Originally Posted by Brian in Tucson
Is your 4 cylinder dead? You might be ahead financially to dump the 4 cylinder truck and get what you want. Seems to me like you're looking at a whole lot of work time, down time, and expense to get a performance bump.
I agree. You'd probably be money ahead to sell the 4 cyl truck and just buy a 6 or 8 cyl truck.
Now if you could find a truck witha good drivetrain that had been rolled and the body was trashed but the engine, transmission, transfer case, drivelines, ECU, and everything that go with them was good then you might be able to do this project at an affordable price.
I don't know if you will need a new fuel pump or not. Worth looking into though. You would probably be fine with your rear end to go to a 6 cyl. And typically 4 cyl trucks have lower gearing then the bigger engine versions, so you might actually have a nice little setup if that is the case. I know in Wranglers the 4 cyl models come with 4.10 axle gearing and the 6 cyl ones can be as low as 3.07. Also, you will need to find out if your exhaust will mate up to the existing exhaust on the 4 cyl. I'm sure there are other things that will pop up too.
Is the radiator in the 4 cyl trucks the same? Will it keep up with a bigger engine?
If you don't want to sell the truck another option would be to just change the axle gears. That might give you the performance increase you're looking for. What axle gear ratio do you have now?