4.2 to 4.0 stroker and BA10 to AX15 swap - JeepForum.com
 
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post #1 of 9 Old 12-04-2011, 11:35 AM Thread Starter
mdemieville
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4.2 to 4.0 stroker and BA10 to AX15 swap

Hey guys, here is the deal. My 4.2 has 170,000 miles on it and needs rebuilt pretty bad. Valve guides are leaking, rings are getting some blow by, and she has the rear main seal leaking again. I wanna go fuel injection anyway so I'm gonna be doing a 4.0 swap no matter what. I will be getting a running vehicle when its time to do the swap, probably a Cherokee, so I can grab everything at once. I plan to do a rebuild on what ever motor I get anyway so while I have it apart is it worth it to swap in the crank and rods from the 4.2? I know I would have to have the rotating assembly balanced and I'm ok with that. If any one has any experience with the swap please chime in.

At the same time I do the engine swap I plan to rebuild and install a 1991 AX15 trans that I have sitting around here at the house to replace my puke-o trans that's in there now. So my question is this....which pilot bearing will I need if I do the stroker? I know that I will have to change the input shaft on the transfer case and plan on stealing the one out of the cherokee that I get for the swap, but haven't seen much on the pilot bearing. If I remember right the 91 AX15 has a smaller snout and I would need one for the 4.2 crank. Thanks for any help guys.

Mark

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post #2 of 9 Old 12-04-2011, 11:42 AM
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post #3 of 9 Old 12-04-2011, 02:14 PM Thread Starter
mdemieville
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I looked there and didn't see too many people who had gone from the 4.2 to the stroker. Almost everyone went from the 4.0.
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post #4 of 9 Old 12-04-2011, 02:54 PM
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Quote:
Originally Posted by mdemieville View Post
I looked there and didn't see too many people who had gone from the 4.2 to the stroker. Almost everyone went from the 4.0.
There's no differnce except you need to find a computer, wiring, sensors, etc from a 4.0 as well as a complete 4.0 engine that you can build with your 4.2's crank and connecting rods (IIRC).

You end up with the same thing, a 4.0 block with some bigger injectors that holds some 4.2 parts. If I remember from my research correctly, everything from the flywheel back should be the stock stuff from the Cherokee then mated to your axles via whatever driveshafts you desire. You'll have to clock the t-case, you can find more info on this in the AW4 swap threads.

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post #5 of 9 Old 12-04-2011, 03:31 PM
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Originally Posted by mdemieville View Post
I looked there and didn't see too many people who had gone from the 4.2 to the stroker. Almost everyone went from the 4.0.
That`s what you are doing if you get an XJ and rebuild the 4.0 engine and use your 4.2 crank. The XJ FI setup and associated wiring.

Make sure you get the correct pistons so your quench height is 0.

If you plan on using your 4.2 crank/rods and pistons. Don`t bother to build it.
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post #6 of 9 Old 12-04-2011, 04:47 PM Thread Starter
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I guess one of my biggest questions is how much of a power and torque difference is there between the 4.2 and the stroker? If it is minimal I will just EFI the 4.2.
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post #7 of 9 Old 12-04-2011, 04:49 PM
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Originally Posted by mdemieville View Post
I guess one of my biggest questions is how much of a power and torque difference is there between the 4.2 and the stroker? If it is minimal I will just EFI the 4.2.
Its significant. The 4.0 puts out more power than the 4.2 stock to stock and its a decently big jump from the 4.0 numbers.

Take a look at this site:
http://www.jeep4.0performance.4mg.com/photo3.html

He has some "formulas" for different stroker builds with some numbers to go along with them toward the bottom of the page.

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post #8 of 9 Old 12-04-2011, 06:20 PM
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Originally Posted by dillonjm View Post
Its significant. Take a look at this site:
http://www.jeep4.0performance.4mg.com/photo3.html
He has some "formulas" for different stroker builds with some numbers to go along with them toward the bottom of the page.

That`s Dino`s site. He is from the Desert Countries. While he has some good information. The HP/Torque numbers are simply estimates pulled from an ancient computer simulation program. Not proven dyno tests.

I would caution any of the low buck builds. Much of the information is conjecture and/or simply wrong. While the parts will go together you will likely end up with mediocre results.

One of the best articles written lately is the stroker series in JP magazine. Where they take a tired 4.0 and replace it with one of the MOPAR stroker engines directly from Chrysler. Here they give some real world information and driving impressions.

http://www.jpmagazine.com/techarticles/engine/154_1107_weekend_mopar_47_stroker/index.html

http://www.jpmagazine.com/techarticles/engine/154_1111_mopar_stroker_motor_part_2/index.html

http://www.mopar.ca/en/accessories/blockscrateengines.php

The stroker from MOPAR doesn't follow any of Dino`s build recommendations.
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post #9 of 9 Old 12-04-2011, 07:24 PM
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Quote:
Originally Posted by jsawduste View Post
That`s Dino`s site. He is from the Desert Countries. While he has some good information. The HP/Torque numbers are simply estimates pulled from an ancient computer simulation program. Not proven dyno tests.

I would caution any of the low buck builds. Much of the information is conjecture and/or simply wrong. While the parts will go together you will likely end up with mediocre results.

One of the best articles written lately is the stroker series in JP magazine. Where they take a tired 4.0 and replace it with one of the MOPAR stroker engines directly from Chrysler. Here they give some real world information and driving impressions.

http://www.jpmagazine.com/techarticles/engine/154_1107_weekend_mopar_47_stroker/index.html

http://www.jpmagazine.com/techarticles/engine/154_1111_mopar_stroker_motor_part_2/index.html

http://www.mopar.ca/en/accessories/blockscrateengines.php

The stroker from MOPAR doesn't follow any of Dino`s build recommendations.
Interesting read. Thanks for the link.

I've been reading a little bit about stroking a 4.0. I think I'm going to eventually try it once my motor gives up the ghost. It still runs great.

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4.5 stroker , 4.6l stroker , 4.7l stroker , trans swap

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