The Titan engine is bigger and heavier than an LS. I say this bc of the small size of the 1st gen Xterras. LSs are very compact and light. They weigh about the same as a VQ40 from the 2nd gen Xterra.
The problem with the 6.6 Duramax and the Cummins 6BT is that they are really heavy and big externally. To put it this way, the 4BT is basically a 6BT (think Dodge Cummins) with 2 less cylinders. The 4BT weighs like 750lbs so you can imagine how heavy a 6BT is. The 6.6 Duramax is like 900lbs. Cummins 6BT is like 1100lbs.
The GM 2.8 Duramax is of course an option if you either have a bunch of money or are lucky enough to find one in a salvage yard.
Cummins also has a 2.8 4 cylnder crate motor but I think they are $20-$25k.
In my opinion a VQ40 or LS would be the best choices.
Well some of that I'd have to politely disagree with as weight class being what a concern over. Sure the weight is there, NOT discounting the obvious but you're also missing several other factors. Power and Tq are going to increase as well not to mention power to rate ratios. The Titan motor lends itself to similarities in wiring and technology and it practically bolts in. On top of that if you HAD TO, you could still get a Nissan tech at a dealership to work on it. Possibilities of having to do that if your doing the swap is rare in this case id say but still. The advantage the LS would seem to give is that the randomness of parts are fluently strewn upon ANY autoparts store.. I'm pretty sure thats due to 30 Million recalls, Luck is preparation meets opportunity
I think you would have to not so much do a lot to a 4bt but I think from what I've seen, the 6bt would be more than adequate. GVWR on a 1st gen Xterra vs a Dodge 2500/3500 Single or even dual axle i dont think the vehicle would have a problem dragging the Xterra around being 2300-3500lbs less of a vehicle. Case in point - 6bta Loaded 2nd Gen Xterra::
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And just for good measure, 4BTa loaded Mazda Miata::
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Lil Miata doesnt seem to be struggling with a 745lb engine swapped from its measly and anemic 1.6/1.8L
I will agree finding the Duramax would be a snow balls chance in hell find, it was the idea, and then again there are always crate motors assuming this isn't all based upon what can I find and finance from a junkyard ONLY thought process and Project. To me as a Gear Head and with all do respect, the LS swap just seems like going back to an old Girlfriend over and over because yes its drama, yes its old, yes its PITA, but despite all the anguish its all familiar and mostly tolerable.
Although I dont distrust what the Cummins 2.8L R is capable of, but so far I am impressed. But cost factors are centered around $8000 not $20-25k. Essentially providing everything you need to start your engine with the exception of a battery, cooling package, and of course, diesel fuel! The kit (PN 5467046) also includes:
- Complete front-end accessory drive (Alternator, Power Steering Pump, Fan Hub, Serpentine Belt)
- Cam-Driven Vacuum Pump
- Remote Fuel Filter/Water Separator
- Remote Oil Filter
- Mass Airflow Sensor and Housing
- Engine Wiring Harness and Engine Control Module
- Starter
- Flywheel
- Universal Vehicle Wiring Harness
- Throttle Pedal
- J1939 CAN Dash Display
- Owner’s Manual
- Installation Guide
- Cummins Quick Serve Online Access
- Emissions Testing Information
https://cumminsengines.com/repower.aspx $8999
I sit corrected... But if I become a dealer, I'll give anyone a discount at $14,999.. >

lol JK
Either way, Plans are a 4BTa is scheduled for my main overland rig, and although the 13' Xterra has just over 70k on the clock. Trust in Nissan's and my skills should allow me just enough time to secure a 6BTa and all that will be needed to do a swap of my own. I have specific plans and needs in mind. For that I need what I need and Cummins fits that build parameter bill.