stall changes with HP and the 6.5 made something near 200 so if your making 150 or lower stall would get lower to but i dont think you should have any problems with fighting the motor at idle much even if you bump it up a little

 

Is this from experience?

6.5L had 180 hp @ 3,400 rpm and 360 lb·ft @ 1,700 rpm

The 4bd can match this, even exceed with a properly matched turbo and intercooler with some injection pump tuning. I don't know how far Adam R plans to push his 4bd.

But I have to disagree with you on the "stall changes with HP". In a gas engine yes it makes sense that a higher stall is used with higher HP. But usually the reason for the higher stall is because of the a cam that has increased the HP has also moved the HP and torque further into the RPM range. So the off idle drive ability has gone down, requiring a high stall.

Also HP doesn't have anything to do with leaving a light or crawling or idle for that matter. Torque is what gets you moving.

You suggest he lowers the 6.5L torque converter stall for the 4bd? How come?

 

Do not have any input on the 4L80 side other than that sounds like a great price.

On my set up using the Toyota trans and converter I had mine stalled as low as they could on the stock converter he said it worked out to about 1600rpm. I have not tried it out yet though so no first hand exsperience.

I did bump my idle a bit when I first got the engine and it smoothed out a lot going up 100rpm or so (no tach). No idea how that's changed now with balanced rods.

 

stall as i know it is when the motor wont rev out any higher with the brakes locked. and yes i have seen this in a log skidder with a 4bt (120hp) and Allison 545 after we swapped to a 6bt (195hp). i'm not sure how much power makes how much difference but it is there. i didn't say he should get a lower stall but that it may end up less if he ends up with less power. i dont know if it it makes less of a difference in a automotive application or not. or what i have learned from my experience is whacked and somebody needs to set me strait, it's happened before.

 

I have a 4L80E behind my 4bd1t. It came out of a 6.5 powered suburban, stock stall (whatever that is) and I think it should be fine. My truck isn't finished yet but I think the engines are close in power and torque.

Without going to a custom torque converter the 6.5 converter is the best bet.

 

I plan on pushing this engine to the limit of the stock injection pump. I believe that equates to about 200 hp and 450 ft-lb of torque or somewhere in that neighborhood.

Compound turbo's are in works as well with a limit of 30 psi of boost to begin with.

Adam

 

I think you will easily hit those numbers, Dougal has done a bunch of number crunching and it looks like 250hp and 500+ft/lbs is the limit of the stock pump.

I have a feeling if you go compounds you are easily going to max out the pump.

 

stock 6.2/6.5 gm diesel stall specs are the same for the big block trucks. 1400-1600. from what Ive been told, this is a good stall for these engines. Its what im running, but have yet to form an opinion. Longbow swears by this speed. Another reliable source tells me 1800rpm (stock SBC v8) is ideal, and 1500 is too low.

 

you can stall it higher if you have lower gear or the other way, but not that much

stock stall should be good, 4l80e is the way to go

 

What difference does your gearing make? stall speed is the rpm your transmission puts power to the wheels. I suppose you could theoretically power out of a stall speed that was too low, if you had 7.60 gear ratio vs a 2.00 gear ratio, but to what end? I couldnt imagine any realistic ratio differences would make a difference in stall speed performance.

Someone please feel free to correct me here if Im missing something.

 

2.00 gear with 1000rpm stall vs 2.00gear with 2000stall

second setup will fell less sluggish, but not that much

in that senario higher stall is a bandaid with wrong gear gear.

 

im going to strongly disagree.

Furthermore, there are lots of variables you are leaving out. for one, what is the powerband of this example engine? weight of example vehicle?

6000# truck with an engine with a powerband of 1800-2200, (my jeep with a 4bd1) would suck with a 1000rpm stall. a 2000 rpm stall would be much too high, but would make "power" to the wheels very quickly. the gear ratio really wpuldnt affect it much if at all.

also, the heavier the vehicle, the more powerful the engine, the lower stall you'd want.

 

do you ever drive a car truck with a 2000rpm stall?? its not spinning to 2000rpm and then grab like a manual trans. i have a 3800 rpm in a firebird the only difference compare to a will say a 2000rpm stal is when you put the lock up, engine rpm drop little more.

i think the key is a good torque converter, you can have high stall and still have a tight converter. my point is whith lock up the stall have lil to no effect on cruise, there guys that run 4500+ rpm stall in car (GAS ENGINE) and still have street manners.

so a 2000rpm stall will not be end of the world but still lil too high for nothing

 

do you ever drive a car truck with a 2000rpm stall?? its not spinning to 2000rpm and then grab like a manual trans. i have a 3800 rpm in a firebird the only difference compare to a will say a 2000rpm stal is when you put the lock up, engine rpm drop little more.

i think the key is a good torque converter, you can have high stall and still have a tight converter. my point is whith lock up the stall have lil to no effect on cruise, there guys that run 4500+ rpm stall in car (GAS ENGINE) and still have street manners.

so a 2000rpm stall will not be end of the world but still lil too high for nothing

There is so much wrong in this statement I do not know where to start. So I wont. I dont think you have any idea how a Tq converter works.

 

its not a racecar so anything in the 1300-2000 rpm range will be good.

or find your peak torque, example 2500rpm and put your stall speed there.

i saw a post saying a higer stall mean lesss efficiency, not with a good costum unit with lock up.

we dont talk about 4000+ rpm stall

 

WTF best cruise rpm is 1800 to 2000 rpm.

 

O.K. Sounds like a factory stall from a 6.5 GM diesel will work pretty well. Is there much benefit going with the $600 performance diesel converter over the $200 one I can get from Napa or a local tranny shop?

Also, who has the best tranny converter out there?

Thanks,

Adam

 

precision industries have good unit, servie and warranty. 1 free stall adjustment.

btw guy take time to read the faq page http://converter.com/faqs.htm

if you have the coin go costum but a cleaned stock one from the Junk yard will be good

like i say in an other post my English is not perfect so maybe i dont write things the way i mean to be, but i know i thing a or two about converter and i do my own trannys

 

ok, so in your opinion , putting a used junk yard tc in is just fine? that isnt language barrier, thats a dumb idea.

 

a rebuilt converter isn't just cleaned and painted. its rebuilt. you are getting ripped off.

 

It's torque that changes your stall speed, not hp. So if your torque converter supplier offers a 1600rpm stall converter, then make sure that's 1600rpm at about 500 ft-lbs. Just in case the 1600rpm was for 400ft-lbs and with 500ft-lbs it's more like a 1900rpm stall.

IMO in my limited experience with autos (I intently dislike them) you need a converter to pretty much stop slipping before your lockup engages. Otherwise things just feel wrong.

 

Behind a 4BD1T a 6.5/454 converter should stall around 1600-1700 and a 350 converter will be closer to 1900/2000.

I will disagree with 1600 being the target stall speed for a 3.9 diesel. Different converter designs have different characteristics. The situation to avoid at all cost is running a converter stalled so low that it loads the engine at idle. Most converters in the 1500-1600 range will load the engine at idle. Larger displacement engines with more cylinders will not be impacted by a little idle load, but the 4BD1T or 4BT sure will. The idle quality and off the line performance will suffer.

If you run a 1600 stall speed converter then 1600 will be the max achievable RPM seen at full throttle without the vehicle moving such as pulling away from a stoplight or trying to pull something with a rope/chain. If you run a 2000 stall speed converter you will have a much better overall feel. The acceleration from a standstill will be much better compared to the lower stalled converter. The higher stall speed won't have any downside. The engine will require less fuel for the same acceleration.

With a stall speed around 2000 RPM the converter will still be quite effective from right off idle on up. Light throttle driving will still be responsive, you won't be winding the engine out to get the vehicle to move. It will accelerate fine.

The converter stall speed is too high when the engine revs uncomfortably high without moving such as the case with a stock Dodge diesel converter behind an early 5.9. What's interesting is how that same too high stall for a 5.9 converter is right on for a 4BT or 4BD1T. The 4 cylinders do not have the torque to achieve the same RPM with those converters.

 

Behind a 4BD1T a 6.5/454 converter should stall around 1600-1700 and a 350 converter will be closer to 1900/2000.

I will disagree with 1600 being the target stall speed for a 3.9 diesel. Different converter designs have different characteristics. The situation to avoid at all cost is running a converter stalled so low that it loads the engine at idle. Most converters in the 1500-1600 range will load the engine at idle. Larger displacement engines with more cylinders will not be impacted by a little idle load, but the 4BD1T or 4BT sure will. The idle quality and off the line performance will suffer.

If you run a 1600 stall speed converter then 1600 will be the max achievable RPM seen at full throttle without the vehicle moving such as pulling away from a stoplight or trying to pull something with a rope/chain. If you run a 2000 stall speed converter you will have a much better overall feel. The acceleration from a standstill will be much better compared to the lower stalled converter. The higher stall speed won't have any downside. The engine will require less fuel for the same acceleration.

With a stall speed around 2000 RPM the converter will still be quite effective from right off idle on up. Light throttle driving will still be responsive, you won't be winding the engine out to get the vehicle to move. It will accelerate fine.

The converter stall speed is too high when the engine revs uncomfortably high without moving such as the case with a stock Dodge diesel converter behind an early 5.9. What's interesting is how that same too high stall for a 5.9 converter is right on for a 4BT or 4BD1T. The 4 cylinders do not have the torque to achieve the same RPM with those converters.

A 2000rpm stall on a 4BD1T is ridiculous, it is above peak torque and above peak efficiency. These engines are at their best with a decent turbo pulling from 1500rpm. With a converter that loose you're just throwing all that low end torque away.

Fit a real turbo and you have more than 400 ft-lb from 1500rpm. Acceleration is no problem.

BTW this

The engine will require less fuel for the same acceleration.

is wrong.
With a higher stall converter you will use much more fuel for the same acceleration. The rpm's are higher, the engine efficiency is lower and your losses through the torque converter when running at lower loads are also higher.

 

A 2000 stall speed does not feel sloppy at all. It transfers a lot of power at 1500 RPM and below. It would take full throttle to achieve 2000 RPM, say something around 1/4 throttle will bring the RPM's up to 1500 where the turbo actually does something and the vehicle moves effectively. The converter is not an on/off device.

How the converter behaves is very dependent on it's design. A good converter will not load the engine at idle, will transfer maximum torque at mid throttle positions, but will allow the engine to rev up under full throttle when you need HP to accelerate.

These engines don't make the same off-boost torque that a 6.5 chevy diesel, 7.3 Ford or 5.9 Cummins does. Well tuned, with a modern, conservative turbo the 4 cylinders will make good power at 1500 RPM, but nowhere near what a larger engines does/can.

I would much rather drive a 3.9 diesel converted vehicle with a converter stall speed a little on the high side then one with too low stall speed. If it's too low it's terrible.

 

A 2000 stall speed does not feel sloppy at all. It transfers a lot of power at 1500 RPM and below. It would take full throttle to achieve 2000 RPM, say something around 1/4 throttle will bring the RPM's up to 1500 where the turbo actually does something and the vehicle moves effectively. The converter is not an on/off device.\

Yes, which means it is incapable of delivering maximum torque under 2000rpm. Missing the max torque and max efficiency points of the engine and producing a horrendous amount of heat.

These engines don't make the same off-boost torque that a 6.5 chevy diesel, 7.3 Ford or 5.9 Cummins does. Well tuned, with a modern, conservative turbo the 4 cylinders will make good power at 1500 RPM, but nowhere near what a larger engines does/can.

A 3.9 litre diesel doesn't produce the same off boost torque or peak power as 6-7.3 litre diesels? I'm speechless.

With the right turbo off-boost isn't a problem. I have 10psi and climbing at 1200rpm. I am only over 2000rpm between gear changes on acceleration. All cruise, hill-climbing, towing etc is done at or below 2000rpm.

Do you actually own or drive one of these?

 

Hello Dustin,

Thank you for the advice. Not sure if you have been following my build thread, but the fit and finish on your kit has been excellent to date. Engine is running and I'm looking forward to the next stages of the build.

Adam R.

 

i think this is the key....


A 2000 stall speed does not feel sloppy at all. It transfers a lot of power at 1500 RPM and below. It would take full throttle to achieve 2000 RPM, say something around 1/4 throttle will bring the RPM's up to 1500 where the turbo actually does something and the vehicle moves effectively. The converter is not an on/off device.

How the converter behaves is very dependent on it's design. A good converter will not load the engine at idle, will transfer maximum torque at mid throttle positions, but will allow the engine to rev up under full throttle when you need HP to accelerate.


BUT you need to dyno your engine to find out what will be the best stall speed to choose. those guys can help to build a custom unit with your spec..
http://converter.com/faqs.htm

read the faq maybe it will ring your bell.

 

i think this is the key....

SNIP

http://converter.com/faqs.htm

read the faq maybe it will ring your bell.

second time youve posted this link. Ive read the FAQs, there is nothing in them to support anything you say. What is your point?

 

im very interested to see a dyno sheet with a peak torque that low, i wiil change my project direction.

now i run the stock turbo, the non wastegated t25, i feel the power to be higher, maybe with an other turbo it will have more bottom torque but that low it will vibrate struggle and make noise. dont know how to describe that situation, i saw you claiming it was due to a light flywheel. my car do that now when i load it in overdrive lock up in the 1400-1500rpm. its like struggling, when i go out of lock up but still in OD it goes away and i have a low stall. i use the original of the car and the internet say its a 1300 rpm with the 305cu in chevy v8. i feel its too low for MY set up but the engine will be in that car very long.

 

Pretty much no-one runs the stock turbo, they are sized for a truck running at 3000rpm all day. Bolt on an intercooler with GT2259, TD04HL-19T or HE221, turn the fuel screw and the curves start to look like this:

It is only at max torque below 1600rpm that I get vibration and I suspect most of it is gearbox related. My previous gearbox didn't do it, I'm part way through modifications to try and stop it

 

now my highway speed is +- 1650 rpm at 75 mph, it feel happy there and i do a best of 7.3-7.5 l/km. in theory with better low end torque i can lower my cruise rpm and have better mpg, but its a 4cyl i dont think i will love to be that low. due to the strugling feeling it does lower.