Chevy Vortec 4200 (Atlas family engine)

I believe it isn't a popular swap mainly because there isn't much aftermarket support for that engine. It is also a fairly complicated engine with DOHC. I don't remember how much HP they make, I want to say it was in the 250-260 range, and being an inline-6 it isn't the easiest packaging-wise compared to an LS 5.3 which can make more power with more aftermarket support. It would be a neat swap though. I dated a girl in college who had a Trailblazer with that engine, and I don't remember it being particularly powerful for a large suv. A Jeep 4.0L built into a stroker is a bolt-in swap and would probably make more power for less money and fabrication.

I haven't seen one in a jeep yet, but it certainly seems viable. Have seen a turbo 2JZ in an XJ.

That aftermarket support situation is changing and these motors can make alot more power than the factory spec. There are some cams for them now also.

Nivlac57 is a good resource and jumping off point. A blog has the measurements.

One problem you'd run into with the 4200 is that it is a front sump and the TJ needs a rear sump because solid axles. This has been solved by sourcing a rear sump atlas 5 cyl oil pan and stretching it.

Option #2.

GoldenGorilla said:

Nivlac57 is a good resource and jumping off point. A blog has the measurements.

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I came to say this.

I've also been pondering the 4200 swap. I currently have a 5.3, and it works a treat, but having a straight 6 back in would be.........wonderful. My biggest issue is how easy the LS fits, that and the existing aftermarket support is overwhelming. That and the 4200 has additional complexities (VVT mostly) that I just don't want to deal with tuning, removing or overly fabricating just to make it work to achieve the same result as what I already have.

I DO however support taking the path less traveled and being "that guy" who didn't listen to the haters and did whatever the hell he felt like doing because it was challenging and fun to boot.

You do you, and I'll help in any way I can.

jeepguy03 said:

I believe it isn't a popular swap mainly because there isn't much aftermarket support for that engine. It is also a fairly complicated engine with DOHC. I don't remember how much HP they make, I want to say it was in the 250-260 range, and being an inline-6 it isn't the easiest packaging-wise compared to an LS 5.3 which can make more power with more aftermarket support. It would be a neat swap though. I dated a girl in college who had a Trailblazer with that engine, and I don't remember it being particularly powerful for a large suv. A Jeep 4.0L built into a stroker is a bolt-in swap and would probably make more power for less money and fabrication.

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There are a couple in TJs. There are several 4200 variants. The later versions were almost 300 hp. The FB 4200 swap group has a requirement that one should at least read and understand some of the Wiki page. https://sites.google.com/view/vorte...lN3ua4oda8sZ_z9o8Q_aem_1mDbLUZt90OeTz5UUNr4ew

mrblaine said:

There are a couple in TJs. There are several 4200 variants. The later versions were almost 300 hp. The FB 4200 swap group has a requirement that one should at least read and understand some of the Wiki page. https://sites.google.com/view/vorte...lN3ua4oda8sZ_z9o8Q_aem_1mDbLUZt90OeTz5UUNr4ew

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Thanks for the link, that's a ton of info. A boosted 4200 would be a really cool swap.

For me, I understand that trying something different is cool and unique. But I always struggle to understand swaps (especially for a TJ) that aren't an LS, Hemi, Magnum, or even SBC. The knowledge, parts, and support already exists. The cost for a swap is going to generally be the same because the fab work required is going to be the same but in many cases you would have something less powerful, more difficult to deal with, or fewer support/mod options. It's not my money though and I'll gladly follow along and read about someone's unique build.

jeepguy03 said:

Thanks for the link, that's a ton of info. A boosted 4200 would be a really cool swap.

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I asked one gent for some info on his TJ swap and apparently I don't meet his high standards since he has failed to acknowledge my existence.

bbaldwin237 said:

For me, I understand that trying something different is cool and unique. But I always struggle to understand swaps (especially for a TJ) that aren't an LS, Hemi, Magnum, or even SBC. The knowledge, parts, and support already exists. The cost for a swap is going to generally be the same because the fab work required is going to be the same but in many cases you would have something less powerful, more difficult to deal with, or fewer support/mod options. It's not my money though and I'll gladly follow along and read about someone's unique build.

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For me, the appeal is the Atlas is all aluminum. It was higher horsepower by a bunch in stock form over the 4.0, torque is outstanding since it peaks about where you'd like it for highway speeds which points to effortless highway driving. Lots of different and easy transmission options.

I also like that the exhaust is already on the correct side and not heating up the intake needlessly.

I also don't like how much work it is for any of your options to build in our normal uptravel. I don't like that the exhaust gets in the way of the control arms unless you want to really expend a ton of effort to make it all play nice together. If I have to work that hard to make basic suspension functional, I lose interest very fast. I'm not ever gonna be engine rich and suspension poor.

mrblaine said:

I asked one gent for some info on his TJ swap and apparently I don't meet his high standards since he has failed to acknowledge my existence.

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I'm sure his TJ probably has the shitty stock brakes on it then.

mrblaine said:

For me, the appeal is the Atlas is all aluminum. It was higher horsepower by a bunch in stock form over the 4.0, torque is outstanding since it peaks about where you'd like it for highway speeds which points to effortless highway driving. Lots of different and easy transmissions options.

I also like that the exhaust is already on the correct side and not heating up the intake needlessly.

I also don't like how much work it is for any of your options to build in our normal uptravel. I don't like that the exhaust gets in the way of the control arms unless you want to really expend a ton of effort to make it all play nice together. If I have to work that hard to make basic suspension functional, I lose interest very fast. I'm not ever gonna be engine rich and suspension poor.

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I can understand all of those points. The weight is about the same as an aluminum LS though which honestly surprised me. I know nothing about their power profiles and have only ever driven one TrailBlazer with the 4.2.

As far as engine rich and suspension poor, the devil's advocate there would be that, more often than not, when someone is swapping an LS they are also on custom axles and suspension not using factory geometry. Of course that isn't always the case by any means and I can see the potential benefits to something like this if keeping that geometry. I guess one would have to weigh the pros and cons with parts availability and aftermarket support. It would also make a big difference if you're doing the engine build and swap yourself.

And again, not my money.

bbaldwin237 said:

As far as engine rich and suspension poor, the devil's advocate there would be that, more often than not, when someone is swapping an LS they are also on custom axles and suspension not using factory geometry. Of course that isn't always the case by any means and I can see the potential benefits to something like this if keeping that geometry. I guess one would have to weigh the pros and cons with parts availability and aftermarket support. It would also make a big difference if you're doing the engine build and swap yourself.

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Voyeurs are always easy to spot.

mrblaine said:

Voyeurs are always easy to spot.

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You're going to have to elaborate on that one? I'm just trying to have a discussion.

Let me clarify, I know the word, I don't understand your context

bbaldwin237 said:

You're going to have to elaborate on that one? I'm just trying to have a discussion.

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As soon as you hop on the devil's advocate coattails to advocate from a position of inexperience, I don't have much use for you. You have exactly zero idea of what it takes to build in normal uptravel or why that even matters, yet, you want to tell me that somehow there are different options since "they are going to be doing it anyway".

mrblaine said:

As soon as you hop on the devil's advocate coattails to advocate from a position of inexperience, I don't have much use for you. You have exactly zero idea of what it takes to build in normal uptravel or why that even matters, yet, you want to tell me that somehow there are different options since "they are going to be doing it anyway".

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Devil's advocate is merely a way to present an opposing view to provoke ideas and generate conversation so the other side can present their case. I never claimed to have the experience, that's where you come in. I've also never claimed to be a fabricator, and many times on here have pointed out that I have to pay someone else to do that type of work. I'm pretty sure you have been involved in LS builds with short, mid, and long arm so I figured you can understand, and explain, how this could be better. I believe @toximus is one running a mid-arm with an LS that you were helpful in. I never tried to "tell you" anything. Merely pointed out that engine swaps are generally part of a more intense overhaul/build.

I never argued with you man, just because others don't have your knowledge doesn't mean they can't have a conversation with you and share opinions. Not trying to set anything off and get blocked, but damn. I'm not asking you to explain suspension geometry. But explaining WHY one engine might benefit suspension design is beneficial to a conversation. Because an LS is slightly shorter (top to bottom) and is shallower/shorter front to back than the 4200. The 4200 is of course narrower, which would impact suspension brackets on the front axle.

Believe it or not, some of us without the knowledge, are open to learning things

bbaldwin237 said:

Devil's advocate is merely a way to present an opposing view

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Fine, what is your opposing view that doesn't revolve around a position of inexperience?

Not sure what the definition of “normal uptravel” is but I’m running short arms with 1.5” of bumpstop with my LS. 1.5” bumpstop doesn’t seem that abnormal to me. I set my bumps based on my shocks, set it on the bumps and built the exhaust. Control arm clearance is a non-issue, front axle yoke has about 1.5” of clearance, so with zero bump stop extension there possibly could be clearance issues but I also didn’t build it for that.

I would highly recommend looking into the GM LV3 or LV1 4.3 V6. They make similar power to a Gen 3 iron block 5.3 but the torque comes in sooner at lower RPM and peak HP/TQ also is at a lower RPM as well. Tune only can net substantial gains, its about 4in shorter than the V8 counterparts, 200lbs less than the stock 4.0, uses transmissions that are easily adaptable to Jeep transfer cases, and a big one is there are TJ engine mounts for these since its the same mounting as a Gen V LT V8 (Novak and Holley have LT mounts available that are based on LS mounts). I also see contractor vans with these engines hit 250k plus miles often.

I’ll be doing this swap in my LJ soon with a 6L80. If you have a cheap core, you can get a NEW engine from GM directly for $2500. I bought a $500 core with harness and all the parts the new engines from GM that are not included.

Abendage said:

Not sure what the definition of “normal uptravel” is but I’m running short arms with 1.5” of bumpstop with my LS. 1.5” bumpstop doesn’t seem that abnormal to me. I set my bumps based on my shocks, set it on the bumps and built the exhaust. Control arm clearance is a non-issue, front axle yoke has about 1.5” of clearance, so with zero bump stop extension there possibly could be clearance issues but I also didn’t build it for that.

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Normal is when I have to trim off the front of the upper control arm mount to keep it off of the radiator hose, and then hard bump it so the joint doesn't smack the AC compressor too hard.