably only notice another 200 - 300 RPM of flash over your current footbrake stall speed with that combination.
Fantastic video, thanks!!
I have a brand new Hughes 2500 torque converter in the box going in my S10.
I am Still Trying To Have My Older 7004 And My New Blue Print 383 Stroker Working Properly, I have PurchasedA Hughes 2600-2700 Stall Converter And The Engine was Surging I was Told To Unhook Plug On The Driver Side Of The Transmission .After Doing So The Engine Surge Has Gone Away But I Don't Want to Burn Up My Transmission. I Am Getting Conflicting Information On Whether Or Not This Will Happen. This Combination Is In My 55 Belair 2Dr. Htop Which I Have Owned For 51 Years And It Is A Beautiful Car! I Would Appreciate Any Assistance In Resolving This Problem! Thank You!
Can you tell me if there is anything like more or less hp or cam than one thinks that would cause the stall to be effected,I mean more or less than advertised?
Great Video ! Thank You
I have a Dodge Charger 5.7 AWD and find there's not enough stall which makes the engine not rev enough when hitting the gas fully to get the performance it should compared to a RWD... What can be done for this?
Thanks for the great video! What is going on with a GM Switch Pitch / variable vane torque converter? How do they work and do they have any benefits?
Switch pitch torque converters can alter the stator vane angle (or "pitch") when the switch pitch feature is activated. The stall speed will increase when the feature is activated which contributes to faster engine & vehicle acceleration from a stop or low speed.
@@HughesPerformance Came to ask the same thing, I rebuilt an ST400 trans and stuck it behind a 472-inch Caddy in my rat rod but didn't fully understand how the switch-pitch function works. Thanks!
@@HughesPerformance So, are you saying you can have a switch where you go from stock to high stall speed???!?
@@guardiandogoargentinos1385 I believe the solenoid that controlled the pitch of the vanes was connected to a switch that detected the throttle position, but it could easily have been connected to a manual switch.
Funny, he never answered the question posed... Stall speed is the speed at which the converter holds back or limits the engine speed if the transmission output is prohibited. When your torque converter prevents the power transfer from your engine to your transmission, it increases the engine’s RPM stalls. For example, when you press down on your gas pedal, the stall speed is the gap between where your vehicle ideals and begins to move. The more stall speed you have, the more pressure you have to put on the gas pedal before your car begins to move.
Why is Torque Converter Stall Speed Important?
High performance torque converters can do a lot for your vehicle when the proper stall speed is selected. For racing, the proper stall speed will increase your launch and get you off the line quicker. In towing, the proper stall speed will help your engine pass more power to your transmission, causing your tow capacity to increase.
How To Choose the Right Stall Speed:
When you are selecting the right stall speed for your vehicle, be sure to match the engine’s peak torque, torque curve and vehicle weight.
Peak Torque - The maximum torque your engine can exert at a certain RPM.
Torque Curve - The place where the engine has the maximum amount of power at a certain RPM.
Vehicle Weight - The weight of your vehicle has a big impact on the measurement, and don’t forget to factor in aftermarket modifications.
If you don’t know these exact specifications, we recommend giving a conservative estimate. If you over estimate, your stall speed will be lower than intended, which will reduce your torque converter’s performance. If you are unsure about these modifications, the experts for help.
In general, the desired stall speed should be 500-700 RPM below the engine RPM at peak torque. This ensures a margin for application for the torque converter to take off. You don’t want to have to floor your gas pedal and wait a few seconds for your vehicle to move. Think of it as a balancing act.
What exactly is stall speed, and how does it affect your vehicle?
With the introduction of the Banks Billet Torque Converter, you’ll hear a lot of talk about stall speed. What exactly is stall speed, and how does it affect your vehicle?
This article assumes you have a basic knowledge of how torque converters work. If you’d like more in-depth detail, see “Understanding Torque Converters” elsewhere on this site.
Let’s start by illustrating how the stall speed works. Even under light loads, a vehicle with an automatic transmission will start moving as soon as you take your foot off the brake. The stall speed comes into play under all load conditions. When we talk about stall speed, we’re referring to engine RPM. If the vehicle isn’t moving by the time the impeller reaches the stall speed, either it will start to move, or the engine RPM will no longer increase. In other words, stall speed is the engine RPM at which the torque converter transfers the power of the engine to the transmission.
In the real world, the torque converter’s stall speed roughly equates to the clutch engagement point on a manual transmission. Let’s say you’re driving your stick-shift car around town. Normally, you’d give the car a little gas and ease off the clutch pedal gently enough to get a smooth start. Likewise, under most driving conditions the torque converter will start delivering power to the transmission at relatively low engine RPM.
Now, let’s say you need lots of power, either to make a fast getaway or to start with a heavy load. You’d rev the engine up to a point where it delivers more power before letting up on the clutch pedal. It’s under those same circumstances that the stall speed becomes important. The torque converter will allow the engine to build RPM without turning the output shaft (the turbine) until the stall speed is reached.
Unlike gas engines, diesels develop massive amounts of torque (pulling power) at low RPM - enough that it’s possible (and, in fact, desirable) to get a heavily-loaded diesel truck rolling by simply easing off the clutch without touching the accelerator. Banks’ dynamometer tests show that Ford’s 7.3 liter Power Stroke hits peak torque at 1,600 RPM and begins to drop off at around 1,850 RPM, while the Dodge’s 5.9L Cummins engine peaks at 1,400 RPM and drops off at 1,800 RPM. As RPM continues to rise, torque decreases even further.
How would you translate this to a torque converter? With a low stall speed. But both the Ford and Dodge torque converters stall between 2,000 and 2,500 RPM - so with a heavy load, the torque converter won’t start turning the rear wheels until well beyond the engine’s torque peak. In this case, the stall speed is too high - it is literally impossible to get the engine’s full power to the rear wheels! In order to access all of the engine’s potential power, the stall speed must be lowered.
Lowering the stall speed has another advantage: It reduces the transmission’s temperature. Let’s go inside a high-stall torque converter under heavy load. The impeller (input side) of the torque converter is spinning quickly, while the turbine (output side) is spinning slowly or not at all. The motion energy of the impeller is being converted into heat energy, most of which is passed on to the transmission fluid. The higher the stall speed, the more heat will be generated. Heat is the enemy of a transmission. You want to keep the fluid temperature as low as possible. With a lower stall speed, less time elapses before the motion energy of the impeller is converted to motion energy to drive the turbine, so the transmission runs cooler and lives longer.
What many people don’t know is that the torque converter is a tunable device. Stall speed is determined by several factors, including the distance between the impeller and the turbine and the design of the stator. By properly modifying the converter’s internal components, it’s possible to alter the stall speed and create a torque converter that is tuned for a particular engine.
So stall speed is the amount of RPMs the engine has to make to get the driven wheels to turn? I can see how such an application would be needed for racing, but what is the advantage for street? Does the engine always have to hit the stall speed to make the car go? Say 3,000 stall speed. Does the engine have to reach 3,000 before the car will start to move? Sorry if I seem a bit thick, but this has always been somewhat confusing and have have yet to get a good answer. Your video did seem to help me understand, if I did indeed understand it correctly. Thanks.
The stock stall is the best until it’s not. Typically large cams will cause the need for a higher than stock stall. The stall speed needed will be based on all of what he said as far as variables. Also it’s not a on off operation. It will work in the same principles as stock but at a higher rpm. The stall is where in theory a X rpm the engine can push through your brakes. Hold your brake down and slowly press your throttle you will feel basically a breaking point then the vehicle begins to move. To low of a stall the cam lope will start to shake your vehicle and perhaps try to move the car eft.
A higher stall speed converter will still provide drive power to the wheels at engine RPM below the actual stall speed rating of a given converter. However, a higher stall speed converter will display a higher percentage of slippage as drive power is initially being generated to the wheels, much in the same manner of slipping a clutch on initial throttle application and acceleration in a vehicle equipped with a manual transmission.
Hughes Performance I have a 383 with a SS 23-2500 and it feels like I’m driving a snowmobile with shift points I can’t even feel. Do I need an 1800 SS converter? Throttle response to power feels sluggish and my shifting is so soft, I can’t feel it. I’m confused as I used to feel every shift point on my stock setup
Awsome video....very informative 👍
Great video .Thank`s.
Do u have any HP 2215 valve body replacement gaskets.
Yes, you can order those under part number HP2216 which comes as a pair.
@@HughesPerformance
Thanks for the response been a great transbrake.
so I have a 454 bored 030, 10.5:1CR, 280H comp cam, TH400, 3.42:1 posi rear and tires are 26" tall. what is the ideal torque converter?
This video is making my brain hurt but thank you for making his videos I'm not trying to build a race vehicle I'm trying to keep my old plow truck on the road and I'm trying to understand every system from bumper to bumper on a molecular level
all i want to know is what do i need for a 1/2 ton work truck with a small 4.8l v8 and 4L60E tranny? high or low stall speed?