my friend DD'd a 4BT TJ with an AX15 on 4.10s and 33s for 2 years. no issues. 30 mpg highway.

 

How about a GM 3500 turbo swap? Same thing as the old 3.1s but they have a forged crank. Pretty popular swap with most of the GM 60degreev6 crowd.

 

I'm going to bump an old thread with a new engine. I've been given a '90 Pontiac Bonneville with a Buick 3800 (3.8l) engine in it. I have researched and have found out it uses the same bellhousing (link https://en.wikipedia.org/wiki/List_o...metric_pattern ) the GM Metric Pattern, as my old 2.5l. The car ran when it was parked, just ran down - busted headlights, taillights, windshield, etc... The engine (engine compartment) is clean leading me to believe it was somewhat taken care. I get the engine and all associated wiring ECM and will send the rest to the crusher.

Now for the question - Has anyone done this engine swap before? It seems mechanically simple - as the bellhousing I have will bolt right up. I'll just have to swap out all the old wiring with the new stuff... I'm not looking forward to that.

 

Honestly i wouldn't use a 4bt in any jeep.Its 750lbs which is 200 more then the stock 4.0,And the price of them has sky rocketed lately.A junkyard one is 2k a running one is 3k.On swapping in a 3800 i would be more worried about the motor mounts then anything else.And make sure the engine runs and do a compression test on it before you buy it.

 

The 3800 is in the car sitting by my shop. Don't need to buy it, I own it. And I'm not worried about the motor mounts - more worried about the electrical end of it. Trying to piece together the best way to approach this. The AX5 is weak (or so they say) and a stronger tranny might be better than to over power and break the AX5. I haven't started on extracting the engine out of the Bonneville yet as my shop has my daughter's Jeep Liberty CRD in it with the engine out. It seems the mechanic her husband hired to change the timing belt doesn't know diesels and he put it back together with the intake cam one tooth out of time. But that is another story.

 

Take your time and pull the engines wiring harness first and mark every plug so when you put it in the jeep you have a idea where everything goes.The jeep side should be easier but you still gotta wire it some.

 

I know Jeep used the same bell pattern as the 60 degree engines and even though the engine you have is a 90 degree engine, it uses the 60 degree bolt pattern...weird.

Did the GM engines use a GM computer or is it some kind of bastardized GM/Jeep combo? If the engine runs off the GM computer, you can probably just swap the entire harness over and only have to splice in where you need your gauges at.

 

Yeah, Was thinking on tagging each side of a plug/socket connection. Then it won't be a guessing game - just match up matching tags. Like starter 1, starter 2 - even though you know the big wire goes to the big bolt. I used colored cable ties on my daughter's Liberty.

I have the engine and a supposed weak transmission, so I'm researching other trannys that could replace the AX5. An AX15 or NV3550 are holding my attention at this point. Just gotta find the right bellhousing to go in the middle.

currently...

AMC 2.5L ---> jeep OEM bellhousing ---> AX5 ---> NP207

1st choice
BUICK 3800 ---> ??? bellhousing ---> NV3550 ---> NP231
2nd choice
BUICK 3800 ---> ??? bellhousing ---> AX15 ---> NP231

This is just an outline at this point - still collecting pieces. And reading and re-reading multiple forums. Next summer's project.

Just read in another forum that a 96-00 Dodge Dakota 2.5L bellhousing supports the AX15.
BUICK 3800 ---> DAKOTA bellhousing ---> AX15 ---> NP231

Anyone else heard of this before?

 

I haven't looked under the hood of the donor Bonneville too much as my attention has been elsewhere. Now that the mechanic is buying a 'new' engine for her Liberty I have had some extra time. I have no problem splicing wires - I did that for a phone company for many, many years. Just smaller wires - or even smaller glass (fiber optic).

 

I believe the gm v6 in the jeeps used a carb,Gm didn't go efi tell 87 and by then the v6s was gone from the jeeps.From 81-86 gm used a crappy computerized carb and dizzy that really did nothing.

 

so I may be in the market soon for a swap ....I have a buddy who did the LM7 swap and loves it ..... I have a line on the LH6 aluminum block for next to nothing that will be waiting for me whenever I decide to do this and Novak has all the powertrain know how to make sure it will work .... its for a 99 XJ sport on its way out and when it finally quits im thinking full restore/build .. Any thoughts or suggestions?

 

the 1985 GMC S-15 indeed had an awful carb- I replaced it with a great weber. The 1986 S15 had TBI.