How to Improve 2003 Ford F250 V10 Gas Mileage

by Richard Rowe
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The 1990s were an important time for V-10 engines, marking a resurgence of a configuration that had once been the sole providence of supercars and foreign exotics. Ford's Modular engine, introduced in 1991, has lived up to its name in spades by expanding from a milquetoast 281 cubic inch V-8 all the way to the thumping 413 cubic inch Triton V-10. While undoubtedly powerful and versatile, the Triton isn't exactly the fuel economy champ of its family, especially when pared with the massive F-250 chassis. Still, boosting your truck's road-thriftiness need not necessarily mean killing its fun factor.

Step 1

Install a rear-mount twin-turbo system by purchasing the universal components and fabricating the rest yourself. Yes, adding a turbo to increase fuel mileage may seem a little backward, but you'll see the logic in a moment. Obviously, fabricating a twin-turbo system is beyond the scope of a 700-word article, so if you don't have sufficient fabrication skills then enlist the services of someone who does. Start with a low-boost turbo system engineered for a 4.6-liter modular Mustang and make it fit by installing longer turbo-to-engine plumbing.

Step 2

Install numerically-lower rear axle gearing, in the range of about 2.2 to 2.25-to-1. This axle gearing is the key to keeping your newly-turbocharged engine in its key efficiency range. The lower gearing will keep rpm down while allowing you to modulate the engine's required power output by adjusting turbo boost. In this way, the turbos act as sort of a variable-displacement mechanism, pumping only as much air into the engine as it needs to maintain a given speed with a given load.

Step 3

Install a set of shorter, skinnier tires on the front and rear. The F-250 comes stock with 16 by 7 inch rims and LT235/85R E-rated tires; go for a set of LT180/70 tires for a 2.5-inch drop in ride height. Select a set of tires with a very hard, long-wearing rubber compound for reduced rolling resistance and increased mpg. If you have dual rear tires, dump then and use a set of singles. The shorter tires will numerically increase the effective final drive ratio by about 17 percent, which is part of the reason for the higher gearing from Step 2.

Step 4

Strip as much weight as possible from the truck. At 5,600 pounds, your truck is never going to be a Lotus, but every pound you can take off will decrease the amount of boost you'll need to maintain the performance you're after. You could rip the 4WD axle, transfer case and running gear out to save a few pounds and reduce rolling resistance, but you'll regret it with skinny tires and 500-plus horsepower of turbocharged Triton on tap.

Step 5

Enhance your truck's aerodynamics by installing a set of performance lowering springs, stiffer shocks, a Tonneau cover and a full sheet-metal "belly pan" to cover the bottom of your vehicle's chassis. An air dam installed under the front bumper will keep drag and lift-inducing air out from under the truck, but you'll need to install a vented hood and fenders to evacuate engine heat. The end result will be greater fuel efficiency and stability at highway speeds. The F-250 comes with 8.3 inches of ground clearance stock, so even after installing the 2.5-inch shorter tires you can still lower it by about two inches while maintaining a reasonable four inches of ground clearance.

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