Cummins 6BT swap in a V2500 Suburban?

[Mitch F]

I'd love to get all of your guy's input on putting a cummins in my V25000 89 Suburban. The truck has been in my family for many years now, barely put on 2k miles a year it's only used in the summer time at our lake house (still has less than 100k miles on it). Although i am now in college and my Ex daiy driver was a 2002 1500 suburban. So I have now inherited the truck from my father and am driving it around college. What I would like to do is put a cummins in it clean up the rust, get better fuel milage and hopefullt be able to pull our large boat (12,000lbs) at our lake house. I know that doing this swap on an 89 suburban is kind of hard as it doesnt have the IFS of the later models so theres some clearencing of the front subfram that needs to be done and the truck will either have to be lifted to clear the final valve cover or the firewall will have to 'massaged' a little.

So my questions for you guys;
1. Are there better solutions for what i am trying to achieve other than buying another truck?

2. Do you think that swapping a cummins will allow me to pull something that heavy? (I know the truck wil physically carry the boat, we've done it before but the old 350 chevy won't pull it up any hills)

3. Will the stock drive train suffice? It's currently got a 4l80e and im not sure what differential is.

And please feel free to add your thoughts below if theres anything else I should be thinking about.

You must be registered for see images attach

You must be registered for see images attach

 

[Overland Suburban]

Hey Mitch I'm getting ready to do the same thing to my 89 Suburban. This is what I've learned so far.

Your suburban likely has a 14 bolt rear and that will work fine but the front axle if stock is a 10 bolt and that WON'T hold up to a 1200 lb Cummins. A Dana 60 is a direct bolt in swap and that's what you want. Also will need different front springs I haven't figured out what I'm going to use yet but my thoughts are to bolt an A Bomb on the front of my square and go with the longest ford springs I can find that are for the ford deisel trucks. Long springs ride nice and a Cummins will ride like **** with the WRONG springs.

Personally I am going to use a 90 rotary pump non intercooled Cummins for simplicity and it's all the power I need. I also love the way they start the in a sixth of a revolution Everytime. I won't have to fab any intercooler stuff and it will be cleaner under the hood.

I believe your 4l80e will bolt right up to a 12 valve Cummins but not 100% on that!

Last of all your going to get a lot of is it worth it comments and just 350 tbi it and the fuel you save won't pay and on and on and so forth. My take is put a Cummins in it and take your time to do a nice clean professional job. In ten more years when someone comes along and gives you $50,000 for a 12 valve square body burb you can tell everyone who didn't have the vision of what these will be worth I toldja so.

Summit Racing has a Engine mount kit or you can build your own. I'm going to have a local fab shop who has already done a few do mine for me.

There's obviously a lot I missed but hey I thought I would jump in and give you some moral support

Tracy

 

[Shorty81]

Nice looking Chevrolet !! Personally I would not transplant a non GM engine. If anything I would bolt up a big block. No matter what you do you are not going to get very good gas mileage.

 

[Frankenchevy]

I believe your 4l80e will bolt right up to a 12 valve Cummins but not 100% on that!

I’m pretty sure you need an adapter plate. The th400/6bt/4bt combo was a common sight in bread vans, frito lay vans and many other larger step vans and should have the adapter. If I ever did this swap, I’d pick up a running used bread van for 2-3k and have most of what’s necessary.

 

[Overland Suburban]

Nice looking Chevrolet !! Personally I would not transplant a non GM engine. If anything I would bolt up a big block. No matter what you do you are not going to get very good gas mileage.

A 12 valve Cummins will get 20 mpg in a suburban

 

[1987 GMC Jimmy]

A 12 valve Cummins will get 20 mpg in a suburban

Good advice above. If I was doing this swap, I’d also go for an 89-91 to keep it VE44 w/o intercooler. I wouldn’t go past ‘93. It’s still a fairly powerful motor, and you can tune on it a little bit to improve the stock specs. This version is the true nexus of simplicity and a torquemonster powerplant. IMO, Dodge gradually ruined a great motor by overcomplicating it.

He’d need an adapter plate, and a mild 6bbt is the ceiling for what a 4L80E can handle. What I’m seeing says 440 ft/lbs of torque. That’s flirting with disaster in my book, especially if the OP wants a more electronic rendition of the plant or just wants to get the most out of the early setup as possible, in which case I could see the motor eclipse the transmission’s torque rating. I’d look into getting a 4L85E if keeping it GM is a must, or I’d look into making a Toqueflite 47RH or RE work, and that way you’d only have to figure out how to control OD and lockup with the former and no adapter plate either.

My brother has a 24V 6bbt tuned liberally to roll coal and has straight pipes with a turndown exit near the rear pumpkin. That thing’s been nothing but trouble with the injection pump, lift pump, RMS, clutch and throwout bearing, the myriad of electronics, and the actual body/interior of the truck. The double cardan joint snapped in the front shaft a while ago so it’s a kinda lifted in the front/squatting in the back 2wd. But at least you can hear the small p*nis coming from miles away!

 

[hunters628]

1993-1996 are the best years for a Cummins engine. 93 is the last year of the VE pump. Which don’t get me wrong is a great pump. I have a VE pump in my truck. You can easily tune them to 300hp. 94 is the first year of the P7100 pump, the best of the cummins injection pumps. These are the pumps guys use to build 1000+ hp pull trucks. Almost infinitely tunable. The internals are pretty tough, good castings, and overall a reliable motor. If I was going to buy a cummins for a swap I would get a 94-96 engine. Still fully mechanical and at the peak of their performance. You can run these engines with 1 wire. 97-98 still has the P pump but it starts getting more involved. 99 the VP pump came out and that was the end of mechanical. 93-96 are all 12v intercooled engines and about as simple as it gets. Mine fires up first crank every time no matter if it’s 10 below or 100 outside. Something to be said about that.

 

[skysurfer]

It's currently got a 4l80e and im not sure what differential is.

I’m curious how it came to have a 4l80e? Did you kill the original trans or just upgrade?

 

[R3500lowsluttruck]

I’m pretty sure you need an adapter plate. The th400/6bt/4bt combo was a common sight in bread vans, frito lay vans and many other larger step vans and should have the adapter. If I ever did this swap, I’d pick up a running used bread van for 2-3k and have most of what’s necessary.

what is this land of everything I need? years and body type? Where would i even see one for sale?

 

[Frankenchevy]

Search CL for bread van or step van. Upon further research they almost all come with a 4bt. The 6bt makes too much torque for a typical auto trans that’s easily swappable into a square auto. Th400 and 4l80 won’t live long behind a 6bt.

In other words, unless you want the 4bt; a better donor might be a 6bt equipped box truck which may come with an Allison attached. The Allison will require a body lift or trans tunnel/firewall mods from what I’ve read.

Unfortunately, a 6bt by itself is pretty pricey in the used market.

 

[R3500lowsluttruck]

Search CL for bread van or step van. Upon further research they almost all come with a 4bt. The 6bt makes too much torque for a typical auto trans that’s easily swappable into a square auto. Th400 and 4l80 won’t live long behind a 6bt.

In other words, unless you want the 4bt; a better donor might be a 6bt equipped box truck which may come with an Allison attached. The Allison will require a body lift or trans tunnel/firewall mods from what I’ve read.

Unfortunately, a 6bt by itself is pretty pricey in the used market.

What RWD auto trans can handle a 6bt? Also any help. I am currently building a replacement wiring harness for my truck and 454. Where would one go about trying to locate all the necessary electric connections to run a 6bt? That will help me build a sub harness for when the swap happens.

 

[Frankenchevy]

What RWD auto trans can handle a 6bt? Also any help. I am currently building a replacement wiring harness for my truck and 454. Where would one go about trying to locate all the necessary electric connections to run a 6bt? That will help me build a sub harness for when the swap happens.

An Allison, 47RH, Aisin etc.