Planning & Plotting a YJ Wrangler Repower: So Many Options, Only One Engine

Picking a Powerplant for This Plucky Puppy-Dog YJ

Christian HazelPhotographer, Writer

Every now and then a vehicle transcends the boundary between simple transportation device and valued family member. That’s what happened with my 1989 Wrangler, Project Why-J. I originally bought it back in September 2008 for a paltry $500. The clutch master cylinder needed to be bled and refilled, and it needed a battery; otherwise I put the little Jeep into daily service. As the technical editor of Jp magazine at the time, I covered a series of mild modifications ranging from upgrading the factory axles with 30-spline alloy axleshaft, Eaton E-Lockers, and 4.88s, to a 2 1/2-inch Rubicon Express suspension, upgrading the NP231 to 3/4-ton specs with internals from JB Conversions (, and swapping in an AX15 transmission with the help of an Advance Adapters kit ( There were obviously more stories I did with this Jeep over the ensuing 11 years I’ve owned it, so search for “Project Why-J” for more stuff like the GenRight rollcage (, Bestop interior (, and much more.

But throughout all the modifications one thing has remained more or less constant: the factory 2.5L TBI engine. With about 250,000 miles the engine is by now really, really tired and has begun suffering from hard-start and stalling issues. I could rebuild it and go through the various injection components, but I think it’s time for a repower. The AX15 transmission will be great for anything from an LS swap to a Cummins R2.8 repower to … oh, I don’t know. I’ve come to enjoy the limited power output of the 2.5L. It has forced me to slow down and smell the roses. Heck, this Jeep doesn’t even have power steering. I don’t need 1,000 hp, so I’ve got my engine swaption choices narrowed down to three: either a Cummins R2.8 crate engine, a TDI turbodiesel out of a wrecked VW, or the old 3.9L all-aluminum Range Rover V-8 that came out of Tech Editor Verne Simons’ Derange Rover UA2018 project build. Otherwise the Jeep will only require a few minor refreshers, which you can read about in the captions.

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