Jeep Straight 6 Long Block in a JT

[PyrPatriot]

Specifically something like the Jeep 4.6L 270 HP EFI Turnkey Engine

Could it fit in the engine bay? and allow for all the other necessary components (including the larger alternator, cooling systems, etc)? I can't find any specifications on dimensions of the 3.6L Pentastar

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[ShadowsPapa]

Specifically something like the Jeep 4.6L 270 HP EFI Turnkey Engine

Could it fit in the engine bay? and allow for all the other necessary components (including the larger alternator, cooling systems, etc)? I can't find any specifications on dimensions of the 3.6L Pentastar

I have three 4.0 engines at home if you need specifics. They are the same dimensions as the 258 - and I have a couple of those, too.

The engine you refer to is based on the 4.0, a "stroker", most likely. They are strong engines, very strong, and crazy torque stroked. Hard to beat them on torque.
I still have my aluminum 4.0 prototype head to put on something - maybe a stroker should be what I do with the third 4.0 I have.

 

[Oilburner]

:DROOL: if the 4.0L in my 2006 LJ craps out one day, I will be looking very hard at a stroker for it. By then they probably won't even be making the little Cummins 2.8 diesel anymore. Some sort of electric conversion will probably be available lol

On a related note, I'm also wondering about a straight 6 in the JT, that 'Tornado' engine seems would be a Tight fit, the 4.0/4.6 gotta be a lot longer...

 

[davetha]

The inline 6 4.0L is probably a decent amount longer than the 3.6L Pentastar as its a V6, not straight 6. You could probably make it work by moving things around and doing some welding. I'm not even sure if the spline count is the same to the transmission. You'd need another ECU etc.. as well. Lots of work.

I have an LS3 in a TJ, its much shorter than the inline 6, but much wider.

 

[Oscar Indy]

I'm gonna be that guy. Why would you waste all that money to go backwards?

 

[ShadowsPapa]

The inline 6 4.0L is probably a decent amount longer than the 3.6L Pentastar as its a V6, not straight 6. You could probably make it work by moving things around and doing some welding. I'm not even sure if the spline count is the same to the transmission. You'd need another ECU etc.. as well. Lots of work.

I have an LS3 in a TJ, its much shorter than the inline 6, but much wider.

What's spline count have to do with anything? You mean input shaft of a standard transmission to the clutch disk?
The 4.0 was used in many vehicles with many configurations. If you are referring to the CLUTCH disk, that's a non-concern - you simply use whatever clutch disk you want to use that matches your transmission input shaft and the pressure plate for the 4.0 pattern (again, they used multiple sizes over the years) - so you could even change flywheels if a stick.
There are wiring kits made, or do what I did - grab the PCM for the engine and build a harness. You can go simple with the "five to live" bit, or like I did- full integration into the host vehicle.
I used the T5 transmission from my car, the 4.0 came from an automatic so I bought a flywheel on eBay, and matched up a pressure plate, clutch disk, and modified the clutch release bearing for the new dimensions.

The length would be the biggest factor, then adapting the bell housing configuration, and the electronics.

 

[ShadowsPapa]

I'm gonna be that guy. Why would you waste all that money to go backwards?

LOL - no kidding.

HOWEVER, if in 5 years I can get my hand on one with a totally trashed engine........ might be fun to put a built 401 into one, or a built 4.0 I have sitting around - something to do with my engines.
But I'd never pull a working viable 3.6 to go that route.

For my 82 the 4.0 was an UPGRADE from the 4.2 - and I did it because I could.

 

[MikeInMo]

I'm gonna be that guy. Why would you waste all that money to go backwards?

I was wondering the same. As much as I like the never say die 4.0 in my '05 LJ, it is no comparison to the 3.6 that was in my '13 JKU.

 

[ShadowsPapa]

I was wondering the same. As much as I like the never say die 4.0 in my '05 LJ, it is no comparison to the 3.6 that was in my '13 JKU.

I'll pit the 1994 ZJ 4.0 in my 82 SX4 against many modern engines of similar size in very low end torque - and I mean right off idle. And I think my ZJ 4.0 could out pull in a tug of war. It's got GUTS. I can accelerate up a 3-4% grade in 4th gear running the engine at about 1500 rpm - accelerate, not lug it.

I'll take my JT's 3.6 for ZIP, scoot outta here really fast, sort of power. It winds up quickly so it's great in traffic.
The 4.0 is a totally different engine, can't compare them at all.
Either way, I'd not take out a 3.6 to drop in a 4.0

I'd likely do to a 3.6 what I did with my 4.0 - I'd build the 3.6 and give it more low end and some more HP in the 2,000-3,000 RPM range.

 

[PyrPatriot]

LOL - no kidding.

HOWEVER, if in 5 years I can get my hand on one with a totally trashed engine........ might be fun to put a built 401 into one, or a built 4.0 I have sitting around - something to do with my engines.
But I'd never pull a working viable 3.6 to go that route.

For my 82 the 4.0 was an UPGRADE from the 4.2 - and I did it because I could.

Exactly. I am thinking like 10-15 years down the road when I hope to start “demodernizing” the thing or buy a junk one to do that to. I love how the JT looks, but I prefer mechanics over sensors and electronics

 

[ShadowsPapa]

I think one with a 500-600 HP 401 would be a blast. And if it was 401 powered, I could race it at our AMC events "must be AMC powered" is the rule. Wagoneers, Jeep pickups (J10 and so on), and more - it's fun to watch them launch and raise the front wheels off the ground.

 

[d k]

wasnt there some combo of using the 258 crank in the 4.0?
I think there was a problem with the squish, so you needed custom rods??

I have three 4.0 engines at home if you need specifics. They are the same dimensions as the 258 - and I have a couple of those, too.

The engine you refer to is based on the 4.0, a "stroker", most likely. They are strong engines, very strong, and crazy torque stroked. Hard to beat them on torque.
I still have my aluminum 4.0 prototype head to put on something - maybe a stroker should be what I do with the third 4.0 I have.

 

[ShadowsPapa]

wasnt there some combo of using the 258 crank in the 4.0?
I think there was a problem with the squish, so you needed custom rods??

A "stroker". No need for custom rods.
There are two versions - the cheap version and a more expensive version with different pistons.

The cheap version - 258 crank, 258 rods (5.875-inch long), and pistons with the stock 4.0L piston pin height (around 1.60 inches.). (short rod version)

The more expensive "long-rod" version - 258 crank, the longer 4.0L rods (6.125-inch) and a shorter piston pin height dimension.

You may be talking quench - you want good quench and turbulence to prevent detonation. If the piston is too deep in the hole, (aside from lower compression) you are more subject to detonation issues, especially with slower RPM engines.

I've grossly over-simplified above - there's a lot more to it, multiple ways of building them, you can get kits, some end up needing higher octane fuel, and so on.
Frankly there are other things you can do with a 4.0 to beef it up a bit - the 4.0 in my SX4 isn't totally stock - .024" shaved off the head, roller rockers, Xtreme 4x4 cam, and I have an experimental prototype head sitting in a box I could swap onto it some day...........

 

[d k]

I remember reading that the ‘short rod’ combo had bad quench and would detonate.
I would be ok with the short rod combo, but would probably want custom pistons with the proper pin height.
There was a company in Mississippi or somewhere that made aluminum heads. But that was a looooong time ago.

A "stroker". No need for custom rods.
There are two versions - the cheap version and a more expensive version with different pistons.

The cheap version - 258 crank, 258 rods (5.875-inch long), and pistons with the stock 4.0L piston pin height (around 1.60 inches.). (short rod version)

The more expensive "long-rod" version - 258 crank, the longer 4.0L rods (6.125-inch) and a shorter piston pin height dimension.

You may be talking quench - you want good quench and turbulence to prevent detonation. If the piston is too deep in the hole, (aside from lower compression) you are more subject to detonation issues, especially with slower RPM engines.

I've grossly over-simplified above - there's a lot more to it, multiple ways of building them, you can get kits, some end up needing higher octane fuel, and so on.
Frankly there are other things you can do with a 4.0 to beef it up a bit - the 4.0 in my SX4 isn't totally stock - .024" shaved off the head, roller rockers, Xtreme 4x4 cam, and I have an experimental prototype head sitting in a box I could swap onto it some day...........

 

[ShadowsPapa]

I remember reading that the ‘short rod’ combo had bad quench and would detonate.
I would be ok with the short rod combo, but would probably want custom pistons with the proper pin height.
There was a company in Mississippi or somewhere that made aluminum heads. But that was a looooong time ago.

I bought a prototype aluminum head at a swap meet last year - all-AMC event, races, show, swap meet, etc. It was one of three made. I know one of the others is on a 4.0 in a Grand Cherokee (ZJ or WJ, can't recall) - the guy was wondering about the head. He bought the Jeep for the engine, I think. Anyway, no one could ID it then after I bought mine, I recognized the pictures of his as being one of the prototypes.
Clifford Research had them made but the heads didn't help the low end and torque like they hopes. The power gain was higher in the RPM band than they wanted so they dropped the project.
When I bought the head it even came in the original Clifford Research box.

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