I'm thinking of a belly pan for the Ranger. The engine bay and cab look pretty straight forward. Mostly a question of leaving access to maintance points. I could use some advice for the bed area.
The fuel tank and, of course, the driveshaft and axle hang below the frame rails. Originally, I was thinking of having the pan slope down over the tank, and direct air down over the axle. Maybe even mount airtabs on the edge of it to help the flow over the axle, spare, and rear bumper. But know I'm thinking of mounting a plow in front of them. A dam with more angle to direct air out from under the truck. I could even extend it to direct air past the rear wheels.
The slope pressing the air down, may cause a pressure build up under the axle, and perhaps reduce tire traction. At least to my untrained thinking. Of course, the air going out the side with the plow may be just as bad in some way. So, thoughts on what I should try? If it's the plow, should it be pointy or bow shaped, and what angle would be best?
I've been having similar thoughts about my S10 with similar problems, waiting to start getting paychecks from the new job and better weather to work on it. I was going to go with a bow-shaped dam in front of the rear axle and continue that distance from the frame with a diffuser of sorts angling upward toward the bumper.... see if it does anything at all.
as for accessing things, what material are you planning on using and how are you planning on attatching it? I figured aluminum screen near exhaust components and roof flashing for the rest. or flashing all around. sheet metal flashing also allows me to crimp 'ribs' to channel air out from underneath. still working on how to attach it tho. Idea I had while typing... it's a truck, built a frame that clamps onto the trucks frame from underneath. maybe a door or something to change the oil and anything else underneath just drop the frame off the belly...hmmmm
Another aspect I've been looking at is the enormous cavern of a wheel well on the truck. just covering them from the side has had poor results in large wheel wells from other people, I was thinking of an conveyor belt material scraper on the rear edge to keep are caught up in the tire out of the wheel well.
There are just so very many ways to improve the aerodynamics of trucks. there's no end to the fun and ideas you can have.
1991 Toyota Pickup 22R-E 2.4 I4/5 speed
1990 Toyota Cressida 7M-GE 3.0 I6/5-speed manual
mechanic, carpenter, stagehand, rigger, and know-it-all smartass
"You don't get to judge me for how I fix what you break"