Comanche History

[500 MJ]

I ran across this today, pretty interesting... http://www.allpar.com/trucks/jeep/comanche.html

[jbhill]

good read.

[702_MJ]

:agree:

[Eagle]

Not bad. Only found two major errors.

 

It is disappointing, though, to see another "source" perpetuating the myth that the 4.0L engine was based on the 2.5L when the fact is the 2.5L was based on the 4.2L I6, which was based on the preceding 3.8L I6. Makes you wonder where these people get their information.

[aemsee]

Not bad. Only found two major errors.

 

It is disappointing, though, to see another "source" perpetuating the myth that the 4.0L engine was based on the 2.5L when the fact is the 2.5L was based on the 4.2L I6, which was based on the preceding 3.8L I6. Makes you wonder where these people get their information.

 

Not sure I follow your thought on this one Eagle. The 2.5 did come before the 4.0. Or do you mean that a more correct lineage would be the 4.0 based on the 4.2? I just look at them all being in the same family. Damn good engines. Too bad they didn't bother to do more development on the 2.5. I think there is untapped potential there.

[Eagle]

Not bad. Only found two major errors.

 

It is disappointing, though, to see another "source" perpetuating the myth that the 4.0L engine was based on the 2.5L when the fact is the 2.5L was based on the 4.2L I6, which was based on the preceding 3.8L I6. Makes you wonder where these people get their information.

 

Not sure I follow your thought on this one Eagle. The 2.5 did come before the 4.0. Or do you mean that a more correct lineage would be the 4.0 based on the 4.2? I just look at them all being in the same family. Damn good engines. Too bad they didn't bother to do more development on the 2.5. I think there is untapped potential there.

The 2.5L engine wasn't designed out of thin air. My racing friend was service manager at the dealership our family used back when the Cherokee came out. He said back in 1984 that the 2.5L engine was nothing but a 258 (4.2L) with the middle two cylinders taken out, and that's true. The same I6 "family" dates to 1964, when AMC first introduced it as a 232 c.i.d. (3.8L). Two years later they added a de-stroked version that displaced 199 cubes, and then somewhere in the 70s they increased the stroke and bumped the displacement to 258 cubic inches. That's the same 4.2L engine that was used in the Wrangler right up through 1990, and that's the engine that the 4.0L was derived from. As was the 2.5L.

 

Doesn't matter that the 2.5L came a couple of years before the 4.0L -- that doesn't mean the 4.0L was based on it.

[jpnjim]

It's pretty subjective.

 

2.5L's were based on the existing AMC L6 (of course).

In that development, they redesigned alot of parts, for more durability, ligher weight, improved the ports, combustion chambers, etc, etc.

 

When they finally got around to freshening up the L6's design, they used the information they gathered, and parts they developed for the 2.5L.

 

Does that mean the 4.0L was based on the 2.5L. No, or mostly no I guess.

 

Alpar usually has pretty good info, but parts of this article seem misleading.

They metion the Chrysler rear axle, but I don't know of any MJ that ever got one of those.

They don't mention the AMC M20 used in 86' MJ's tho.

Standard towing capacity was 1,400 pounds (1,475 pounds starting in 1987), using a Dana 35 or Chrysler axle.

I'd guess they meant 'load' capacity, and not towing capacity here.

 

Bob Sheaves also wrote: “In 1992, the Dodge Dakota trucks campaigned in the Mickey Thompson Stadium Truck series won the championship from Toyota by a wide margin. In reality, these two trucks were the previous year's Comanches with the Dakota sheetmetal. The trusty race modified 4.0 Jeep engines were even used instead of the Chrysler 3.9 V6s!”

I found this part very interesting, I never heard that before (wonder if it's true).