Engine Swap: GM Gen IV L92 Makes Big Power

12. The transmission used in this swap is the GM 6L80 six-speed automatic. This transmission is best used with a Gen IV reluctor engine controlled by an E38 computer. The 6L80 electronic transmission control module must be pulled from the tranny and delivered to the tuner to be reprogrammed for the vehicle swap.

13. The tail of the 4WD 6L80 has the same bolt pattern as the very common 4L80 transmission, so mating up a transfer case means you have several options. In this case, John chose to go with a 3.0:1 Atlas transfer case, which bolted right up.

14. Here’s a snail’s eye view the bottom of the drivetrain. The L92 comes with a deep aluminum pan with rear sump. Behind that you can see the aluminum transmission bellhousing and the deep fluid pan for the auto. Crocker used a set of factory transmission hard lines that fit under the tranny and engine perfectly. Where the lines emerged under the radiator, the crew cut the lines and then spliced to soft lines routed to the cooler in the radiator assembly.

15. When it came time to hook up the transmission shifter, Crocker installed one taken from a 2011 Chevy Malibu. It can shift normally to Park, Reverse, and Drive. But, it can also go into manual mode allowing the driver to tap shift up and down through the gears with a button on the side of the shifter knob. Very slick!

16. Auto Meter gauges were skillfully adapted into the dash of the Jeep and were wired and plumbed to the engine to provide vehicle vital signs.

17. Add a big motor and you’ll need to consider how much strength you have in the rest of the drivetrain. In this case, John opted to upgrade the rear axle to a Currie-built Dana 60.

He originally had 4.10 gearing but swapped down to 3.73 gearing. While the lower gearing (higher numerically) may seem like a great fit with the 33-inch tires John is running, a motor with this much horsepower and torque on a light vehicle is much better behaved with the 3.73 gears.

18. With the swap complete, this rig scoots with about 450 hp (with the retune). It has the smooth power of a modern engine and a six-speed tranny with tap shifting at the owner’s finger tips.

18. With the swap complete, this rig scoots with about 450 hp (with the retune). It has the smooth power of a modern engine and a six-speed tranny with tap shifting at the owner’s finger tips.