Ford is working on a twin-fuel turbocharged engine that could deliver diesel-like performance without the diesel engine’s hefty price premium. The engine, code-named “Bobcat,” variably blends gasoline and ethanol (E85) for better fuel economy and extra power.
The Bobcat is essentially a small turbocharged engine with separate gasoline and ethanol fuel injectors on each cylinder. First, the gasoline system mixes air and fuel in the intake manifold using port injection. Next, the ethanol system uses direct injection to spray small amounts of ethanol into the combustion chamber to prevent premature detonation, or knock, which results from the high temperature and pressure of a turbocharged engine. The ethanol cools the air/fuel mixture until the engine is ready to ignite it. This suppresses knock which enables the compression ratio to be increased.
Ford is working with a company called Ethanol Boosting Systems which has trademarked the term “DI Octane Boost” to describe this method. The term was chosen because the ethanol direct injection process increases the octane of regular gasoline from 88-91 octane to more than 150 octane.
The engine varies the ratio of gasoline and ethanol based on the load conditions of the engine. With a low-to-medium load on the engine, only gasoline may be required. When the load increases, the direct injected ethanol would be added to prevent knock. A 5.0-liter V-8 Bobcat engine used for illustration could potentially produce 500 hp and 750 lb-ft of torque using this technology.
A vehicle equipped with the Bobcat engine would require separate tanks for E85 and regular unleaded gasoline. According to PickupTrucks.com, Ford’s leaked information presented a comparison between a 5.0-liter Bobcat V-8 with a 10-gallon E85 tank and 26-gallon gas tank compared to a current Ford F-150 with a 5.4-liter V-8 and 26-gallon gas tank. Under mild driving conditions, the Bobcat engine would need to be refueled with regular gasoline every 528 miles and refueled with ethanol every 20,000 miles. Under these same conditions the 5.4-liter would have to be refueled every 486 miles.
With the latest Corporate Average Fuel Economy requirement of 35.5 mpg for cars and 30 mpg for light trucks coming in 2016, the new Bobcat engine could be one of the keys in Ford’s future engine lineup. Right now the engine is being tested in labs and computer simulations, but the company is planning to test Bobcat the engine in an F-series pickup for the first time later this year.