Home How-to Articles Moses Ludel’s 4WD Mechanix Magazine – Jeep XJ & MJ Engine Upgrades and Swaps

Moses Ludel’s 4WD Mechanix Magazine – Jeep XJ & MJ Engine Upgrades and Swaps

by Moses Ludel
Q&A for Jeep XJ Cherokee and MJ Comanche: Engine Upgrades & Swaps

     Enjoy the many detailed, traditional ‘Q&A’ exchanges in these article columns…’Q & A’ has now moved to open, interactive forum discussions. Visit the forums, you’ll want to join—for free!

     Have technical questions about your Jeep 4×4,  popular 4WD truck, SUV, ATV, UTV or dirt motorcycle—or welding and metal fabrication? The 4WD Mechanix Magazine ‘Tech and Travel’ Forums now feature enthusiastic discussions and input from members and our staff—including comments from Moses Ludel

     For an HD video playlist, featuring the latest Q&A vlogs with Moses Ludel, click here for the “4WD Vlog and ‘Live Tech’ Q&A Channel”.

Want to discuss your technical and outdoor interests with like-minded enthusiasts? Check out the 4WD Mechanix ‘Tech and Travel’ Forums!  Click here for a guest visit to the forums! 

Griffin prototype advanced cooling for XJ Cherokee

From: Aaron McDonald [mailto:aaron@aaronmcdonald.com.au]
Sent: Saturday, September 29, 2012 3:49 AM
4WD Mechanix Magazine
Subject: Griffen radiator for XJ Cherokee

Hi, I just watched your video on the new radiator install on the Cherokee XJ. Can you tell me where I can get one of these from as I can’t seem to find anywhere online.

Thanks and regards,


Hi, Aaron…The radiator I installed is a prototype for a new design offered by Griffin.  I have heartily encouraged production of this unit, it’s a great fit and success story for cooling.  Every word shared in the videos is accurate and further reinforced by my evaluation and testing over a long, hot summer at northern Nevada. 

Testing now includes A/C running continuously with ambient temps above 100-degrees F, high desert country trail running, stop-and-go traffic at Reno and heat cycling from startup to squelching heat soaks after shutdown before restarts.  Restart after brief (2 minutes or so) fan run-on is at 185-degrees F every time—as noted in the videos.

The favorite temperature of this cooling system is at thermostat setting, with a peak rise of five degrees F under the most strenuous tests.  The twin Spal fans are very impressive, bringing temp down to thermostat set point immediately, regardless of driving conditions!  These fans, set to run after engine shutoff, will bring the radiator temperature to 185-degrees F in just over two minutes, even when ambient temperature is 105-degrees F, and the vehicle is parked in the sun. 

Beyond the advanced engineering of the radiator unit, Griffin has creatively mated the Spal twin electric fan and shroud system.  Ancillary benefits include a bump in fuel efficiency and noticeably more engine power.  Griffin has built a state-of-the-art, proprietary radiator and fan system here. 

I will contact Griffin Radiator this week and see where the production/marketing stands with this XJ Cherokee radiator and fan system.  Expect an update, Aaron!


Moses Ludel

Tony Hewes and his 4.6L stroker Jeep inline six at Hewes Performance Machine, Reno, Nevada

Middle East Cherokee 4.0L Ready for V-8 Swap or Stroker Build-up!

From: Ibrahim, Saudi Arabia Cherokee owner
Sent: Saturday, July 14, 2012 3:00 AM
   4WD Mechanix Magazine
Subject: For 2000 Jeep Chroki Saudi

Hello, my name is Ibrahim from Saudi Arabia

I have a [Chroki] Sport model 2000 Gulf. Searched a lot and tired search. We do not have [Cherokee] experts in Saudi Arabia. I am a fan of speed and high performance. One person said to me that the engine should be replaced with LS1 V-8 to enjoy high-performance.

First, to avoid cost, can you equip [Chroki] engine 6 cylinder stroker with a computer to re-programming, and how much it cost? Is there a difference high-performance, and how much HP will I get it?

Second, you could add a turbo engine [Cruki] without any additions?


Third, you can install the engine Ford Mustang [Cruki]? Where you think that the cost will be less.

I apologize if my style is not good writing, I do not speak enough English.

thank you

Hello, Ibrahim, pleased to receive your questions…You are asking about the Cherokee 4.0L inline six-cylinder engine and stroker rebuild.  I believe this is the best and simplest way to gain performance from an XJ Cherokee Jeep.  At the magazine website, you will find a series of HD videos, including an interview with Tony Hewes at Hewes Performance Machine, Reno, Nevada, USA.  Tony builds the 4.6L Jeep stroker six-cylinder engine.  I agree with his methods and choice of parts.

Here are links to the HD videos at the magazine site.  On the sub-pages to this link, you will find six additional videos plus more videos on tuning the 4.6L six:


This should help clarify the 4.6L stroker inline six build for the Cherokee engine.  Although supercharging is available for the 4.0L engine, the stroker crankshaft provides dramatic gains—with or without supercharging…

Glad to share, Ibrahim.


Shannon Campbell's Ultra4 uses LS V-8 power, as do many racers. Note the cooling system required for desert use!


From: Ibrahim at Saudi Arabia

Sent: Saturday, July 14, 2012 11:36 PM
To: 4WD Mechanix Magazine
Subject: RE: For 2000 Jeep Chroki Saudi

Hello Moses,

Thank you for your response to the topic. Yes I mean 4.0L engine.
 The modified engine results will be strong or replace it with another engine? Often we have been installing V-8 LS1 engine or turbo 2Ji. What do you think Mustang engine for installation in [Cruki]? For a system re-programming the computer one person advised me to install the EMS computer will get better results if inserted at the left engine case. What would you recommend?


Ibrahim, the stroker 4.6L Jeep inline six will produce 230-300 horsepower, depending upon the compression ratio, camshaft choice and other modifications. If you want maximum dependability, the 230-250 horsepower build (Tony Hewes’ versions) make the best sense.

I do like the Chevrolet LS1 and also the Mustang 5.0L and 4.6L V-8s. These are options but require adapters, fabrication work and a suitable transmission. There is much construction work involved, and you either need a well-equipped shop or a budget to sublet this work to a suitable shop.

The Mustang 302 (5.0L) HO pushrod V-8 is a proven, reliable design. There are adapters and transmission alternatives for this swap or the G.M. LS1 V-8. (Visit www.advanceadapters.com, an advertiser at the magazine.)

You could expect 240-300 horsepower from a stock or lightly modified 302 Ford H.O./MPI V-8, depending upon compression ratio and camshaft, valvetrain and other modifications. The LS1 offers more horsepower in stock form…There would be a custom cooling system required, and you live at Saudi Arabia, so engine cooling is an issue.

Given the amount of work involved, the 250-300 horsepower from a 4.6L inline six Jeep stroker engine would be the easiest and least involved way to achieve your goals for the Cherokee.

You can have a stroker Jeep six motor built at Saudi Arabia by a qualified automotive machine shop. U.S. cost ranges from $3000-$5000 for a thorough rebuild and the necessary modifications. A shop can review my magazine articles and HD video series for ideas on how to build the engine.

The cooling system and fuel injectors do need attention. The PCM (original Cherokee computer) will work with the stroker six build-up. Many change the fuel injectors to 302 Ford V-8 type at 24 lb. rating. I am researching a specific part number that achieves the desired results.

There are replacement injectors and other information available at the HESCO website: http://www.hesco.us/shop.asp?action=cat&catID=7550. Visit the HESCO Jeep website and see the additional information on the stroker 4.5L to 4.7L inline sixes. HESCO also offers its own aluminum cylinder head for those who want maximum performance. They sell the many parts used in the stroker six build. HESCO also has dynamometer results for various stroker engine builds.

Hewes Performance Machine at Reno, Nevada can build a complete stroker 4.6L like you find at my magazine. You can reach Tony Hewes by Email or phone. My magazine articles include the Hewes Performance Email address and phone number.

This should help clarify the cost of building a stroker six. Also see my latest tech coverage of the Griffin Radiator for the Cherokee. That radiator would work well with a stroker six. This new design Griffin Radiator will be available soon.


Moses Airing XJ Cherokee Cooling Issues

style=”margin: 0in 0in 0pt; mso-outline-level: 1;”>Note: I shared comments with my friend Jim, an XJ Cherokee owner and former aircraft engineer. The following E-mail exchange ensued. I will continue to address cooling system issues on the 4.0L and other Jeep engines…

Moses: Jim, I had a burst of inspiration today while wheelin’ with a group out of Gardnerville, shooting some graphics for the June issue. The XJ engine, despite the mild April temperature and use of lower range gearing, hovered around 210-degrees F on the temp gauge. I began connecting what the terrain demanded with the engine temp…the automatic transmission [AW-4] is clearly involved. I’m now curious whether owners with manual transmissions have this temperature sensitivity issue. Regardless, the XJ is a fine candidate for a transmission cooler! A synthetic ATF, if specified for use in this unit, would not be a bad idea, either. 100% synthetic ATF can drop trans temp as much as 50-degrees F…

Jim: I have been using 100% synthetic ATF in the AW-4 since day one. I’m a believer. I use the Amsoil Universal ATF but there are others out there, including a Mobil 1 version. I think they really do help. They do run cooler—they lubricate better so things don’t get as hot and they have a higher heat transfer rate than standard ATF, so they give up more heat when they go through the radiator and transmission cooler. If things do heat up a bit, they can run a lot hotter than standard ATF without breaking down…That’s three good reasons to run synthetic ATF. I’m curious about the cooler—my XJ came standard with an auxiliary cooler sitting right in front of the radiator and clearly visible behind the grille. You don’t have one? Must be part of the tow package.

Moses: My XJ does not have the cooler. However, I’ve worked with automatic transmissions and coolers since 1969. In my view, a cooler in front of the radiator is a liability. I always mount the cooler behind the radiator. Although the air passing through it is hotter (preheated from the radiator, essentially), this is still better than mounting the cooler (which is much hotter than the radiator coolant) in front of the radiator. In front, the hot air heats a section of the radiator core. On an XJ, that’s a liability…Just running auxiliary lights in front of the grille was enough to overheat the engine in the summer! Imagine blocking the core with a “heat cell” like a transmission cooler. Bad enough the air conditioning condenser is out there…So, what I will do is mount an auxiliary (cooler fin-to-air) cooler behind the radiator, definitely in the air stream, not necessarily in the fan flow stream unless I can find a low pressure zone that is not flowing hot air from the radiator core. The aim is to keep heat-saturated air from the radiator core from passing over the transmission cooler. The downside to this approach is that the trans cooler’s air supply is likely more static and reliant on ambient air or road speed air/draft for cooling…On that note, I might build an air draft fin to create a low pressure zone behind the auxiliary cooler to draw air over the cooler—this would at least work with the vehicle in motion…

Jim: Several cooling system upgrades have helped my XJ. These have included an improved flow thermostat housing and a water pump with improved impeller design. If you want to go that far, there are aftermarket radiator options as well.

Moses: I’ll do a comprehensive test before sharing information in the form of magazine articles. These ideas all make sense. The best approach is to systematically make individual changes and measure the gains, if any, from each…Thanks, Jim.

Diesel Discussion Continues!

Considering your comments on a diesel swap of the VM 2.8L (J8 engine) into the XJ Cherokee, I think this would be a brilliant idea! I have considered this swap for a while now. A Mopar diesel engine is a more attractive idea than finding another random diesel. If you end up doing this, would you provide general cost break-downs and the suppliers you use?

Matt G.

Matt, thanks for the supportive reply! I’ve toyed with this idea since the Liberty began offering the 2.8L CRD option. At Moab, after a closer look at the J8 package, the concept gelled. I spoke with some Mopar colleagues about the prospect. As the result of some research, interesting facts have surfaced. 

Mopar Underground staff has played with Liberty engine swaps, and apparently, the computer (PCM) has a key code that interfaces with the ignition switch. This safety/security approach means that the ignition switch must be an integral part of the swap. Based upon the Underground’s resources, they use a donor Liberty model and swap out the engine/transmission plus the entire Liberty steering column. It’s possible that the J8 does not have this level of sophisticated PCM security. Imagine the consequences if a military J8 operator were to misplace the keys to the vehicle! Given that proviso, I would be game for the swap if enough readers like the diesel concept and if the projected costs are practical. I would swap the engine-transmission unit and mate it to the XJ’s existing NP231 or a J8 transfer case, or possibly an Atlas II from Advance Adapters. I would do the swap with all electronics and wiring included.

If the prospect has a following, my aim would be to encourage Mopar to offer a “package” of assembly line pieces that make up the swap. It would be necessary to make the complete J8 powertrain available through Mopar, as consumers would find it impossible to buy a surplus Egyptian military vehicle. All of this requires a commitment from Mopar.

One thing is clear, Matt. 30 mpg on the highway and peak engine torque of 295 lb-ft at 2000 rpm for backcountry crawling are the performance gains we should all want at this point. Fuel costs won’t get any cheaper, especially with oil spilling into the Gulf of Mexico and fostering an ecological nightmare for Gulf States residents. A high-tech, EFI/CRD 2.8L four might be just what modern ‘wheelers need!

To whet appetites, here’s a rundown on the VM 2.8L engine performance (data courtesy of a Wiki entry on the J8 subject):

J8 Engine and Transmission…

The engine for the MILSPEC J8 is manufactured by VM Motori S.p.A. based in Cento, Italy:

Engine code: R 428 DOHC “Panther”

Displacement: 2.8L (2766 cc).

This engine has four valves-per-cylinder and common-rail direct fuel injection technology. It is essentially an R 425 DOHC 2.5 L (2499 cc) enlarged to 2.8L.

Max Power: 118 kW (158hp) @ 3800 rpm

Max Torque: 400 Nm (295 lb-ft) @ 2000 rpm

The Transmission is a Chrysler 545RFE five-speed, electronically controlled automatic linked to a Command Trac 4WD system with 2.72:1 low range.

This 545RFE is in turn based off the 45RFE 4-speed transmission with the addition of a 5th forward gear.

 Standard Ratios are:

 1st 3.00:1

2nd 1.67:1

2nd Prime 1.50:1

3rd 1.00:1

4th 0.75:1

5th 0.67:1

Reverse 3.00:1

Worth noting, AEV has an in-place 2.8L CRD conversion that suggests some cost obstacles. For more information on AEV’s approaches, there are comments at the AEV site:


and http://www.aev-conversions.com/news/?p=172

If this swap and a J8 type vehicle are as costly as AEV indicates, we’ll be back to the drawing board for XJ Cherokee owners. Unless readers can benefit from a practical, affordable way to defeat high fuel costs, using a contemporary, hi-tech, clean tailpipe diesel, I have no designs on installing a J8 powertrain in the magazine’s test-bed XJ. At 4WD Mechanix Magazine, it’s about technology that meets readers’ needs and budgets.

I’m open to readers’ thoughts on engine alternatives, with these caveats: a clean tailpipe, improved performance and an affordable approach.

I’ve peeked at the Cummins offerings, as I’m thrilled with our ‘05 5.9L Ram six-cylinder engine! In four-cylinder industrial versions, however, the Cummins is too heavy and shows unimpressive output. Any experience with an Isuzu or Mercedes medium duty truck design?

Cost must be reasonable and amortize quickly as fuel savings. The swap must be affordable for an XJ/TJ or JK owner, with substantial performance and mileage gains.

I would do the entire swap in a step-by, instructional format. This includes mount fabrication (engineering, welding and fitment), detailing all modifications (cooling, electronics, exhaust solutions, transmission, driveline, wiring, etc.); the sources for swap pieces, costs as you suggest and, ultimately, some bona fide, “real world” testing of the package before others commit.

Thanks for your interest in the magazine and its projects, Matt. We’ll stay in contact and weigh other readers’ responses and ideas. I’m more than ready for clean tailpipe diesel power in the XJ Cherokee—or any other Jeep model!

Two Jeep Cherokees Need Exhaust Upgrades

I saw your article on the exhaust upgrade you did on a ‘99 Jeep Cherokee. I would like to do the same modification on my 2000 Jeep Cherokee. Is this possible?—Jennifer 

I talked to a Borla specialist. Their kit was not tested on the ’98-’99 XJs. I will definitely go with the ‘00-‘01 kit. Your article will be helpful if I run into minor misalignments. Thanks for your advice.—Vago

Note: Jennifer and Vago refer to my XJ Cherokee exhaust system article in OFF-ROAD Magazine. When routing the tailpipe between the frame and right rear spring, be aware that our XJ chassis has a 6-inch lift kit installed! Stock spring arch may not provide enough clearance here…Changing a 4.0L Wrangler, Grand Cherokee or XJ Cherokee exhaust manifold is a major task. In the article, I show how to save time swapping manifolds. Even so, this is a complex job that requires the right tools, time enough to get the job done right plus cutting-welding equipment for the hanger changes…

Borla exhaust system for the XJ Cherokee

For the magazine project, I used the 1997 Borla XJ kit for our 1999 XJ Cherokee chassis. At the time, Borla only offered Jeep XJ systems to fit through 1997, essentially kits still supplied to Mopar Performance. The Borla header is identical for TJ and late XJ applications, including the ’99 model. Borla’s ’97 XJ package includes the Borla header, header-to-cat pipe, a performance muffler and a new tailpipe plus high-quality clamps. For peak performance, I added the Random Technology catalytic converter. This package turned out to be a good approach. Only four modifications were needed to fit the system to this 6” lifted ’99 XJ chassis: 1) a modification to the head pipe-and-cat support bracket that fits at the transmission mount, 2) careful routing of the tailpipe with a drop bracket to relocate the attachment point for the axle position tailpipe hanger, 3) making an offset bracket to position the tailpipe away from the fuel tank at the tank position hanger,  and 4) careful routing of oxygen sensor wires and wires from the crankshaft-flywheel position sensor. (Keep wires and plastic convolution shield routed away from the header heat!) As for gains from this installation, Borla’s superior quality pieces replace the crack-prone factory header and a stock head pipe that is highly restrictive. Dyne-tested, Borla’s scavenging gains are legend. For quality and fit, Borla is tops. If the stock exhaust manifold has a crack, the Borla system is a very wise replacement.  In terms of installation difficulty, a header swap is complex—just like replacing a stock manifold. Be aware that a major tune-up—including new plugs, cap, rotor, air filter and plug cables—accompanied this exhaust system installation. With the exhaust system upgrade and tune-up, mileage jumped 2.8 mpg on the highway at cruise! (Mileage gains tend to vary; realistically, though, the engine now breathes freely and accelerates much better than prior to this work.) Before investing this kind of effort, you might try a major tune-up first, and see how much of the 2.8 mpg gain is achievable with just tuning. As I emphasized in the OFF-ROAD Magazine article, periodically tuning the engine and installing a clean air filter will improve fuel efficiency and performance…For those interested, I do tune with genuine Mopar filters and ignition components… 

You may also like