[XCRN]

I am in the process of building a new drivetrain for my LS swapped TJ Wrangler, and since starting from scratch I want to see what I can do to make it more fuel efficient, primarily to extend the range more than save money. Obviously a V8 brick can only go so far but I have what I believe to be realistic goals.

Now I am wanting to build a new powertrain, one that has a bit more power but can be more efficient. I have an aluminum 6.2 L92 VVT engine as a base with a 6L80 from an 07 Escalade. Given the nearly 6000lb luxory brick this motor came from can get 13/20mpg, I am sure my 3200lb brick could get better. Ideally I would like to reach or exceed low to mid 20s highway and 16 or above city. Obviously anything over would be better.

As a baseline, when this was a stock 4.0 and 5-speed no doors no top it got I think around 11-12mpg mixed city/country typically from what I recall but I have had it has high as 18-19 on the highway with doors and soft top. I remeber having to drop it down a gear multiple times and give it 100% throttle just to maintain highway speed on windy days.

With a cammed 5.3 LS from a 2000 Silverado with a Holley Terminator X using the Jeep 5-speed no doors or top I get a pretty consistent 13-14 mixed city/country. Since finishing the build I never really got solid highway data, it still struggles but not nearly as bad and I can stay in 5th the whole time with plenty of passing power. So it managed to get better slightly with 100 extra hp and an engine management meant for race cars.

So now my question with rebuilding this new 6.2 from scratch, what are some things I can use to make this engine more effiecient? Is there camshafts that would be better for fuel economy or is a factory cam the best? I have also considered the idea of destroking with a 4.8 crank, but not sure if that would make any worthwhile gains. I plan on using a factory E38 PCM, and because I will be going to some very remote areas with limited fuel options so I need to
safely be able to run 87 octane so a stupid high compression ratio is not ideal.

Right now I have a 6L80 6-speed auto that I could rebuild, is there anything I can do during the rebuild to help increase efficiency? Could I do more with a 4L60? would like to stick with a manual, but no way the stock NV3550 will handle the power without worry.

My primary concern is extending range, which making the engine more fuel effiecent will be a big part of this. Anyways I hope to hear from this knowledgeable community on reaching or exceeding my goals.