2.5 I4 -> 2.8 V6 swap questions

sureshot007

sureshot007

NAXJA Forum User
Location
Kenmore, NY
I have an 86 MJ with the TBI 2.5 4 cylinder with an AX4 tranny (it's rwd). I have a MPFI GM 2.8 V6 from a camaro. I am just trying to get an idea of what I need to facilitate this swap.

- Motor Mounts (I'm just making solid mounts)
- I have the ecu and wiring harness from the camaro
- Power Steering Pump? can I use the pump that's on there or do I have to use the Jeep one?
- Clutch? the clutch discs look to be the same size and teeth count, but will the pressure plate bolt up to a camaro flywheel?
- Flywheel? see clutch
- Gauge Cluster? It's not really crucial that the gauge cluster work, but it would be nice.

Anyone have experience with this? I know the MJ came with the v6 as an option, but it was an older carb'd one.

Also, please don't ask why I'm doing this swap, it's for staying in the class I'm in for rally. Also, don't suggest I swap a different motor (already planning a v8 for next season, this just has to get me through this season). Thank you for helping and staying on topic :)
 
You'd have better luck if this got moved to modtech.

How are you going to mount the camaro's v6 to the ax4? Are you going to do a transmission swap too? The bellhousing of the ax-4 won't mount to the new v6. I'll bet the transmission input shaft won't be accepted by the new engine either.

Motor Mounts - When you say 'solid' I hope you don't mean that you're going to hard mount the engine to the frame...

My guess is that the pressure plate won't even come close to bolting up to the camaro flywheel.

Getting the gauge cluster to work will depend on how much work you want to put into the wiring harness.

None of the parts that Jeep released a XJ or MJ with will be compatible with a chevy motor... Have you actually looked into parts compatibility or the adapters that Novak sells yet? I'd be surprised if there's anything on the market for this application.

Are there any other optional engine swaps to stay in the same class? This would be one hell of a project to use for just one season.
 
yikes! Don't put a 2.8 in, it's way less reliable than the 4cyl you blew up!

Put in a 3.4 and tell them it's a 2.8 :shhh:
 
youre more than halfway through this season, just drop another stock 4 banger in it. itll bolt and plug in, itll be cheap, and itll work.

what exactly are the rules in RA about motors and swaps? i'm not 100% familiar with it (or even the class youre running fwiw)
 
asp said:
How are you going to mount the camaro's v6 to the ax4? Are you going to do a transmission swap too? The bellhousing of the ax-4 won't mount to the new v6. I'll bet the transmission input shaft won't be accepted by the new engine either.
Click to expand...

The MJ/XJ with the V6 came with an AX5.

asp said:
Motor Mounts - When you say 'solid' I hope you don't mean that you're going to hard mount the engine to the frame...
Click to expand...

Yes.

asp said:
My guess is that the pressure plate won't even come close to bolting up to the camaro flywheel.
Click to expand...

This was a concern of mine. But I should be able to use a camaro pressure plate if the discs are the same dimensions.

asp said:
Getting the gauge cluster to work will depend on how much work you want to put into the wiring harness.
Click to expand...

Exactly why it isn't a big deal and I probably won't worry about it. I have a speedometer/odometer built into the rally computer, and a giant tach already. Plus it's the cluster with warning lights instead of gauges, so it's pretty useless anyway.

asp said:
None of the parts that Jeep released a XJ or MJ with will be compatible with a chevy motor...
Click to expand...

Except for the part about the XJ/MJ used a GM 2.8 V6 in the mid 80s.

asp said:
Are there any other optional engine swaps to stay in the same class? This would be one hell of a project to use for just one season.
Click to expand...

This is a topic that has been beaten to death, so I don't feel like rehashing it.
 
Yeah, I was mostly joking on that... cheating while racing isn't cool.

The 2.8 (at least the versions used in XJs/MJs) was known for oil starvation issues and the resulting sudden improvement in crankcase ventilation.
 
sureshot007 said:
The MJ/XJ with the V6 came with an AX5.

Yes.

This was a concern of mine. But I should be able to use a camaro pressure plate if the discs are the same dimensions.

Exactly why it isn't a big deal and I probably won't worry about it. I have a speedometer/odometer built into the rally computer, and a giant tach already. Plus it's the cluster with warning lights instead of gauges, so it's pretty useless anyway.

Except for the part about the XJ/MJ used a GM 2.8 V6 in the mid 80s.

This is a topic that has been beaten to death, so I don't feel like rehashing it.
Click to expand...
Running the AX-5 is a fine idea, but make sure it bolts up to the new engine.

No. Don't do that. Get some poly bushings and some 1/4" plates and make your own motor mounts. Hard mounting it is a terrible idea.

If the discs are the same dimensions but the bolt patterns aren't the same you're still up sh!t creek.

I didn't realize the v6 they used was a GM engine, that's good to know. Good luck finding parts....

I'm not trying to tell you to do something you obviously don't want to, just trying to help you decide whether or not this is the best thing for you to do. It seems like an awful lot of work for a bandaid.
 
sureshot007 said:
I would have....if I was road racing...
Click to expand...

i'm aware youre rallying. i'm aware youre in your first year, where you cant run a 4wd class. i lived at my buddy's shop in highland for a year while i was at school, just figured you should keep it simple til you up a class, bc the sport isnt cheap and i'm aware.

oh, and my buddy outpaced 4wd cars, in higher classes... in a first gen RX7. in the snow. his current car is a mkIV golf. a good car out of the box is a good car out of the box, doesnt matter what the surface,
 
93XJLI said:
i'm aware youre rallying. i'm aware youre in your first year, where you cant run a 4wd class. i lived at my buddy's shop in highland for a year while i was at school, just figured you should keep it simple til you up a class, bc the sport isnt cheap and i'm aware.

oh, and my buddy outpaced 4wd cars, in higher classes... in a first gen RX7. in the snow. his current car is a mkIV golf. a good car out of the box is a good car out of the box, doesnt matter what the surface,
Click to expand...

I'm going into my 3rd season actually. Who's your buddy?
 
Peak stresses have no where to go but to break something. Poly helps.
 
sureshot007 said:
Why is solid mounting a bad idea on a race car?
Click to expand...
It will rattle the sheet metal in the front unibody apart. Ever heard of unibody cracks? They're usually caused by lots of stress due to being off camber but I could see this causing it. I bet it could crack the block eventually too...
 
asp said:
It will rattle the sheet metal in the front unibody apart. Ever heard of unibody cracks? They're usually caused by lots of stress due to being off camber but I could see this causing it. I bet it could crack the block eventually too...
Click to expand...

These are "eventually" things...not something I am going to worry about since it will only see less than 500 miles next year, and then it's getting retired for a new chassis with a v8. Besides, I need to worry more about crashing into a tree or rolling off a cliff.
 
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