Higher horses, higher revs & even higher torque, a streetable LJ engine swap - JeepForum.com
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post #1 of 133 Old 06-04-2020, 06:00 PM Thread Starter
toximus
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Higher horses, higher revs & even higher torque, a streetable LJ engine swap

"Never let someone tell you that you dont 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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post #2 of 133 Old 06-04-2020, 06:18 PM Thread Starter
toximus
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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/...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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Building the right way for 37s.
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post #3 of 133 Old 06-04-2020, 06:55 PM
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Hello Mr. Toximus. My name is NashvilleTJ and I will be following your engine build.

Welcome to the forum.

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post #4 of 133 Old 06-04-2020, 08:30 PM Thread Starter
toximus
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Originally Posted by NashvilleTJ View Post
Hello Mr. Toximus. My name is NashvilleTJ and I will be following your engine build.

Welcome to the forum.

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Building the right way for 37s.
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post #5 of 133 Old 06-05-2020, 07:00 AM
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Originally Posted by NashvilleTJ View Post
Hello Mr. Toximus. My name is NashvilleTJ and I will be following your engine build.

Welcome to the forum.

Watch out for this guy. He's going to try to convince you to get a Hemi.
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post #6 of 133 Old 06-05-2020, 10:34 AM
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Im not a pro, but thought I could help you figure out what you want (if you dont already know).

In terms of reliability, Im assuming you mean not breaking down vs longevity. An engine built for power will inherently not last as long. If its 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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post #7 of 133 Old 06-05-2020, 12:00 PM Thread Starter
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Quote:
Originally Posted by gspfunk View Post
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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post #8 of 133 Old 06-05-2020, 12:34 PM
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Quote:
Originally Posted by daddyjeep87 View Post
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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post #9 of 133 Old 06-05-2020, 12:39 PM Thread Starter
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Quote:
Originally Posted by NashvilleTJ View Post
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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post #10 of 133 Old 06-05-2020, 03:39 PM
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Originally Posted by toximus View Post
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 AMGs, Challenger/Charger/WK1 SRT8s, 12-18 JKs) since it can be built and came on the JK. Its 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 TuneJohan).

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 hadnt unlocked the WK PCM when I tuned mine, or Id have gone that route. It has a STEEP learning curve, so a reputable local or online tuner would be best.
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post #11 of 133 Old 06-05-2020, 04:08 PM
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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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post #12 of 133 Old 06-05-2020, 11:27 PM Thread Starter
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Quote:
Originally Posted by gspfunk View Post
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 AMGs, Challenger/Charger/WK1 SRT8s, 12-18 JKs) since it can be built and came on the JK. Its 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 TuneJohan).

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 hadnt unlocked the WK PCM when I tuned mine, or Id 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.

Building the right way for 37s.
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post #13 of 133 Old 06-05-2020, 11:31 PM Thread Starter
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Originally Posted by Pine_Cat View Post
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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post #14 of 133 Old 06-06-2020, 06:24 AM
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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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post #15 of 133 Old 06-06-2020, 09:59 AM
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Originally Posted by CWO_of_Coffee View Post
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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