4cyl swap to Inline 6

[littlezeeker]

I Have a 86' Jeep Comanche in it has a 2.5 4cyl motor in it and i would like to put a 4.0 Inline 6 from a Jeep Cherokee in to my truck but I know I will need a swap for it and i would like to keep my 5 speed Transmission if at all possible. Has anyone done this swap before or Know were I may be able to get a swap for this. Thanks

[Geonovast]

This needs to go into the tech section, hopefully a mod will move it for ya.

 

Short answer on your transmission: No.

Long answer on your transmission: Definitely not. You'll need a 5 speed trans from a 4.0.

[littlezeeker]

I Know its a 5 speed standard transmission from a 86' jeep comanche with a 2.5L 4cyl motor. Where Should I look to see the Part Number on My Transmission.

[JeepcoMJ]

I Know its a 5 speed standard transmission from a 86' jeep comanche with a 2.5L 4cyl motor. Where Should I look to see the Part Number on My Transmission.

 

you should not bother looking for the part number on your transmission. IT WILL NOT WORK WITH A 6 CYL 4.0 SWAP!.

 

 

this needs to go in the tech section. you have an ax4 or ax5. you need an ax15 or ba10/5

[littlezeeker]

Ok should the 5 speed from the 4.0 inline 6 fit right in the same as the one i have now.

[Automan2164]

You REALLY REALLY need to work on the post placement.

 

Rob L. :roll:

[tbrand]

you have an ax4 or ax5. you need an ax15 or ba10/5

 

 

It's kind of you to provide the options, but we all know you meant "You need an AX15, period." :D

[xj92]

The ax-4 (4-speed) or ax-5 (5-speed) that is behind your 2.5 isn't even close to being beefy enough to last behind a 4.0L, and the bellhousing pattern doesn't match up to the 4.0L either. If you swap in a 4.0L, you'll have to modify your firewall and the front radiator area of your jeep because it is an '86. The dimensions of an ax-15 are different. It is usually all bolt-in for most Cherokees, but yours might not be because it is an '86 and they didn't have the 4.0L until '87 IIRC. One popular swap is to put in a 3.4, which will mount up to your ax-5. A better option, unless you have a lot of money into the BODY of your XJ, is to simply buy one with a 4.0L/AX-15, then swap everything you want from your cherokee onto the 4.0L one and sell your current one.

[Garvin]

The ax-4 (4-speed) or ax-5 (5-speed) that is behind your 2.5 isn't even close to being beefy enough to last behind a 4.0L, and the bellhousing pattern doesn't match up to the 4.0L either. If you swap in a 4.0L, you'll have to modify your firewall and the front radiator area of your jeep because it is an '86. The dimensions of an ax-15 are different. It is usually all bolt-in for most Cherokees, but yours might not be because it is an '86 and they didn't have the 4.0L until '87 IIRC. One popular swap is to put in a 3.4, which will mount up to your ax-5. A better option, unless you have a lot of money into the BODY of your XJ, is to simply buy one with a 4.0L/AX-15, then swap everything you want from your cherokee onto the 4.0L one and sell your current one.

 

You are correct as the 4.0L will not fit into an '86 MJ. They redesigned the whole engine compartment in '87 to fit the longer 4.0L in there. I've seen GM 3.4L and 3.8L engines swapped in place of the 2.8L but haven't seen too many 4cyl's upgraded. There was an AX-5 behind the 2.8L in mine but that was only cranking out a whole whopping 140hp.

 

I chose to swap in a Chevy 350 instead of fighting with the 4.0L (was looking at putting more power in there so was either going to be a 5.7L V8 or 4.7L stroker). Novak makes adapters to put an AX-15 behind the engine and they make motor mounts to fit, but the motor mounts will have to be slightly modified to fit the '86.

 

I'm not sure exactly what you're planning on doing with this Jeep but you will need an AX-15 5sp manual trans if you intend on going with anything larger than the V6.

[JeepcoMJ]

The ax-4 (4-speed) or ax-5 (5-speed) that is behind your 2.5 isn't even close to being beefy enough to last behind a 4.0L, and the bellhousing pattern doesn't match up to the 4.0L either. If you swap in a 4.0L, you'll have to modify your firewall and the front radiator area of your jeep because it is an '86. The dimensions of an ax-15 are different. It is usually all bolt-in for most Cherokees, but yours might not be because it is an '86 and they didn't have the 4.0L until '87 IIRC. One popular swap is to put in a 3.4, which will mount up to your ax-5. A better option, unless you have a lot of money into the BODY of your XJ, is to simply buy one with a 4.0L/AX-15, then swap everything you want from your cherokee onto the 4.0L one and sell your current one.

 

You are correct as the 4.0L will not fit into an '86 MJ. They redesigned the whole engine compartment in '87 to fit the longer 4.0L in there. I've seen GM 3.4L and 3.8L engines swapped in place of the 2.8L but haven't seen too many 4cyl's upgraded. There was an AX-5 behind the 2.8L in mine but that was only cranking out a whole whopping 140hp.

 

I chose to swap in a Chevy 350 instead of fighting with the 4.0L (was looking at putting more power in there so was either going to be a 5.7L V8 or 4.7L stroker). Novak makes adapters to put an AX-15 behind the engine and they make motor mounts to fit, but the motor mounts will have to be slightly modified to fit the '86.

 

I'm not sure exactly what you're planning on doing with this Jeep but you will need an AX-15 5sp manual trans if you intend on going with anything larger than the V6.

 

 

I bet you haven't seen even 1 3.8 buick swap into one.

 

that said, the only difference in the firewall requires a hammer massage, and the header panel/upper rad supports and front crossmember weld right in from a 4.0l

[littlezeeker]

So What Might be the easiest swap for my 86' comanche and add power for me :dunno:

[Geonovast]

4.0

[jimmy21669]

SBC...lol

[JeepcoMJ]

easiest swap would be a 4.0, or a chevy 3.4.

 

parts are easier to get for the 4.0

[jimmy21669]

My EVENTUAL plan is an SBC or 4.3 with the SM420 Muncie behind it, go with the married NP205 Passenger side drop to a Chevy 10 bolt front.

 

A man can dream....

[Darren]

Not another one.............

[littlezeeker]

Why you Say That?

[Hunter]

So the for 87 you wouldn't have to change the fire wall to put the 4.0 in on a 4 cyl? What about the engine mounts how much would they need to be changed? could you just yank the motor and motor mount from a xj an put it in?

 

Thanks, hunter

[mvusse]

Yes, for an 87 the firewall has already been modified to fit a 4.0. Never compared them closely, but I imagine the engine mounts would need to be changed. I also imagine that part is a bolt in affair.

 

Most of the work would be the front: radiator, radiator support, and all the little pieces that go with it.

 

If you get an 87-90 XJ, you will have everything you need and it should bolt in. This includes the computer, TCM if automatic, and engine bay wiring harness. You will also need to pull the fuel pump assembly from the tank and swap out the 2.5 fuel pump on it for the larger 4.0 one. Don't forget to put a new sock on it at the same time.

 

I would suggest getting an entire XJ. Just like a 4x4 swap this will ensure you will have all the little parts you'd probably forget about otherwise.

[cruiser54]

Either do the GM 3.4 swap or get another Jeep.

[64 Cheyenne]

Yes, for an 87 the firewall has already been modified to fit a 4.0. Never compared them closely, but I imagine the engine mounts would need to be changed. I also imagine that part is a bolt in affair.

 

Most of the work would be the front: radiator, radiator support, and all the little pieces that go with it.

 

If you get an 87-90 XJ, you will have everything you need and it should bolt in. This includes the computer, TCM if automatic, and engine bay wiring harness. You will also need to pull the fuel pump assembly from the tank and swap out the 2.5 fuel pump on it for the larger 4.0 one. Don't forget to put a new sock on it at the same time.

 

I would suggest getting an entire XJ. Just like a 4x4 swap this will ensure you will have all the little parts you'd probably forget about otherwise.

 

 

:agree:

[Hunter]

i was thinking doing the 4x4 conversion at the same time as the 2.5 to 4.0 just buy a hole xj for it.

[mjeff87]

Yes, for an 87 the firewall has already been modified to fit a 4.0. Never compared them closely, but I imagine the engine mounts would need to be changed. I also imagine that part is a bolt in affair.

 

Most of the work would be the front: radiator, radiator support, and all the little pieces that go with it.

 

If you get an 87-90 XJ, you will have everything you need and it should bolt in. This includes the computer, TCM if automatic, and engine bay wiring harness. You will also need to pull the fuel pump assembly from the tank and swap out the 2.5 fuel pump on it for the larger 4.0 one. Don't forget to put a new sock on it at the same time.

 

I would suggest getting an entire XJ. Just like a 4x4 swap this will ensure you will have all the little parts you'd probably forget about otherwise.

 

I did the 4.0 swap on my '87, and ^^^^ is 100% correct. You do need to swap the frame horn engine brackets, the holes are already there in the framerails to accept them. You also need 4.0 motor mounts (the 2.5 ones look the same, but they are not and won't work.) The 4.0 radiator bolts straight into the header panel, but you need the two upper rubber mounts, don't forget to snag them also. I used an '89 wiring harness/ECU that came from an automatic MJ, everything plugged in 100%. If I ever decide to switch to an automatic at some point, all I have to add is the tranny and a TV cable, all the wiring and TCU is already there for me :)

 

Jeff

[a1awind]

Ok so perhaps I had my lines crossed. When people said wiring harness I thought that meant rewiring the whole truck front to back! So all I have to get (as long as it has the c101) is the "under hood" wiring? If so, that works out because I am a novice. And was not looking forward to dropping the dash and yanking the interior. ....may have an 88 donor lined up

[Eagle]

The ECU is under the dashboard, and there are more wires going from the C101 to the 6-cylinder ECU than there are for the 4-cylinder, so you will have to swap the under-dash part of the harness with the ECU.