Morning, folks!

Hoping to get some input from everyone regarding some swap options I'm faced with. I'm in the midst of planning my gearing swap and installing an Ox Locker up front and Limited Slip in the back. Next step will be a power adder in the form of a swap. These are the options I'm debating right now:

V8 Swap (2 Options)

- Chevy V8 (5.7 or 5.3) with 4L60/65E
- AMC 360 with AW4

Either option here gives me the most power with potentially better fuel efficiency if I go with a newer 5.3 swap. This is also a costlier swap, and going with a Chevy V8 leaves me with a 4LXXE variant, of which I'm concerned given in stock form they don't seem to last behind increased power from their native engines. The AMC 360 gives me the benefit of retaining my AW4 (get the flexplate match balanced), but I'm not sure how it'll fit compared to the Chevy V8. I'd also have to make my own motor mounts and headers.

Stroker Build (2 Options)

- 4.7L High Compression Stroker
- 4.6L Low Compression Stroker with Side Mount Supercharger

Obviously the benefit of the stroker lies foremost in its simplicity: old engine out, new engine in. No custom mounts or exhaust routing. Going the boosted tech side mount route also gives me more power on demand as needed, not all the time. Cost plays a factor moreso in the boosted application. A con of both is that premium fuel will be a must, which isn't a big deal breaker.

OM617 Diesel Swap

The ultimate bug out choice. This is also the most complicated and expensive option. Factory output of the 5 cylinder oil burner isn't adequate, but a good turbo swap with a 7.5mm IP and intercooler gives you solid output. All mechanical to boot. Lot of guys getting mid-20 mileage in these swaps. Engine mounts are readily available, as are AW4 adapters and serpentine conversion kits and...and...and... $$$$. Biggest hurdle is oil pan: it's a front sump aluminum pan that interferes with the steering. Modding a pan takes TIG welding, which I can't do. The IP upgrade is $1000+. This swap would get pricey.


So there it is. I'm split hard between all options with a minor lean towards the stroker build. Let me know your thoughts!

 

My vote is stroker motor set up to run unleaded regular.

Reasons for my vote are simplicity, ease of installation, ease of maintenance and ease of supply.

Diesel conversions have always been intriguing.
​​​​​​They serve a purpose and make sense for a lot of reasons.

If the primary reason is fuel mileage then in that case they are false economy. A 1.5 - 2 inch lifted XJ with skid plates and 30-9.50-15 AT tires can be modded to crack 24+ mpg at 60mph for around 1k. Call it 600+/- if you install the parts your self.

 

There won't be much difference at all in fuel milage between a 4.7 stroker or a Chevy V8. A diesel swap will get you better milage but the only diesel I would use is a 4bt Cummins.

 

Yup, Cummins is king. The bad news is it weighs a little over 200 pounds more than a 4.0 and makes 20 less horsepower unless it's modded. They do make more torque though. Parts are more readily available than the Mercedes diesel too.

If a diesel swap is about fuel economy to save money somebody is going going to post you'll never save back the cost of the conversion. They'd be correct on that and at the same time they'll never save back the cost of the lockers and lift kit they bought either.

If a diesel swap is about increasing single tank un refueled range, that's no different in principle than any other mod that owners do to an XJ to make it how they want it.

 

You can get an extra 50-60 HP and 100 ft lb of torque out of a 4BT for free by adjusting the injection pump.

 

One plus for the Chevy V8 is that they are designed to run at low rpm for milage purposes. I have a 4L60E and it has been problem free. But it has been upgraded and most importantly has synthetic oil in it. That is one of the ways to make any auto tranny last much longer. If it does get hot, it does not have the burned oil symptoms of paraffin based oil. It also has a 30% overdrive for that extra milage out of the 5.3