[chillsworld]

Originally Posted by aardvarcus

I am doing something similar, as I needed a good fuel economy vehicle to get to work and back, but I wanted more capable machine both on-road and off-road. I started with a Chevy 1991Regular Cab K2500LD 5.7L V8 that I already had that always got 10-12 MPG, and was able to get it up to 18 MPG average. That involved (in order of magnitude) a transmission swap (auto->manual), driving style, tire swap, air dam, fluid changes, etcetera. I eventually realized I would be better off starting with something that fit my needs better, so I got a 2005 Toyota Tacoma Access Cab 2.7L 5-Speed 4x4. Right out of the gate I instantly got 26+ MPG. The Tacoma is no slouch in the off-road world either.

From 10mpg to 18mpg... NICE! For me though, I don't have the money or skills to swap in a manual tranny. I'm sure if I did a manual and 4wd instead of AWD tcase, I would see upwards of a 30% increase in FE while in RWD. Oh if only I had my own shop and a big bank account! A taco, that was quite the upgrade for you!!

I am not trying to dissuade you from “running what you brung” as that is always a good idea, just make sure you are going to be happy with the finished result before you put lots of time and effort into it. I have been there done that and it’s not fun. Also don’t discount the capabilities of your stock vehicle, get some decent recovery gear and a buddy and go see what your vehicle can do before you spend a bunch of money and time improving its off-road abilities. If you don’t already, look on expeditionportal, plenty of people on there doing incredible things with almost stock vehicles. Too many sites telling you to never even leave the pavement unless you are locked, lifted, 37s, and one tons.

Unfortunately, a car payment isn't a financial reality right now... And finding a 4wd ranger, taco, frontier, etc in a cash and carry price has proved beyond difficult for me (I've been looking!). I know all too well, that I won't be happy with the end result when compared to what I could have. But the end result will be better than what I currently have. And I'm not really trying to improve my performance off the pavement, I'm trying to improve FE that will survive off the pavement. I have recovery straps, axe, shovel, come along, couple wooden blocks for leverage, etc. I know the limitations of my truck pretty well.

I have spent many an hour reading and drooling over at expeditionportal... My dream is to live out of unimog or similar vehicle

I have had many of the same ideas you have had with regards to underbody armor, but the trick is to make it strong enough to take the abuse, but light enough not to kill FE and acceleration... ...Use your armor sparingly, as a protection, not as a first resort to just power through an obstacle.

Totally agree, my thought was bashplates over the radiator, under the engine, and then the t-case. Then abs for places that don't need "protection". I'd love to do aluminum with HDPE, but that's after I prove to myself the increases in FE... I'll save up and do it right.

Plus the heat generated by your V8 exhaust is orders of magnitude more than generated by a hypermiled Honda Civic. I don’t suggest running the belly pan under your exhaust, it is possible but it takes some serious head scratching

Yeah, this was a major source of confusion for me... I've tried finding someone that has a full belly pan on a similar vehicle, but all I can find are full on baja style racers and rock crawlers... Neither of which actually "seal" the hot air in because it's not an aero mod.

For the approach angle/air dam dilemma, one method is to use something flexible, like conveyor belt, as the dam so that it can take some abuse.

Would dropping conveyor belt on the font and side really work? Seems like you would need it to be rigid, which would defeat the purpose of using it?

Tires are going to be a compromise.

I run A/T's, I don't play in the mud so no need for anything more considering it's a daily driver.

The top part of your boat tail looks good, but I think you have the sides and bottom too steep. Consider making a small solidly mounted boat tail (that doesn’t come out past the bumper) which can’t affect offroad abilities and would have room for your spare, and then making a removable tail extension.

Bottom is definitely too steep, I'm well aware of that... Why would you think the sides are too steep? They will be the same slope as the top.

I had considered a multi-part or removable unit, but honestly... That's just one more thing to store in the back of the SUV, something I was hoping to move away from. I guess when I get to that point, I'll play with cardboard and see what I can accomplish before deciding.

The burning question in the room: What fuel economy are you getting right now?

My last 180 miles was 14.4 mpg, and actually a little better given the taller tires. It was about a 60/40 split between hwy and 10-30 mph forest service roads/trails. The new EPA combined is 14mpg. Over the course of 5 months last year, summer and winter selections, I averaged right at 14mpg.

~C