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Old 12-08-2012, 12:09 PM   #1
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rebuild 4.2 vs v8

My 90 yj is about ready for a engine upgrade. I'm torn between turning the 4.2 inline6 into a stroker with EFI or dropping a small v8 into it. as with everything budget is a concern. any thoughts? stock transfercase with SYE and double caden front drive shaft, 4.56 gearing, 5sp, 4"lift on 33s.


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Old 12-08-2012, 02:08 PM   #2
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Well if your here in CA then you have smog to worry about. Doing a 4.2 short block with a 4.0 head and a small cam then EFI makes the most sense. If your crawling with it then it really makes sense. A good 4.2 is a torque monster down low. The V8 would require a lot more work. Mounts, tuning, exhaust, cats,adapters,etc. But if you did it smog legal then you would have some hot YJ on your hands. OH YEAH welcome to the forum.
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Old 12-10-2012, 02:47 PM   #3
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Thanks Bob. That was my thought too. Just nice to get a second opinion.
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Old 12-11-2012, 12:00 AM   #4
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Seeing as how I only put about 3k mi on my rig last year it'll probably be forever before I need a new engine but this is what I want when I do.

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Old 12-12-2012, 10:09 PM   #5
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Baja that would be awsome and mayber scary with my heavy foot.

I agree with Gunner. The 4.2 is great on low end torque. and will cost less in the long run for the rebuild. I am planning on doing pretty much the same thing. Hadn't thought abotut he 4.0 head, was just planning on the Howell system. California make mods such a pain.

Good luck on your rebuild.
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Old 12-12-2012, 11:03 PM   #6
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The 5.3 rocks. And the aluminum 5.3 is golden. I think if I was doing open desert or dunes I would go with the 5.3 or 5.7 Hemi. Otherwise I think a 4.2 or 4.6 is the hot ticket for a low rev crawler. Might not be fast but it has instant low end torque. So far I don't think I have had to go past 2500 rpm to do any of the obstacles on Holcomb creek or Calico. Hardly makes sense to do a V8 and lose the 1000 to 2500 torque curve for 290hp at 5500 rpm. I'm just never there. And I can do 80 on the freeway as is.
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Old 12-13-2012, 11:48 PM   #7
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Quote:
Originally Posted by castman2 View Post
Baja that would be awsome and mayber scary with my heavy foot.
I hear ya. I'm pretty light on the throttle myself but that could change with a V8. To be honest in all the places I've wheeled, challenging or not, I've not really ever felt hat I could use more power other than when I'm boogieing across the desert, like Gunner mentioned.

That said IF I was at a crossroads I might take the 5.3 plunge. Much more work to do for me before I go down that path though.

Good luck!

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