Heavyjunk- I'm also thinking about doing a 5.9L Cummins swap on my truck when the 454 dies or I have the money, which ever comes first I guess. What were some things to look out for when doing that swap? Also, what would you say is the best version of the 5.9L cummins to use on my truck. I would like to put the 03 24V in it, but I don't know what to expect size wise compared to the 12V since its a bit more basic.
Towing question?
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95Suburban
OBS Enthusiast
I know im not heavyjunk but thought i would throw in my two cents.
Size wise they are pretty much the same. Same block for the most part. The biggest problem is fitting an intercooler in the front end if you go that route. I used a 99 24v in mine. You will have to massage the firewall a little if you do not run a body lift. As for wiring, all generations can be wired for a swap application. Mine used 4 wires and a relay.
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Size wise they are pretty much the same. Same block for the most part. The biggest problem is fitting an intercooler in the front end if you go that route. I used a 99 24v in mine. You will have to massage the firewall a little if you do not run a body lift. As for wiring, all generations can be wired for a swap application. Mine used 4 wires and a relay.
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great white
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A diesel gmt400 is a touch easier to convert to a 6 BT than a gasser.
Mostly because the guage cluster runs through standalone sensors and wiring vice through the PCM.
No fuel pump to deal with in the tank, although I'm not completely sure I would trust the 3/8 fuel lines to feed a hotter 6BT with the hammer down.
Diesel trucks are "fly by wire" for throttle pedal, so you'd need a gasser pedal.
Diesel trucks have low stall torque converters than a gasser, but they're still a bit high for a 6bt so you'll end up changing that anyways. If you go 6bt and change the converter, make sure you get a triple disk lockup converter to five it a fighting chance. Billet front section will also help as well as being fully brazed.
Most you can "legally" get for a trailer rating on a gmt400 is 10,000 lbs. It has to be equipped with the 454 and 4.10 gearing for that. That's legally, not what it will actually pull. If you're ever challenged by transport on the rating, they're not going to care what you've done to it. They only care about the factory rating. That's just FYI info.
Even a stock/mild 6bt is over the torque rating for a 4L80E (oem rating 440 crank torque). Treat it nice if you use one or send it out for a round of hardened internals. Stay out of overdrive if towing heavy with a 6BT in front of a 4 l80e. The overdrive section is the weak link in the transmission.
A stock 4l80e will last behind a 6bt, but not like it will behind a 454 or 6.5. My 6.5 has dynoed 446 at the rear wheels (We've rough guessed it about 500 ftlbs crank) and my 448,000 km 4L80E is still alive. But I also have torque management active in my transmission calibration and I drive well aware of the fact I'm on a high mile stocker and well above its rating.
The problem isn't the horsepower for a 4L80e, its the torque. As a transmission builder to build one up for 1000 HP and he say no problem. Ask him to build one for 700-800 ft lbs and he'll laugh at you. Tell him its going into a 7000lb truck and he'll just point you to the door or say your warranty ends when it rolls off the lift....
98/99+ 4L80e's got some good improvemtns, including some revised and hardened internals. Most notably the input shaft.
4L85E is marginally better, but the duramx in the vans are derated/neutered because they have the 4L85E behind them. Its to make the transmission live the warranty period. Those dmax's make roughly what a "hot" 6.5 does....
Mostly because the guage cluster runs through standalone sensors and wiring vice through the PCM.
No fuel pump to deal with in the tank, although I'm not completely sure I would trust the 3/8 fuel lines to feed a hotter 6BT with the hammer down.
Diesel trucks are "fly by wire" for throttle pedal, so you'd need a gasser pedal.
Diesel trucks have low stall torque converters than a gasser, but they're still a bit high for a 6bt so you'll end up changing that anyways. If you go 6bt and change the converter, make sure you get a triple disk lockup converter to five it a fighting chance. Billet front section will also help as well as being fully brazed.
Most you can "legally" get for a trailer rating on a gmt400 is 10,000 lbs. It has to be equipped with the 454 and 4.10 gearing for that. That's legally, not what it will actually pull. If you're ever challenged by transport on the rating, they're not going to care what you've done to it. They only care about the factory rating. That's just FYI info.
Even a stock/mild 6bt is over the torque rating for a 4L80E (oem rating 440 crank torque). Treat it nice if you use one or send it out for a round of hardened internals. Stay out of overdrive if towing heavy with a 6BT in front of a 4 l80e. The overdrive section is the weak link in the transmission.
A stock 4l80e will last behind a 6bt, but not like it will behind a 454 or 6.5. My 6.5 has dynoed 446 at the rear wheels (We've rough guessed it about 500 ftlbs crank) and my 448,000 km 4L80E is still alive. But I also have torque management active in my transmission calibration and I drive well aware of the fact I'm on a high mile stocker and well above its rating.
The problem isn't the horsepower for a 4L80e, its the torque. As a transmission builder to build one up for 1000 HP and he say no problem. Ask him to build one for 700-800 ft lbs and he'll laugh at you. Tell him its going into a 7000lb truck and he'll just point you to the door or say your warranty ends when it rolls off the lift....
98/99+ 4L80e's got some good improvemtns, including some revised and hardened internals. Most notably the input shaft.
4L85E is marginally better, but the duramx in the vans are derated/neutered because they have the 4L85E behind them. Its to make the transmission live the warranty period. Those dmax's make roughly what a "hot" 6.5 does....
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You only lose 50 hp for the drivetrain? Not bad!
great white
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Most wag's are about 10-15% loss for a 4L80E.
The 1000 series Allison is usually WAGd at about 20-25%.
You gain strength, but you pay for it. The dura max, luckily, makes up for the loss.
If true, it Would explain a lot of why my lb7 equipped friends can't seem to pull away from my old IDI rattler....
Would you happen to know what a nv4500 ratings are, and if I'm not mistaken, it'd have less parasitic loss as well, correct?
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Yes less than an auto
great white
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Dunno.
Of note is my quoted figures for the automatics is a wag (wild ass guess). That's info that most manufacturers just don't let out or don't bother testing.
Those are generally accepted numbers for those autos and my experience with the 4L80e dyno runs tend to be more or less consistent with them.
As a rule, autos have more loss than standards.
It has to do with autos spinning more mass, running the pump and torque converter losses.
Some of this is regained through torque multiplication in the converter, but it can't over come the basics physics of the situation....
schwarze_crewcab
OBS Enthusiast
If you buy a gasser, buy a big block. don't even waste your time with a 350.
Crummins
I'm Awesome
There are a couple of myths here:
On converting a gasser (96 and up)... it makes sense to leave the computer since the computer runs the A/C and some other things so all you do is run the stock sending units for the gauges and they work just fine.
6.5 Diesels and 454's were equipped with the exact same torque converter. I have been running my stock (now with 120k on it) torque converter behind a Cummins and it works fine. The stall is a touch high but there is hardly any turbo lag because of it. Every place I have talked to that has done Cummins / Diesel converters recommend about 1700 or 1800 stall since that is when the turbo lights off. I personally think this is high but I don't do that for a living so I can't argue with it. Triple disc is unnecessary unless you are pushing 1000 torque (but couldn't hurt, except your wallet)
My 4L80E is 100% bone stock and has been holding up behind a moderately pumped up Cummins (93 engine with larger injectors, BD Super B turbo, upgraded intercooler to 1994 Dodge, 4" exhaust, fuel pin and pump mods). Most of those miles were put on towing an 8k travel trailer. It works great and the trans temp never gets above 150 when driving down the road. I ALWAYS run it in Overdrive and it hits lockup very soon after it shifts into OD. It works great and has a ton of power when that converter locks up.
There is my experience. My buddy, who is a transmission guy, is pretty amazed that the 4L80E is still holding on strong. He expected it to last about 1000 miles behind the Cummins and when it broke we would make whatever broke stronger -- as well as other stuff -- and rebuild it.
