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Swapping a Cummins in a TJ Wrangler

A Great Crate Diesel

Fred WilliamsPhotographer, Writer

Never before have so many folks been interested in an engine swap we’ve done. The new Cummins R2.8 turbodiesel is what many have been asking for, and there is a very good possibility this is the engine you will want in your next little off-road project.

To start, this is not the 4BT that so many have heard about. The 3.9L 4BT is tough as an anvil but also big and very heavy. The R2.8 is a smaller, more modern, and much lighter-weight 2.8L engine that’s perfect for stuffing in a small Jeep Wrangler—and that’s just what we did.

The electronically controlled common rail 2.8L is based on an engine family used overseas in everything from small Chinese pickups to large Brazilian Ford trucks, and with 267 lb-ft of torque and 160 hp it is just what the doctor ordered to replace our tired 2.5L four-cylinder gas engine in our 1997 TJ we call Tube Sock. This new diesel has more torque than the tried-and-true 4.0L Jeep straight-six as well but is comparable in weight to the I6. However, the mileage of the Cummins should be about 30 percent better than the gas engines and deliver similar power and torque at a lower rpm, all great attributes in a four-wheeling engine.

As of this writing, Cummins has not released prices or sales structure (where to buy), but we would guess the R2.8 package will retail between $8,000 and $10,000 and will be sold through the current Cummins dealers. The biggest unknown currently is the California Air Resource Board, which is reviewing the Cummins application for an Executive Order (EO) number designating what year vehicles the engine can be used in for a legal emissions-compliant swap. Last fall, Cummins demonstrated a 25 percent reduction in CO2 emissions and lower hydrocarbon emissions too in the R2.8 as compared to the 4.0L. Cummins wants to offer the R2.8 as a 50-state-legal crate engine, even if it means only in certain older vehicles. We will have an update soon if and when CARB makes a decision.