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Discussion Starter · #1 ·
"Never let someone tell you that you don't need more horsepower. Just stop talking to them, who needs that kind of negativity in their life?"

If you missed the main phase of my build, you can find it over here: High travel, high clearance & high octane, a streetable adventure LJ story. I'm still posting non-engine related build updates over there so if you're interested in that type of thing too I suggest you follow both threads!

Ever since I rode along in some Jeeps desert racing and put the supercharger on my Jeep I've turned into a bit of a horsepower junkie. Because ending an addiction is no fun, my methodology here is to throw the biggest, baddest, strongest engine (that doesn't compromise my main build goals) under the hood of my LJ and not be left with wanting anything more.

Unlike the main phase of my build which I received a lot of direction on from MrBlaine and was able to base my build on many many iterations done before mine, this engine phase of my build I'm going to be upfront that I have little to no clue what I'm doing. Don't tell anyone but the most engine speak I do is smiling and nodding when guys talk about their engine's lift, timing, compression, litres, etc -- yeah, I have little to no clue what any of that means. HP/TQ charts are about as far as I understand. I'm sure as I do this engine swap that there will be things that work well, things that could be done better but aren't worth redoing, and things that need redoing. This is new territory for me.

My goals are:
  • Reliability is priority.
  • Not compromising phase 1 of my build is non-negotiable.
  • Cramming as many ponies under the hood as I can.
  • Torque and HP curves need to work well for my uses and not focus solely on peak horsepower.
 

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Discussion Starter · #2 ·
Here's an overview of the Jeep this engine will be going into. (Full details on my build thread: https://www.jeepforum.com/forum/f22...octane-streetable-adventure-lj-story-4274913/)

  • 37" MTR tires on 17" TrailReady beadlocks.
  • RockJock 60VXR axles geared to 5.38 front and rear with ARB lockers, RCV front shafts, load bolts, and full floating rear.
  • 14" Fox coilovers front and rear with 7" up and 7" down at an equivalent lift height of 4"
  • 105" wheelbase which is ideal for my tire size
  • Savvy mid-arm 3/4 link.
  • Tucked skids
  • All aluminum armor and synthetic winchline to keep weight to a minimum
  • 4860lbs fully loaded.

 

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Hello Mr. Toximus. My name is NashvilleTJ and I will be following your engine build.

Welcome to the forum.

:wink2:
Watch out for this guy. He's going to try to convince you to get a Hemi.
 

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I’m not a pro, but thought I could help you figure out what you want (if you don’t already know).

In terms of reliability, I’m assuming you mean not breaking down vs longevity. An engine built for power will inherently not last as long. If it’s not a DD, that could be decades, though. I would probably go w/ an LS plant based on price and overall ease of finding parts. An aluminum Hemi block will set you back a LOT and that just gets you the block.

Are you starting with a new block/engine, or looking to rebuild a junkyard/used setup? Manual or auto?
 

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Discussion Starter · #7 ·
I'm not a pro, but thought I could help you figure out what you want (if you don't already know).

In terms of reliability, I'm assuming you mean not breaking down vs longevity. An engine built for power will inherently not last as long. If it's not a DD, that could be decades, though. I would probably go w/ an LS plant based on price and overall ease of finding parts. An aluminum Hemi block will set you back a LOT and that just gets you the block.

Are you starting with a new block/engine, or looking to rebuild a junkyard/used setup? Manual or auto?
I don't have anything purchased yet but I am strongly leaning toward an LS.

For reliability I want it to not break down unexpectedly and I want longevity (meaning I don't want to have to rebuild the engine every few years -- ideally it'd last me for the rest of my life, but I understand things don't last forever and I'd accept having to replace it again in 25 years with another engine of the same model that'd swap right in without redoing mounts/exhaust/etc.). I expect to put on ~10k miles per year driving to trails. It's not a DD so I don't mind an increased maintenance schedule if that helps reliability.

Because I know nothing about engine building I think I'll end up with a crate engine. I do feel comfortable bolting on externals like headers, accessory drives, an intake, etc. But I don't want to go further than that -- at least not for my first time.

Definitely an automatic with a good overdrive for on the highway.
 

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Watch out for this guy. He's going to try to convince you to get a Hemi.
What can I say - I despise spark plug wires....

Tox - Would an LS pass smog where you are? I know in a lot of states the transplant engine has to have been offered somewhere in the product line - the reason the Hemi satisfies this is that it was offered in the Jeep Grand Cherokee.
 

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Discussion Starter · #9 ·
What can I say - I despise spark plug wires....

Tox - Would an LS pass smog where you are? I know in a lot of states the transplant engine has to have been offered somewhere in the product line - the reason the Hemi satisfies this is that it was offered in the Jeep Grand Cherokee.
Thankfully I don't have any legality concerns to worry about so I can just focus on what will best fit my needs.
 

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I don't have anything purchased yet but I am strongly leaning toward an LS.

For reliability I want it to not break down unexpectedly and I want longevity (meaning I don't want to have to rebuild the engine every few years -- ideally it'd last me for the rest of my life, but I understand things don't last forever and I'd accept having to replace it again in 25 years with another engine of the same model that'd swap right in without redoing mounts/exhaust/etc.). I expect to put on ~10k miles per year driving to trails. It's not a DD so I don't mind an increased maintenance schedule if that helps reliability.

Because I know nothing about engine building I think I'll end up with a crate engine. I do feel comfortable bolting on externals like headers, accessory drives, an intake, etc. But I don't want to go further than that -- at least not for my first time.

Definitely an automatic with a good overdrive for on the highway.
What kind of power are you pushing now?

I love the 6.1 Hemi in our SRT8, and maintenance is way easier than it was on my TBSS w/ the LS2, but the weight difference in the blocks is pretty significant (~100#'s, IIRC).

For an LS, the 2 most common transmissions are the 4Lxx & 6L80. The 4L60/70 came on the TBSS, trucks, F-body Camaros, etc. and can be built (needs to be built!). The 4L80 is much beefier, but requires a bigger trans tunnel and more space then the 4L60 or 70. The 6L80 gives you 6 forward gears instead of 4 and is strong when built also.

Another option might be the NAG1 (Older Mercedes AMG's, Challenger/Charger/WK1 SRT8's, 12-18 JK's) since it can be built and came on the JK. It's 5 forward gears. A kit like this would make it easier (I know nothing about this specific kit). A lot of JK people complain about the NAG1, but the tune and build make a ton of difference. I just had to get mine rebuilt @78k miles (08 WK1 SRT8, ported heads, Kooks Long Tubes, Corsa Exhaust, DiabloSport CMR Tune-Johan).

As far as longevity, more power (from stock builds) decreases that to some extent. A bigger lift cam wears the valve springs more, as will a higher RPM build. The company from which you buy the setup will be able to tell you more details.

Whatever setup you choose, HP Tuners is the only way to go for tuning. They hadn't unlocked the WK PCM when I tuned mine, or I'd have gone that route. It has a STEEP learning curve, so a reputable local or online tuner would be best.
 
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Why not begin with a stroker? That's the cheapest and simplest option, but you'll get a lot of valuable learning. Will probably gain more general knowledge leveragable to other projects from a stroker than from the more expensive options.

After you've learned a lot from the stroker, you may have satisfied your curiosity.
 

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Discussion Starter · #12 ·
What kind of power are you pushing now?

I love the 6.1 Hemi in our SRT8, and maintenance is way easier than it was on my TBSS w/ the LS2, but the weight difference in the blocks is pretty significant (~100#'s, IIRC).

For an LS, the 2 most common transmissions are the 4Lxx & 6L80. The 4L60/70 came on the TBSS, trucks, F-body Camaros, etc. and can be built (needs to be built!). The 4L80 is much beefier, but requires a bigger trans tunnel and more space then the 4L60 or 70. The 6L80 gives you 6 forward gears instead of 4 and is strong when built also.

Another option might be the NAG1 (Older Mercedes AMG's, Challenger/Charger/WK1 SRT8's, 12-18 JK's) since it can be built and came on the JK. It's 5 forward gears. A kit like this would make it easier (I know nothing about this specific kit). A lot of JK people complain about the NAG1, but the tune and build make a ton of difference. I just had to get mine rebuilt @78k miles (08 WK1 SRT8, ported heads, Kooks Long Tubes, Corsa Exhaust, DiabloSport CMR Tune-Johan).

As far as longevity, more power (from stock builds) decreases that to some extent. A bigger lift cam wears the valve springs more, as will a higher RPM build. The company from which you buy the setup will be able to tell you more details.

Whatever setup you choose, HP Tuners is the only way to go for tuning. They hadn't unlocked the WK PCM when I tuned mine, or I'd have gone that route. It has a STEEP learning curve, so a reputable local or online tuner would be best.
Lots of good info.

Right now I should be making somewhere around 250-260hp at the crank (a stock TJ 4.0L is 190hp).

I've been looking at the 6L80 but I do have concerns if it'll hang too low for my tucked belly. And I don't want to loose ground clearance.
 

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Discussion Starter · #13 ·
Why not begin with a stroker? That's the cheapest and simplest option, but you'll get a lot of valuable learning. Will probably gain more general knowledge leveragable to other projects from a stroker than from the more expensive options.

After you've learned a lot from the stroker, you may have satisfied your curiosity.
My original plan was to build an inline 6 stroker myself and enjoy learning but given that I'm also unhappy with the 2.72:1 transfer case ratio I felt that it was time to consider if I really wanted to stick with the stock TJ inline 6 platform or not.
 

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Really can't go wrong with the LS. Short height compared to most V8's and lightweight. They vary a lot when it comes to displacement but the most common would be the LS1 (5.7L) and LS3's (6.3L). Parts are very cheap and any autozone carries most things you need. I can't speak for the LS3, but the LS1 with just a slightly larger camshaft and some long tubes puts around 450hp crank. The only downside would be the lower end power isn't the best, but it still would be an improvement over the 4.0L I6.
 

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Really can't go wrong with the LS. Short height compared to most V8's and lightweight. They vary a lot when it comes to displacement but the most common would be the LS1 (5.7L) and LS3's (6.3L). Parts are very cheap and any autozone carries most things you need. I can't speak for the LS3, but the LS1 with just a slightly larger camshaft and some long tubes puts around 450hp crank. The only downside would be the lower end power isn't the best, but it still would be an improvement over the 4.0L I6.
I agree. I wasn't sure if the OP was making a ton of power already, but it sounds like a solid LS setup would nearly double the crank HP.

There are a ton of custom cam grinders for the LS, so finding one that can make you a low end torque monster shouldn't be too difficult.

Another option might be building a supercharged 3.7. Since it was the JK engine already, rebuilding a used one for boost might be a lighter/cheaper option.
 

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Discussion Starter · #16 ·
During this dreaming phase I have mulled over many different ideas from the different forums and phone conversations ranging from Hemis which would interface easier with the existing dash electronics, a high horsepower SRT8 Hemi, 1000hp turbo LS, dash ideas, cheap junkyard LS engines, different transmissions, Hellephant engines, exhaust header configurations, various wiring concerns, diesels, turbos, etc etc etc. o_O Somebody even mentioned a '98 Honda Civic 4-banger! :rofl:

To help unmuddle the mixture I got in touch with a guy who does engine swaps for a living and has worked with both the Hemi and LS, he's been kind enough to answer some questions for me and point me in the right direction.

The best advice I received is to do a proven engine swap that's been done before and not be the first to do something. Because reliability and actually getting my Jeep running sounds good to me, this seems to be advice that I'll be following throughout the entire swap even if it means missing out on something new and cool.

From the sounds of it, the LS engine is going to have the best bet of fitting into my build.

All of the Jeep interior stuff will function as long as they're powered up with 12v. The airbags, wipers, lights, turn signal, hvac blower, radio etc do not require the PCM.

If I want the factory gauge cluster to work with an LS then I will need to make a special harness that incorporates the GM side with the Jeep side PCM. However the easiest, most reliable and problem free solution will be aftermarket gauges that will interface directly with the GM ECU.

Even though I will be going with an LS I expect most of what I post about packaging the engine and trans will apply to any high uptravel builds where a high pinion axle housing travels up into the engine bay.
 

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Discussion Starter · #17 ·
Really can't go wrong with the LS. Short height compared to most V8's and lightweight. They vary a lot when it comes to displacement but the most common would be the LS1 (5.7L) and LS3's (6.3L). Parts are very cheap and any autozone carries most things you need. I can't speak for the LS3, but the LS1 with just a slightly larger camshaft and some long tubes puts around 450hp crank. The only downside would be the lower end power isn't the best, but it still would be an improvement over the 4.0L I6.
Local parts availability is certainly nice if a part goes out miles away from home.

With the LS3 it sounds like a ASA cam change can add +95hp.
 

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Discussion Starter · #18 ·
I agree. I wasn't sure if the OP was making a ton of power already, but it sounds like a solid LS setup would nearly double the crank HP.

There are a ton of custom cam grinders for the LS, so finding one that can make you a low end torque monster shouldn't be too difficult.

Another option might be building a supercharged 3.7. Since it was the JK engine already, rebuilding a used one for boost might be a lighter/cheaper option.
I'm going to have to research cams more.

In addition to double the HP and TQ, the LS will also raise redline from 5k to 6k.
 

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Discussion Starter · #19 ·
I made my mind up!

I chose to go with a V8 Chevy LS3 6.2L 495hp crate engine. If I ever want more power I can top it off with a Maggie supercharger to make somewhere around 630hp on pump gas or build up the internals to make more power naturally aspirated. If it's too much power I can replace the hot cam with the regular cam to make 430hp.



How I chose this horsepower is the equation that more horsepower = more better. ...at least up to a point... At some point there is a $/HP wall that's expensive and with cheaper power adding mods you run the risk of pushing the engine too far and causing reliability issues. I also have concerns of the throttle being too touchy for slow speed crawling or accidentally spinning the tires on the highway. When you take into account the power to weight ratio of my Jeep and the power required to rotate the 37" tires I think 495hp will start to balance out nicely. My power to weight ratio will be about 1hp:9lbs. In comparison a stock TJ has a ratio of 1hp:18lbs, a 2dr JL is 1:14, a Ford Raptor is 1:12, a Polaris RZR turbo is 1:11, a sports car or top model Jeep STR8 is in the 1:7 range. With my deep 5.38 gears in the axle I probably won't be winning any 1/4 miles but real world driving should be excellent on road and off road.

I did not go with the 530hp crate engine with the ASA cam because the hp/tq chart shows that more power is created at the higher rpms and not as much at the low end like the 430hp and 495hp crate engines do which isn't ideal for me. The lopey cam sounds awesome with good chop but I don't want to have trouble with a low idle either.

The other runner up I considered is the LSX 454. It has 130hp more than the LS3 I chose at the cost of being 150lbs heavier due to having an iron block. In the end I had concerns that it'd have too much power and act more like an on/off switch than incremental throttle, that would only be fun until the first road trip...

I ended up deciding on the crate engine vs junk yard after looking at various used options and finding that the good low mile stuff went before I could nab it. With the crate engine I won't have to worry about preexisting issues, damaged parts, or having to mix and match the best of different stuff together to make the engine the way I want it. From what I've researched mixing and matching different electronic bits from different models and years can also cause electrical connector confusion and ECU reprogramming. Since I'm not familiar with the LS platform that sounded like more than I am willing to take on. What isn't great about the crate engine is that it's not complete and I'm going to have to figure out what's "missing" and finish off the engine.

The LS3 engine is made from aluminum and weighs approximately 100lbs less than the Jeep 4.0L that's coming out. So that's pretty cool!
 
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