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Right Hand Drive UK-spec Turbo 4.0L Overlander

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Right Hand Drive UK-spec Turbo 4.0L Overlander

Old 11-15-2017, 05:57 PM
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Talking Right Hand Drive UK-spec Turbo 4.0L Overlander

Hello folks.

Been on this forum awhile, but this is my first build thread as I wanted to document this build from start to finish. My wife and I are Minnesota born and raised, currently stationed in Germany, and I picked up a project to keep me busy for the next 2-3 years. I found a 1998 Jeep XJ Cherokee in desperate need of love from a gentleman locally, and bought it with the intention of just using it as a winter beater to toss skis on top and head down to the Alps. Well, one thing lead to another, and after finding the inline-6 4.0L had more bottles of stop-leak in the cooling system than coolant, I decided to pull the engine and restore this XJ to roadworthy status...with a turbo... and a slight lift....and tires that can take me to far out places....with bumpers front and rear.....and onboard air.....dual batteries....well you guys own Jeeps - you know how it goes.

Though this is my first turbo build from the ground up, it is not my first turbo project. I was introduced to forced induction during the overhaul of my last project, a '97 F350 Powerstroke which started as a simple fixer-upper and ended up as a fully rebuilt 7.3L, aftermarket turbo, injectors, intercooler from a Superduty, billet trans rebuild and all the necessary supporting mods to pull ~21,650lbs across the US with relative ease. This is what started my love of boost.

My current daily driver is also turbocharged, a 2006 Toyota D-CAT 2.2L diesel station-wagon which gets impressive gas mileage and can still do 200km/h on the Autobahn with not a whole lot of effort. I tow car trailers with this station-wagon, and have no problem filling it with 4 other passengers, snowboards, skis and a week full of gear. I've come to appreciate low-end torque and small turbo/quick spool response from the Powerstroke and Toyota diesels, and it's what I'm looking for in this Jeep 4.0L turbo project.

Add on top of everything it's a Jeep, and therefore has the inability to stay stock, this vehicle will turn into my overlander vehicle to bring me and my wife to the far reaches of exploring the outdoors.

Here's the plan:
  • Phase 1: Rebuild the 4.0L, drive it N/A until Late Spring 2018. Get it dyno'd for a baseline, record baseline MPG as well. Pass German TUV inspection, get my stickers and get it on the road. Address the sagging suspension both front and rear, and replace parts as needed with upgrades towards the goal of overlanding.
  • Phase 2: Turbocharge it starting Late Spring 2018. Finish turbo build, break it in, re-dyno and tune the PCM and use the Jeep for winter 2018/2019 ski season as a daily driver.
  • Phase 3: Continue upgrading suspension and driveline package towards the goal of overlanding on a trip to the Arctic Circle.

Here are the goals (in order of importance to me):
  1. Reliability
    Definition: Reliability to me means starting every time, not leaking anything, not burning anything, and is a vehicle I can hop in and know I can drive 7-8 hours through hills and mountains pulling a trailer with 2 motorcycles on it and not have any engine problems caused by the addition of the turbo.
    Has a 100,000 mile life before needing any major rebuild. Minor parts replacement is ok and understood.
  2. Acceptable gas mileage. Currently, I have an incomplete MPG-baseline for what this XJ is capable of. I literally drove it from the previous owner's parking spot and 1 day later had the engine torn apart in my garage. Being that this is mine (and my wife's) 4th Jeep XJ (we've had a '96, '89, still own a '98 LHD and now this '98 RHD) I know 17-18mpg is not out of the realm of a slightly heavier lifted XJ on the highway, and 13-14mpg when towing a trailer over half the size of the Jeep. When I am finished with Phase 1 rebuilding the 4.0L, I'll be able to drive it long distances on the Autobahn and get a year's worth of fill ups to know my Naturally Aspirated gas mileage averages.
  3. Diesel-like power and response. The stock 4.0L has a fat torque curve with most of it's usable power between 1800 and 4400rpms. This is the target section I want to add to, with a stock redline of whatever it is (5000? 5200?)
  4. Use pump gas both in the US and Europe. No E85 or octane boosters. No meth injection. I'll be bringing this RHD XJ back to the States with me, and I don't mind running 91 octane. But, if for some reason I am detonating on 89-91 at full boost at WOT, I failed in my design or more tuning is needed.
  5. Be capable of excellent road manners in the dry, wet, snow and dirt, handle road curves/switchbacks/mountain passes better than stock (while being lifted slightly), and carry all the gear necessary for a multi-week trail ride and live to tell about it.
  6. Be capable of towing a 3500lb trailer with trailer brakes like it's barely there (focusing on power, gearing, cooling, reliability and overall strength)
  7. Have the ability to submerge or cross water up to the bottoms of the factory doors.

Questions that I have and will continue researching:
  • Well, of course the big question is "which turbo?". I've read literature like Maximum Boost and Turbo: Real World High-Performance Turbocharger Systems so I'm prepared to go through the math to determine flow needs of this 4.0L. I've pencil-sketched the arithmetic a few times to get an idea of turbo sizing for this project, but haven't opened it up yet for others to weigh in on. That will be its own post later.
  • How to reasonably pick a horsepower or boost target, based on the weakest link in the Jeep? Is it the bottom end? Is it the stock fuel system? Is it the stock cooling system? It is the AW4 automatic? Honestly from the get-go I have had 8psi in mind during my turbo math, but more importantly I want to know what the weakest link is when I start spooling boost down low.
  • How to choose supporting parts such as a waste gate, blow off valve, oil pressure lines, exhaust piping size, intake tubing size, intercooling requirements, injector sizing and fueling...ect.
  • PCV and CCV re-design ...this is currently a bag of cats in my head until I get it all figured out. The Jeep 4.0L leaks oil out of the rear main seal, the valve cover, the oil pan, the breather hoses, the timing cover and pretty much every other orifice it can if the PCV and CCV are plugged up and not working properly. A pressurized intake manifold will accelerate this and I'm not opposed to going the extra lengths to design it right.
    I've decided on water-to-air intercooling. But need to figure out my space limitations under the hood.
  • Tuning the PCM... the Mopar/Jeep brain box is retarded compared to today's modern PCM's. I've had our '98 XJ tuned, but that was in the US. Need to figure out who, how and where to get this done in Europe. Internet tunes maybe. Donno yet.

I want to answer a few questions right off the bat to avoid unnecessary forum questions:
  • Why not just stroke the 4.0L to 4.5-4.7 liters with an AMC 258 crank? Done that already. Wife's Jeep has a 4.7L stroker that put down 297lb-ft of torque and 166hp at the rear wheels (35" tires by the way). It gets 14mpg on a good drive, and is stored in Minnesota with my friends & family.
  • Why not just swap in a Chevy 350 or LS-engine? Done that already in other vehicles, multiple times. These vehicles are stored in Minnesota with my friends & family.
  • Why not a 4BT or similar Cummins swap if you like diesel torque so much? The wife said no...and secondly I'm not sure what US state & zipcode I will end up living in after Germany so I don't want to get caught with my pants down having anything but the "original" engine in there.

I will keep updating this picture with each major milestone the Jeep accomplishes.
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Old 11-15-2017, 06:01 PM
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I'm going to save this post for the current build image...updated semi regularly. Hopefully this forum allows for endless future edits, if not, you'll get to see this useless placeholder for years to come.

Attached is the most recent photo/progress made as of 11/15/2017.

Description: Jeep is driving, on it's 2nd oil change by now, and I'm breaking in the new engine.

Attached Thumbnails Right Hand Drive UK-spec Turbo 4.0L Overlander-img_20171008_204637.jpg  
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Old 11-15-2017, 06:09 PM
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Literally day 1 of owning the Jeep. Again, this is a right hand drive UK-spec Cherokee. Black exterior, tan leather interior with wood grain dash.



Below is neat in the way of being different, but more of a pain in the *** now to convert over, are the UK-spec head lights and the headlight angle switch. The idea is to manually aim the head lights for no load on the trailer hitch nor any weight in the cargo area, then when you are heavily loaded down or towing a trailer, you adjust your headlight switch 1, 2 or 3 degrees down so you're not blinding anyone. Over here, Europeans and Brits are very cognizant of their headlight beam pattern. No ******** (so far, at least) with blinding HID bulbs in halogen housings, and everyone seems to be fully aware of the highbeams at night and turning them off as we approach.



As mentioned, this is a RHD Jeep.



This Jeep was retrofitted with a 100 liter LPG (liquefied propane gas) system that was an OBD2 add on/piggy back. In the UK, the gov't was helping citizens with the LPG retrofit and providing rebates on vehicles that had high (bad) emissions and poor gas mileage. The idea was to start the vehicle on normal petrol, get the 4.0L up to operating temp, and then flip the switch to LPG. LPG is/was about half the price of petrol, but you used 1/3rd to 1/2 more LPG than petrol, so it really only paid for itself after many thousands of miles. If you drive a lot, it eventually pays off. There are many gas stations all over Europe and the UK that provide LPG, it's fairly common on major autobahns and highways. I, on the other hand, used the LPG system in this Jeep to drive the price down, because it didn't work, and I didn't care as I have no plans on pumping anything but 89-91 octane petrol with a max of 10% ethanol lol.



So like I said above, this Jeep came to me with a horrible cooling system. The previous owner had filled the radiator with more stop-leak than coolant, and I even found windshield washer fluid in the radiator reservoir bottle! The water pump leaked, and on the highway would spray into the radiator fan, therefore causing "**** to hit the fan" and spread all over the engine bay.







Another leak I found was the heater core.





Upon tearing down the engine, I found literally pounds of dried stop leak in the head, cooling jackets and hoses. The head gasket was so plugged up that very little coolant was getting to the head.








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Old 11-15-2017, 06:15 PM
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So....I packed up the block, head, crank, pistons + rods, intake manifold and other nasty parts and brought everything to the German machine shop.



Block was bored 0.030" over, giving me a cyl bore size of 3.895".









Valves were disassembled from the head, cut and polished. A 4-angle valve job performed.









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Old 11-15-2017, 06:26 PM
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Then began assembly.

The spray paint I chose for the long block surprised me - the can's top suggested the paint color was going to be more flat, kind of like a lighter gun-metal. When it sprayed onto the block, it was more of a bright metal, aluminum, shiny color. Oh well, should be easy to spot leaks!



I weight matched all the piston + rod + ring assemblies to within 1 gram.





Selecting the camshaft absorbed many countless weeks of reading, researching, calculating and watching YouTube videos. In the end Comp Cams won my vote.







New OEM volume oil pump. My last stroker build for my wife's 4.7L straight-6 used a high volume pump, and it required quite a bit of hammering of the oil pan to clear. Even with the additional turbo next year, I'm hoping the OEM pump will suffice. I also swapped oil pan bolts for oil pan studs. Studs FTW.







Head studs FTW, when compared to head bolts. Should do nicely clamping the head down under 8-10psi. I had the block decked 0.5mm (0.0196"), so the piston comes nearly to the zero deck altitude at TDC. This enhances quench. After decking, I re-installed the head dowel studs. The very front head stud that goes into the cooling jacket got thread sealant around it.







See! Royal purple break in oil shows up great on the block's shiny surface.



Stock rockers and push rods, but the valve springs are Mopar Performance springs and keepers to handle the higher lift camshaft. I also shimmed the rocker pedestal to account for the shaved head and decked block height in relation to pushrod length. Also swapped out the factory valve cover bolts for studs, re-tapped the holes and cleaned each one out.











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Old 11-15-2017, 06:29 PM
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As many of you are aware, there is a fine balance between compression ratio, boost, camshaft selection, quench, head selection, fuel requirements, and the end goal of the machine. Countless hours were spent getting this to an acceptable balance between all.

My new build specs:



OEM Jeep Cherokee 4.0 specs:

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Old 11-15-2017, 06:38 PM
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Engine install!



Unfortunately I discovered the crank position sensor (KPS) bolts had a bad burr in the tapped threads of the AW4 bell-housing, so I did what any normal Jeeper would do when stranded in metric-Germany, drill and tap them out larger to metric 8mm!







I got the engine situated sitting on RHD-specific Brown Dog motor mounts, hooked up to the bell-housing and torque converter.




Swapped injectors to the 4-hole design, replacing the O-ring seals.




Also swapped the '98 intake manifold for the horseshoe design 99+ design.
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Old 11-15-2017, 06:50 PM
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Like any normal project, I started installing accessories and discovered I didn't have all my facts straight with this right hand drive nonsense. Turns out the forums are not always helpful, and in fact many things on these RHD XJ's are not interchangeable with LHD normal XJ's. For example, the A/C compressor is RHD specific, and Mopar stopped making it. Therefore, I'm bypassing the A/C for now until that can get resolved. Had to find a shorter belt. The radiator is not interchangeable, and even though it bolts into the core support mounts, the tabs that hold the clutch fan and e-fan shroud are RHD and LHD specific since the RHD has the clutch fan on the other side. That means the LHD radiator that's currently in my rig is not going to work with the RHD clutch fan shroud I'm trying to bolt in...so for now I temporarily mounted it with new bolts and zip-ties. Not ideal, I will return to this. Additionally, the new LHD e-fan I bought now needs to be on the opposite side of the radiator, and does not line up with the radiator slots on the other side. So, I'm not running an e-fan yet. More on that later.





I also take this opportunity to add a much needed transmission cooler, which is currently only installed with the cooler-zip-ties until a permanent solution can be made once I know where all the turbo-piping is going to fit. Also added a trans filter behind the front support brace and completely by-passed the useless radiator trans cooler.







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Old 11-15-2017, 06:59 PM
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Topped off all the fluids, checked all cables, bled the fuel system a couple times, and tried starting it. Fired up on the first try! Unfortunately I realized after I had not tightened the lower radiator hose clamp tight enough and it sprung a leak, but I broke the engine in on water only for the first 20min.

https://photos.app.goo.gl/udQgli811WXf5MUj2

The slow cranking was due to not having the battery installed yet - it was on the garage floor and connected via jumper cables. Excited it fired up!
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Old 11-15-2017, 07:05 PM
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I took note of the mileage at the first start of the engine so I knew what "0 miles" was again on the engine odometer.




I broke the engine in via the typical hydraulic flat-tappet camshaft mentality:
  • Fresh starting oil with high ZDDP content, aka "break in oil"
  • 20-25min of sustained revs above 2000, reving up to 2500 and changing speed between 2000-2500 over the course of those 20min
  • After 20min change engine oil
  • Filled back up with new WIX 1515 filter, new break-in oil change, and will repeat again at 500 miles driven

During the engine break in, the header was getting rosy! I'm not convinced this isn't a problem yet, but so far the Jeep is running quite well.
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Old 11-15-2017, 07:13 PM
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As of today's post, I have about 302 miles on the new engine and have been driving it around Germany and Luxembourg on temporary plates until I pass inspection on base. I've been driving through winding towns, hills, autobahn, and giving it a few 80% throttle blasts here and there up to 4000rpm trying to hit all ranges except for WOT.

I haven't had much time to work on it over the last few weeks as I have been traveling internationally back and forth for work. Unfortunately, I'll be traveling internationally again next week Friday after Thanksgiving as well for 2 weeks, so I don't foresee diving into any Jeep-projects until I return.

Next up *hopefully before I leave for the US*: 4 New tires for winter season, inspection fix-list, battery relocation and rear cargo box build.
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Old 11-16-2017, 03:13 PM
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Originally Posted by Stroked98Xj View Post
Below is neat in the way of being different, but more of a pain in the *** now to convert over, are the UK-spec head lights and the headlight angle switch. The idea is to manually aim the head lights for no load on the trailer hitch nor any weight in the cargo area, then when you are heavily loaded down or towing a trailer, you adjust your headlight switch 1, 2 or 3 degrees down so you're not blinding anyone. Over here, Europeans and Brits are very cognizant of their headlight beam pattern. No ******** (so far, at least) with blinding HID bulbs in halogen housings, and everyone seems to be fully aware of the highbeams at night and turning them off as we approach.


1) I am very, very interested in how those work.
2) Is that a 4 switch bezel I see?
3) Do you have rear fogs? Tell me you have rear fogs...
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Old 11-16-2017, 09:55 PM
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So. Bad. ***.

I love the details in the build. Keep it up!
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Old 11-17-2017, 07:18 AM
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Originally Posted by wizardpc View Post
1) I am very, very interested in how those work.
2) Is that a 4 switch bezel I see?
3) Do you have rear fogs? Tell me you have rear fogs...
  1. I haven't dug into the headlight aiming yet, but the switch on the bezel works. I can hear a relay trigger, then up front I hear an electric motor behind the headlights moving/trying to move. Honestly I don't even need nor want adjustable headlights.
  2. See pictures below. Far right fog light is for the rear fogs.
  3. See pictures below. Both left and right tail housing assemblies have fogs.

Also got new 235/75R15 snow+winter tires today, and failed inspection for stupid things like low washer bottle fluid, disconnected A/C lines for where the compressor should be, and a left drum assembly that does not grab as hard as the right assembly, but it's within spec.

Finally, it failed for an exhaust leak at the muffler, which I knew about and will be getting the entire system replaced from manifold to tip. I already have a new O2 sensor, 2.5" to 3" adapter section, 3" Magnaflow cat, 3" Magnaflow muffler and 3" expansion joint. I found a local German "auspuff" shop (exhaust shop) with a mandrel bender to build a 2.5" downpipe until right in front of the trans pan, then insert the 2.5" to 3" adapter section up to 3" pipe to go over the crossmember, flow into the cat, then muffler, then out to the bumper's tip. I wanted the ability to add the turbo next year without having to re-do the entire exhaust system again. I know 3" is overkill for the N/A 4.0L, but it's the exact same diameter as the turbo downpipe.









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Old 11-17-2017, 10:14 AM
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Thank you that's very helpful.

It never occurred to me that the rear fogs were red!


BTW, when you come back to the states, you're going to want to bring that 4 switch bezel and the tail lights with you.

Last edited by wizardpc; 11-17-2017 at 10:28 AM.
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