Mopar Action On-line – Tech Questions
John Winnepenninkx, Battle Mountain, NV, 2001 Dodge W150 318
We are needing to rebuild or replace a 318, 9.1 compression engine in a 2001 Dodge W150, 5 speed manual, 355 geared and throttle body fueled truck. The current original engine is high mileage, is very under powered and gets terrible gas mileage (13 mpg). What can we do in the rebuild/replace category to increase the power and gas mileage? This may be a tall order but my parts suppler, performance guy has no clue and I figured you are the best source anyway. Love the magazine!
I will guess you really meant 1991, since 2001 was a SMPI Magnum engine, not TBI. The best swap, by far, would be to find a junked ’92-’93 318 truck, or ’03 360, and swap EVERYTHING, wiring, computer, engine with SMPI, etc. The single-point injection setup is, realistically, a lost cause. There are better heads, a manifold that you could adapt, headers, etc., but even best-case, you’d be lucky to pick up a fraction of what the Magnum engine would provide (not the that Magnum was a fuel economy champ, but it is way ahead of the TBI junk, and the power and torque improvements are stunning).
If what you wrote is correct, and you’re already Magnum-equipped, headers (or ’92-’93 manifolds), a locally built 3″ exhaust, and cold air can make a noticeable improvement in power and torque, but fuel economy will only improve by about 0.5MPG — the payback period would be long.