Swap Questions: 6.2/6.5 vs Cummins 4BT

[ThePIGSmith]

I am studying the idea of swapping in a Diesel in my 1986 Jeep Grand Wagoneer.

My original thoughts were for a 6.2/6.5, but I've been reading where the Cummings 4BT can get over 30 miles per gallon of fuel.
Also, the 4BT can accept all the performance upgrades that the Dodge 6BT can take (larger injectors, maybe IP) and can also take lots of boost.
So it's stock 120 HP can be 'turned up' between 160 and 200, depending how deep one's wallet is.

My thoughts to make a Full Size Jeep get 30+ MPG and have lots of grace and style while doing it.

I would like to hear opinions of why the 6.2/6.5 would be a better swap or not.
Or how the Cummins 4BT would be a better swap candidate or not.

[gmctd]

If that Wagoneer has a seperate steel frame, the only problem will be the heighth of the Cummins engine - will it fit between the hood and the front suspension.

A ring for the Chevy clutch housing was a standard option, so you can use the NV4500 5-speed and other GM

A ring for the Chrysler bolt pattern is also available, so you can use the NV4500 or Torqueflyte trans from the big Dodge\Cummins setup.

[ThePIGSmith]

If that Wagoneer has a seperate steel frame, the only problem will be the heighth of the Cummins engine - will it fit between the hood and the front suspension.

A ring for the Chevy clutch housing was a standard option, so you can use the NV4500 5-speed and other GM

A ring for the Chrysler bolt pattern is also available, so you can use the NV4500 or Torqueflyte trans from the big Dodge\Cummins setup.


All Full Sized Jeeps (Wagoneers, the original Cherokee, J Series Truck) have a seperate steel frame
Height is not a problem.

A few other folks have performed this swap with good results.
The Cummins 4BT fits FSJ's engine bay well.
On the other hand, the Cummins 6BT is a wee bit to long.

Other folks have performed 6.2 and 6.5T swaps into Full Sized Jeeps.

My point of making this post was to gather opinons and more info about why a 6.2/6.5T would or would not make a better swap than the Cummins 4BT.

It seems as if the PROS and CONS on both engines are about equal.
Maybe I will make a more complete PROS and CONS list and post it here.

[Adam King]

Take a look at this link, this guy put a 4BT in a early Bronco, he has some pretty good info.

https://home.comcast.net/~jcmiley/


-AFK

[JeepSJ]

And I'm in the final stages of a 6.5TD into my 87 Grand Wag. It is tight, but it fits. The 4bt will be easier as it is narrower than the 6.5 and will eliminate some of the space issues that I had, but the 4bt is tall and may require a suspension lift, a body lift or transmission tunnel mods.

Figure that the 6.2/6.5 goes in with the same mounts and adapters as a Chevy V8, so that part is easier. Width is an issue though and you have to run a hydoboost brake setup and if you run a turbo then you lose the AC/Heater box that is under the hood.

The 4bt is not as long or as wide, so it should fit a little better, but there is the issue of height and weight. The 4BT does wiegh more than the 6.2/6.5. My 6.5 long block with IP weighed in at 650 (and that included the shipping crate), whereas I have heard the 4bt long block weighs about 750. No one makes any conversion mounts, so you would have to fab those.

See you over on IFSJA...(DieselSJ over there).

[ThePIGSmith]

Hello again JeepSJ/DieselSJ

I've followed your progress of your rig.
You comments in a recent post on the IFSJA (International Full Jeep Association) that had you to do over, that you would have gone with the 4BT.
Also, another new IFSJA member in the same post indicated he done this conversion several time and buddy get 34 MPG consistently.

Yes, I agree that a 6.2/6.5T would easier it install be using standard Chevy Mounting brackets.
But, if I were harvest a 4BT from a Chevy P30 van, I feel that some of those frame side mounts could be easily modified to work on the FSJ frame.

No matter is I would go with a 6.2/6.5 or a 4BT, everything else would be the same.
For example, I would use a Chevy tranny on either engine, probably a built and diesel prepped 700R4.

So, my goal is trying to determine the performance differences between the 6.2/6.5T and a tweaked 4BT.
On paper, they look similar, HP and Torque, just that the 4BT get better fuel economy.
Maybe a person could tweak a 6.2/6.5 for more power, but it looks as if the Cummins could take more mods, thus maybe more power?

So, I need to complete a PROS / CONS list and post it here.

I am not trying to start a flame war, by talking about Cummins in a GM forum, just trying to get the most information as I am considering this project.

[Craig M]

Interesting that the 4 cylinder Cummins is heavier than the 8 cylinder 6.2. I would not have guessed that!

[JeepSJ]

Yeah, if I do it again there is an 80% chance that I would do the 4BT. I think if you built a 4BT and a 6.5 to put out 500ft/lbs, the 4BT would be more reliable and could be done for less $$. Don't get me wrong - there are a lot of guys here with that kind of power in their 6.5, and they are reliable. But there are also guys here who have spent big $$ on things like splayed main caps and such.

Rumor has it that I just might have my eye out for a full-size Cherokee (though if I towed one home before we got settled in Phoenix I would probably end up living in it).

One of the guys over on JeepsUnlimited just picked up a very nice Grand Wag AND a FritoLay van. You know where that one is going.

Do the 4BT.

[poolmike]

I have my fresh built 6.2 installed in my M715. Installation and motor mounts are a snap. I used a GM NV4500 and a divorced NP205. It should be interesting when the rest of the truck is re-assembled.