My friend wants me to work on his 86 Ranger 4x4, 2.9, 5 speed. He wants more power but wants to keep the 5 speed and functional 4 wheel drive. A 302 would probably shred the transmission, the 7.5 and maybe the transfer case. He was thinking of using a 2.3 turbo but I think he'd be better off with lower gears and either some minor mods to the 2.9 or a 4,0 ohv swap. He's going to get me the axle code so I can see if there's improvement to be made there. Opinions please, what would you do to a 2.9 to get a power increase without a complete overhaul and machining, or would a 4.0 swap be the way to go?
When you change engine size then you need to change computer and wiring, and in most cases the transmission as well
The 2.9l and 4.0l used the same trans bolt pattern which made this an easier swap, still need to swap computer and wiring, but 1986 transmission wouldn't like the extra torque, so trans change to M5OD-R1 4WD would be best, 1350 transfer case is fine to use and will bolt to the M5R1
But as said power gain is not 0 but not all that much for the work involved
V8 swap is the same work, engine/trans computer and wiring, but you can drop EFI and use carb setup so no computer and wiring, and can use V8 manual trans with V8 transfer case, could use 1350, but better to use V8 transfer case
7.5" rear end is fine to use, with any engine, its the tire size that is more of the issue with rear end size, if going over 32" diameter tires then Explorer axle would be best, it has larger axle diameter, Ranger 7.5" and 8.8" use same size axles
Turbo is better for 2WD than 4WD, on road power, 4-wheeling is not often high speed travel, it can be but.......lower RPM torque is more practical
Building the 2.9l up for more power would be an option but would still be better off changing to M5R1 transmission
And as said you can't really run a "built" 2.9l with factory computer
The 1986 computer is a "speed density" system so can't add more fuel for more power its pre-set to run the factory 2.9l
And it gets expensive to run 3rd party EFI computers
For 4WD I think the V8 would probably be the best choice, if rebuilding the 2.9l as stock, is not what he wants
"There is no replacement for displacement"