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Engine upgrade planning. Are there smog legal manifolds for an LS/SBC swap?

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I'm doing some planning on my MJ project.  I've looked at a few options.  I could do a TDI swap  but that isn't quite the direction I want to go.  Other diesels are remote possibilities but they all will involve a ton of custom work.  I've looked into doing a 5.9 magnum swap.  Also a 5.0 (or 5.8) Ford.  Again, too much custom fabrication.  I briefly looked at a couple of other V8 options but they're even harder to find parts for and require a lot of fabrication.


What I keep coming back to are two different options:


First is to just go with a 4.6 stroker.  It's by far the easiest swap since it's a bolt in.  A well built stroker provides plenty of power to do serious rock crawling.  The wiring is a non-issue since it stays stock.  I can get some basic upgrades to the AW4 so it will hold up to the power just fine.  And the build will give me plenty of opportunity to run serious transmission cooling to keep it going.


But a small block Chevy 350 or LS would be pretty sweet.  Plenty of power and there's tons of off-the-shelf parts to make it just short of a bolt in swap.  The biggest problem I'm running into is what to do about a smog legal exhaust.


And before anyone tells me to move, that isn't an option.  I am where the job is and I have to pass smog regulations.  That isn't going to change.


The biggest issue with the SBC/LS swap is exhaust manifolds.  I know it's a dumb law because it's just routing exhaust out of the engine and it doesn't actually have any significant effect on what comes out of the tail pipe.  But the bureaucrats are what they are.  Colorado follows California emissions rules so I need either factory manifolds or headers with a CARB EO number.  Trying to find ones that fit in an MJ engine bay is challenging to say the least.  I've seen a few people talk about it on various forums but I can't find any definitive answers.  I've read the Novak swap guide backwards and forwards.  All they have to say is to use the headers they sell but they won't pass emissions.


Does anyone know of any CARB approved headers that will fit?  Maybe factory manifolds but from what car/truck?


It's likely I'll just punt and do a stroker.  That at least would pass the visual and I can use factory exhaust components to stay compliant.  But if I can find a good manifold for a V8 swap I'd prefer to go that route.


Any help would be appreciated.



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That's a possibility.  But it's decidedly inconvenient.


I have found that exhaust manifolds from a TPI 350 from the 80's may have manifolds I could make work.  Benefit of that engine is the low end torque from the long runners and it's a swap that fewer people do while still being a small block chevy.  And I could easily drop in a 383 stroker to make some really good torque.


Still, I'm likely to end up with a stroker.  There's no way to tell it's a stroker from the outside.  I can use factory exhaust which is smog legal.  And with a mild to moderate cam it makes decent power while still passing emissions sniff tests.  So I get more power without the hassle of fighting smog referees.

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I'm sure you've done some online searching on this, I will eventually LS swap my MJ and found some info stating that the GM F body exhaust manifolds may work, check that out... 

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4 minutes ago, zomeizter said:

I'm sure you've done some online searching on this, I will eventually LS swap my MJ and found some info stating that the GM F body exhaust manifolds may work, check that out... 

I've heard that.  But I've also heard they don't fit without modification. 

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