LP-Powered 2008 Ford F-150 Roush Truck

Rex Roy
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I get in, turn the key, and suddenly I'm inexplicably dying to have a barbeque. It's a feeling I can't shake because I'm driving an otherwise stock 2008 Ford F-150 that's powered by liquid propane (LP), that ubiquitous grill fuel. (Methinks the column shifter should be a spatula.)

Our subject F-150 features fuel-system modifications developed by Roush Industries, the same folks who build all manner of high-performance Mustangs and contributed engineering expertise to the Ford GT supercar. This particular truck is designed for fleets that have easy access to propane, thus nullifying concerns over having to daisy chain a series of Rhino tanks. Although the current customer demographic includes municipal and commercial fleets, the push to run vehicles on something other than gasoline is likely to entice private citizens to consider propane in the coming years.

The Roush Conversion
Roush's offering is serious, as it matches the significant capabilities of the gasoline-fired F-series when it comes to crankshaft horsepower as well as payload and towing. Roush currently offers LP conversions for just about any 2008 F-150 powered by the 5.4-liter Triton V-8 engine, which is available in trucks offering three cab choices, three bed lengths, and five trim levels.

The conversion's focus is the fuel system. Changes begin with storage; Roush offers two fuel tank sizes, a 25-gallon bagel-shaped Toroidal holding cell that occupies the same location as the truck's discarded gasoline tank and a larger 59-gallon drum-type unit that fits in the bed. According to Roush, most customers go for the larger tank because of its 500-plus-mile range and simply deal with the reduced bed volume.

Forward of the tank, Roush replaces everything fuel-related, including custom billet fuel rails that carry liquid propane to custom injectors. Given LP's natural tendency to vaporize when not under pressure, the fuel atomizes as it exits the injector, creating an easy-to-combust charge.

To take advantage of propane's higher octane equivalency (99 to 112 octane R/M, depending on the refiner), Roush engineers reprogrammed the F-150's engine control module. The resulting output matches the gasoline-powered F-150's 300 hp and 365 lb-ft of torque. Given this consistency, it's no surprise that everything inside the engine remains stock and fully covered under Ford's factory warranty. Roush backs its hardware separately.

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