Transplant? Modify? Restore?

[V]

If you have an old Jeep that you would like to keep running for another 10 to 20 years and it is in need of an engine, ECU and wiring refresh now, what would you do?

 

1. Transplant a modern used engine petrol or diesel?
2. Transplant a modern 'crate motor'?
3. Modify the 4.0L to make it a 4.6L stroker up to 300bhp?
4. Restore the 4.0L with a blue printed rebuild?
5. Something else, perhaps electric?

[V]

After thinking about this more overnight, I have expanded the list:

1. Transplant a 21st century used engine petrol or diesel (4.0L Toyota 1UZ-FE V8, GM LS1 V8, Jeep 2.8 CRD)?
2. Transplant a brand new 2023 crate motor (6.2L GM LS3, 2.3L Ford Mustang EcoBoost, Cummins R2.8)?
3. Rebuild and modify the 4.0L to make it a 4.6L stroker up to 300bhp?
4. Rebuild and modify the 4.0L normally aspirated up to 250bhp?
5. Rebuild and modify the 4.0L forced induction up to 300bhp?
6. Restore the 4.0L with a blue printed rebuild up to 200bhp?
7. Full battery electric conversion ($50K+)?
8. Custom hybrid EV conversion on the 4.0L (flywheel motor)

I did consider transplanting a used hybrid powertrain but these are all likely to be based on a front wheel drive transaxle and not rear wheel drive 2wd or 4wd.

[UKTJ]

Gut response would be option 1 or option 2, putting a V8 in just instinctively feels like the right answer.  But then I don't really know what it would take, so maybe that would be a mistake.

[digger]

Have to be a V8 or a blower for me!! 

I just wish I still had the energy!  We could have two then! 

UKTJ, It would take a lot of hard work, but it would be worth it, eventually!

Edited February 4 by digger

[stewart]

Go The Toyota V8 Diesel 1VD-FTV engine ? 

 

Electric with the batteries option is still in it's infancy so i would be reluctant to go that route ! 

[V]

The 1VD-FTV looks very interesting, although the weight is shocking in comparison to the Jeep 4.0L .

 

Jeep 4.0L i6 weighs 219kg

Toyota 4.0L 1UZ-FE petrol V8 weighs 165kg

Toyota 4.5L 1VD-FTV diesel V8 weighs 372kg

 

[AlexK]

Have been thinking about this recently.

 

While every part of my being is screaming "V8!" the cost of petrol is only going to go one way. The idea of dragging an older Jeep into the realms of modern-car fuel efficiency really appeals to me.

 

First thought was to use a modern crate unit. Ford is the obvious candidate with a range of units, but realistically only the 2.3 Ecoboost fits the bill, and I'm really not a fan.

 

The Cummins is appealing and it's certainly well-proven. @stewart's idea of the 1VD-FTV is even more appealing, and that's a hell of a unit. But the petrol/diesel fuel price differential looks set to continue, so unless it's achieving unheard of levels of fuel efficiency, it could still prove an expensive option to run.

 

My current thought is to look at the idea of a 2.0 GME probably from a crashed JL or other FCA-made donor. Good power, reasonable economy and emissions, although peak torque's a little high up and to my ears (apologies to all JL owners) it sounds like a bag of spanners in a washing machine at idle. Could potentially find a way to team it up with the eTorque front belt mild hybrid set-up if you wanted to go all out on the fuel savings, although would be technically challenging as that set-up didn't make it to Europe I believe.

 

Tempting to also take it with the 850RE 8-speed transmission, which is actually a decent ZF unit. Potential fly in the ointment here is that this combo is probably pretty long - unlikely to get it in a TJ, for example.

 

For a left-field idea, it might be tempting to see what happens with the new straight-six Hurricane unit.

 

Of course, the problem with all of this is that we're talking about using an electronically complex current-gen engine, so integration would be a bitch. Old tech has many, many advantages.

 

What level of efficiency do you think you could get out of an economy-minded BP'ed 4.0L?

[V]

18 hours ago, digger said:

Have to be a V8 or a blower for me!!

I have started comparing options that fit into the above list on the following criteria:

• Overall cost
• Project complexity
• Reliability
• UK sourced components
• Improved fuel economy over the original 4.0L
• Future component supply
• Future fuel availability
• Enjoyment
• Minimal authoritarian problems

I am leaning towards #5. Rebuilding the 4.0L with some modifications to make it better suited to being supercharged.

[V]

I am very interested in the Edelbrock alloy cylinder head, but I would be willing to try a ported 7120 head first. The Edelbrock is a bolt-on fixed cost. Reworking an old Jeep head costs money even if you do it yourself. Doing it properly requires a flow bench and there are engineers in the UK with the skills and equipment. Chasing flow improvements is an ever increasing cost so at some point, the cost of the Edelbrock makes more sense.

 

 

[V]

1 hour ago, AlexK said:

Tempting to also take it with the 850RE 8-speed transmission, which is actually a decent ZF unit.

I had not considered a transmission upgrade. I wonder if there are efficiency gains to be had with a more modern automatic transmission.

[UKTJ]

One of the guys that posts on the US TJ forum I frequent has now started selling a bolt on turbo kit for 4.0l TJs.  I have had a could of exchanges with him and sadly it would not work with RHD due to engine bay packaging differences on things like steering.  Even if it could be made to work, no idea how this stacks up against other options for your criteria.

 

 

Edited February 5 by UKTJ

[V]

I found this web page about fuel economy gains for the ZF 8-speed.

 

A ZF 8-speed I have had problems with in the past could not easily be resolved by swapping in a used transmission. A lot of the electronics are submerged in the transmission fluid but I vital part of the software sits outside in the engine management. The transmission and engine are digitally entwined with encryption keys. In my case BMW had to authorise any transmission swap. If a stand alone transmission controller is not available for a ZF 8-speed then a transplant would require paired engine and transmission from a single donor vehicle. There is no valid reason to use encryption pairing between an engine and transmission unless you are a car manufacturer that wishes to control (restrict) the supply of used car parts.

[V]

12 minutes ago, UKTJ said:

One of the guys that posts on the US TJ forum I frequent has now started selling a bolt on turbo kit for 4.0l TJs.

 

That's an interesting kit.

 

It may be easier to turbo a RHD TJ because the steering isn't in the way on the left side. A turbo on the right hand side would create a lot of heat near the ignition components and may experience more turbo lag with a longer exhaust turbine feed than one with the turbo closer to the exhaust valves.

 

I do like turbos, but for the type of slow speed off road driving I enjoy, a supercharger is a better fit for me.

[V]

I found a standalone controller from HTG Tuning for the ZF 8-speed auto and another called a Turbo Lamik.

I didn't realise that the ZF 8HP70 was used in the Grand Cherokee SRT8, as the Chrysler Torqueflite 8.

I also didn't know the JL Wrangler and JT Gladiator has ZF 8HP50.

Finding a variant that accepts a transfer case bolted to the output end is the key.

 

Coupled to a 4.0L Jeep i6, I don't think I need more than a 8HP45. Even one with 6psi boost from an Eaton M90. 

A possible common UK source for a ZF 8HP70 would be the 2012 Range Rover Sport. No idea if this massive transmission will fit an AW4 transmission tunnel but it would be lightly stressed off road.

 

 

 

[V]

An 8 speed transmission conversion done in Australia.

 

 

[V]

Doing more research, I have found that the Grand Cherokee WK2 has a 850RE transmission which is a license built ZF 8HP50. Does anyone know if the 850RE can bolt up to a NV231, NV241 or NV242 transfer case?

[AlexK]

18 hours ago, V said:

I had not considered a transmission upgrade. I wonder if there are efficiency gains to be had with a more modern automatic transmission.

 

I would expect so, and could be substantial. That ZF design had a number of changes throughout its life, many of which were cited as having sizeable economy gains.

 

10 hours ago, V said:

Doing more research, I have found that the Grand Cherokee WK2 has a 850RE transmission which is a license built ZF 8HP50. Does anyone know if the 850RE can bolt up to a NV231, NV241 or NV242 transfer case?

 

Yes, 850RE is used with the NV241 in US-spec JL Sport and Sahara models, and the NV241OR in Rubicon. Euro-spec JLs all have the MP3022, though, same as the US JL with optional Selec-Trac.

[V]

1 hour ago, AlexK said:

Yes, 850RE is used with the NV241 in US-spec JL Sport and Sahara models

Do you know if the 850RE and NV241 uses the same size 23-spline output/input as the XJ, ZJ, TJ, WJ, KJ and JK?

[V]

I suppose if it's not 23-spline the transfer case input gear could be swapped for a 23-spline model from an earlier NV241.

[stewart]

check this out https://jeepspeedshop.com/8-speed-swap/

[AlexK]

Stewart wins the internet for today.

 

There's a TJ with a Hemi and an 8-speed on their YT channel. I fear we may not see V for a few days while he watches every video.

[V]

2 hours ago, stewart said:

check this out https://jeepspeedshop.com/8-speed-swap/

 

I will have to do some more research on this kit. They are not using the mechatronics controller in the kit so at this point I assume it is using updated firmware in the JK ECU so is likely matched specifically to a JK ECU.

 

The TCM-2800 manual throws up an interesting point about the controller needing to know if it is in low ratio. My plan is to install a transfer case doubler on this build, so I will need 2 or perhaps 3 low ratio configs

1. 2.72:1
2. 2.72:1 and 7.4:1 or
3. 2.72:1, 4:1 and 10.88:1

I guess the standalone controller that can do this already or one with support willing to do custom mods will be the one for me.

[V]

2 hours ago, AlexK said:

I fear we may not see V for a few days while he watches every video.

The new inverter welder I just bought just died on the first use so it's possible.

[V]

In order to go further with this I need to start stripping out options from the list that I think are now unlikely candidates. They may still be relevant to someone else so I will explain why I am discounting them.

 

List item #1

I think I can drop the idea of transplanting a used engine for the following reasons:

• Mechanical complexity - engine mounts, exhausts, radiator, inconvenient ancillary device locations
• Electronic complexity and reliability - Interfacing instruments. Is a 20 year old used ECU any less risky than using a 30 year old ECU?
• No advantage on future parts availability changing from one obsolete engine to another type of obsolete engine
• Marginal or non-existent fuel economy gains over the Jeep 4.0L
• A bit of a gamble choosing a CRD diesel for longevity - no ability to run home-made diesel fuel reliably

Reasons to reconsider #1 later on:

• The last opportunity to enjoy owning a V8
• An 8-speed transmission upgrade that comes with an already matched engine
• A bargain engine too good to turn down

 

List item #2

The best proven fuel economy gains and emission reductions can be had with the newest design engines. However, I am dropping them from my list because:

• Modern engines are not designed for longevity. Planned obsolescence and over use of plastic components in their design that have long term UV stability, chemical resistance and thermal resistance issues making replacement more likely and incurring a risk of future parts availability.
• A lot of modern engines have been designed specifically for production line assembly with little or no consideration given to component replacement within the engine bay
• Complexity demanded by emission regulations but at a higher risk of unreliability
• Dependency on OEM tools and software
• The highest cost - Pushes back the break even point on fuel economy savings over the 4.0L into years

 

List item #7

I have been interested in an EV off roader for 20 years, but in all that time the technology is still barely able to deal with winter conditions for street going EVs. I am dropping BEV from the list because:

• Phenomenally high cost
• Safety - risk of battery fire particularly with used batteries that could save money
• Excessive weight - wears out a lifted suspension and tyres quicker
• Lack of range for weight of vehicle
• Lack of off road proven components that are both functional and reliable when used off road
• On my own for technical support

 

The list items remaining:

 

3. Rebuild and modify the 4.0L to make it a 4.6L stroker up to 300bhp?

4. Rebuild and modify the 4.0L normally aspirated up to 250bhp?

5. Rebuild and modify the 4.0L forced induction up to 300bhp?

6. Restore the 4.0L with a blue printed rebuild up to 200bhp?

8. Custom hybrid EV conversion on the 4.0L (flywheel motor)

 

 

[stewart]

Just a thought V Why have you not considered the 3.6 Pentastar with the 8 Speed ? We have this set up in Australia in the JL and JT and with the 8 speed are pretty awesome ? Also though stock tune is 285bhp the version fitted in some Doge variants are tuned to 395 bhp? I assume the wrangler is tuned for a better torque curve of raw BHP ? 

As this set up would be a complete package and light weight, Maybe an option? 2012 and prior did have some Cylinder head issue though so avoid that period. As you mention the plastics issue the main one on the Pentastar is the plastic Oil filter / Cooler assembly I replace min with a US manufactured Aluminium one made by Dorman.