Dodge Cummins 12 valve ???

[leopold]

love the thought of Diesel Jeep... a friend of mine offered me a 1996 Dodge cummins 12 valve with a p-pump. is this a good engine for a swap, or should i save my pennies and go 4BT...im a total newbie, so please be gentle :) it would be going into a 1985 Grand Wagoneer.

[blkwarrior]

If you are getting it I would not wait for the 4BT. I would drop the six in ASAP :D .

[BotterbrodtGE]

Meh cummings 12 valve is worth nothing but I'm willing to take it off your hands for you as a favor ;)

But in all seriousness
Definitely an awesome motor, I'd assume you'd have to/ should stiffen the front frame due to the weight and build up the front springs as well

But definitely cool, I'd suspect everyone would prefer a 6 cyl Cummings over the 4 if they had a choice. But more experienced guys will chime in soon.

Good Luck :thumbsup:

And welcome from Southern New Jersey

[billyrb]

the p-pump (94-98.5) and ve-pump (89-93) engines are great engines, and are the simplest of the 6bt's. The common rail engines (98.5 and up) DO make more power, but are computer controlled and are a little more involved to convert to. I have a p-pump engine in my F350 and should have it running soon, but it was stupid simple to install, and only requires 3 wires and a fuel line to run.

Plus, parts for the P-pump and VE-pump engines are incredibly cheap and easy to install. A rebuilt CP3 injection pump from a common rail can run $1,500-3,000. A rebuilt P-pump injection pump is around $400-$700 (just an example). And, you can make killer power on the P-pump engines with $500 in injectors, $40 in fuel rail and $10 in governor springs, with just a few hours of your time turning wrenches. And, you can also add on a larger turbo for even more power should you desire.

The 4bt's are great and are smaller, but they command a premium as everyone with smaller vehicles / imports are buying them up, as the 6bt is too big / heavy for them. If it were me, I'd get the 6bt and rock n roll.

[poolmike]

It all depends on what your desires are. If you can score a 12 valve for cheap or free....GET IT! A 4bt is an excellent motor, very efficient. However, a 6bt will hardly work itself to move a FSJ. If it was my decision, it would be 12 valve.....coming from a guy with an extra 12 valve looking for a Wagoneer with a blown engine :fsj:

[lobie]

I'd say go for the 12v but that's because I'm doing one.

Do a little searching on here on both. They both require fab work. The 12v may also involve some axle upgrades. It's up to you but do some reading to understand what ur getting into.

[leopold]

i'd like thank everyone who chimed in on this thread. i'm gonna go with the 12 valve. i got about 2k coming back from the gov , so ill use that cash for install and upgrades. once again thanks. but i will be back with more stupid questions later :D

[Resbum]

I agree with everything everyone has said, so far. Here's some other things to consider.

Width- Is not an issue at all.
Height- Is not an issue with some thought.
Length- Will be very tight depending on how you do it. A lot of people have done it without notching the firewall. I'm notching mine 2" because of how I did it.
Frame- Give serious thought to strengthening it. I personally think it's a mandatory upgrade.
Heater core- Will most likely try and share the same space as the turbo if your '85 is the same as my '70 pickup.
Front springs- The 6BT weighs twice as much (1050lbs) as any V8 Jeep ever put in a truck. I'm using the springs out of a 1991 Dodge that came with a 6BT.
Drivetrain- A 6BT can make CRAZY torque at low RPM's. At the least, you want Dana 60's in the front and rear. Transfer case- get a strong one. Transmission- Because of the low end torque 6BT's can eat up an automatic. The right manual transmission survive better. I'm going with an automatic, but it was the single most expensive part of my build to make it somewhat 6BT proof.

As a life long gasoline burning wrench turner I had to really change my thinking when it came to the 6BT. With it I think in the terms of "torque", not "HP". A 6BT making 250HP can easily be cranking out +600lbs/ft torque.

I say go for it with great gusto!!!!:thumbsup: Just be ready for it.

Resbum

[billyrb]

on the heater core issue, if you use the later model exhaust manifold, it tucks the turbo under the exhaust and down tight near the block. That should give a good bit more clearance. Also, if you have the fiberglass heater core case (and not the metal one), you should install the exhaust manifold AFTER the engine is in place.

[leopold]

i just went and checked the motor out and it seemed like it ran well. as for the heater core, i never even thought about that as an issue, thanks for the eye opening facts everyone has awakened me to. i am concerned about drive shaft angles more than anything else. once again, i truly appreciate all the knowledge everyone has given, and will post some pix soon :)

[Resbum]

on the heater core issue, if you use the later model exhaust manifold, it tucks the turbo under the exhaust and down tight near the block. That should give a good bit more clearance. Also, if you have the fiberglass heater core case (and not the metal one), you should install the exhaust manifold AFTER the engine is in place.

Thanks Ryan for this good tidbit of info. I wonder how I've missed it. Do you by any chance have a picture of it you can share?

... i am concerned about drive shaft angles more than anything else. once again, i truly appreciate all the knowledge everyone has given, and will post some pix soon :)
My truck has a 132" wheelbase. I'm running a 47RH with an NP205. My front and rear driveshafts will both be around 47" long. I'm going to run 1350 CV's on the transfer case ends and 1410 U-joints at the axle ends. The primary reason I'm running 1410 u-joints isn't strength, but because they can handle slightly greater angles than the 1350's. I'm not talking huge angles. More like 12-14 degrees on a daily driver.
Resbum

[billyrb]

I think I have a picture on my other computer, I'll see if I can dig it up tomorrow

[billyrb]

This is what was on my p-pump engine (94-98.5). Not sure what years this style was stock, as mine came from an industrial application. But, you can see the manifold turned town for a tighter-to-the-block fit.

http://i301.photobucket.com/albums/nn78/billyrb/IMAG1576.jpg

[The PIG Smith]

Frame- Give serious thought to strengthening it. I personally think it's a mandatory upgrade.
To me, this a highly debatable issue, of which IMHO, there is no wrong answer.
However, some feel very passionate about one side of this discussion or other: strengthen the frame or it's good enough.

I have struggled with this very topic for my future 6BT swap project and asked this very question:
http://www.ifsja.org/forums/vb/showthread.php?t=121320

Tell me, how do you plan to strengthen your stock OE FSJ frame?

[Resbum]

You answer this yourself with my reasons in the thread you refer to in the above post, when answering whether a frame should be strengthened for a 6.2L swap.
IMHO, No, you would not.

First, the GM 6.2L Diesel is about750# fully dressed compared to the Cummins 6BT which is about 1200# dry.

You are correct, the torque from a6.2L is nowhere near that of a Cummins 6BT.

The 6.2L is about the same size andonly slightly heavier than a small block Chevy.

So, if the FSJ frame can handle thesize, weight and power from a hot SBC, then the 6.2L is not a problem.

The issue as I understand it is theFSJ frame would not hold up to the excessive weight and the torque from aCummins 6BT

To me, this a highly debatable issue, of which IMHO, there is no wrong answer.
Let me make clear I agree with you 100% and that’s why I phrased my comment the way I did. Remember this thread asked specifically about a 6BT swap.

Frame- Give serious thought to strengthening it. I personally think it's a mandatory upgrade.

Resbum
Ultimately, for me, it came down to the fact that I’m using an engine that weighs twice as much, and can easily make twice the torque, of any engine Jeep ever engineered this frame for.

How did I strengthen mine? I started by climbing under a friend’s M715 and taking 15 pictures.

From there I used 1/4 inch plate for mounting the trans crossmember into the frame.
http://img442.imageshack.us/img442/5230/20111016164529.jpg (http://imageshack.us/photo/my-images/442/20111016164529.jpg/)

I then boxed it in from there back to the next factory crossmember with 3/16 inch plate
http://img38.imageshack.us/img38/4892/20111202153727.jpg (http://imageshack.us/photo/my-images/38/20111202153727.jpg/)

And 3/16 inch plate was welded to the inside of the frame rails from the new motor mounts to the front of the frame.
http://img267.imageshack.us/img267/2155/20111202153636.jpg (http://imageshack.us/photo/my-images/267/20111202153636.jpg/)

I also boxed it in between the rear spring mounts and bed mounts with 3/16 inch plate
http://img196.imageshack.us/img196/8324/20111202153713.jpg (http://imageshack.us/photo/my-images/196/20111202153713.jpg/)

http://img138.imageshack.us/img138/1963/20111202153748.jpg (http://imageshack.us/photo/my-images/138/20111202153748.jpg/)

Again, I agree that this is a highly debatable topic.

Personally, after studying everything, I came to the conclusion that with a 6BT swap the frame should be strengthened.

That's just my opinion. Resbum

[Resbum]

This is what was on my p-pump engine (94-98.5). Not sure what years this style was stock, as mine came from an industrial application. But, you can see the manifold turned town for a tighter-to-the-block fit.

http://i301.photobucket.com/albums/nn78/billyrb/IMAG1576.jpg

Thanks Ryan. I'm not sure if this manifold would work on my engine. The OEM automatic trans fluid heat exchanger is where the turbo is tucked into with this manifold.

Resbum

[COLOFIREMAN]

I see you've alreadty made your mind up but the 6BT is the way to go. I have a 4bt thats going in one of my fleet of FSJ's......JM2C....a 4BT is a great motor for a GW or a Cherokee....but if I was building a truck, it would be a 6BT all the way:thumbsup:

[leopold]

Resbum... thank you so much for the photos.. i get back tomorrow from australia and begin the change over.. i bought a few mags in Australia....there are so many diesels there and all are fitted for off road use. i wish the USA would finally hop on the wagon ( WAGGY) with diesels stock in JEEPS :fsj: