Sneak Peak! Ford’s “Bobcat” Dual Fuel Engine
by Mike Levine. A radical twin-fuel engine from Ford, code-named “Bobcat,” that variably blends gasoline and ethanol on demand to realize diesel-like performance continues to make steady progress in its development, according to presentations made by the automaker to the Department of Energy and Society of Automotive Engineers in April. The presentations also provide a first look at the engine’s architecture and make some remarkable claims about “E85-optimized” engine efficiency versus size.
The Bobcat engine starts with a small turbocharged engine with separate gasoline and ethanol (E85) fuel injectors for each cylinder. The gasoline system mixes fuel and air in the motor’s intake manifold using port injection. The second system uses direct injection to introduce small amounts of ethanol directly into the combustion chamber to control premature detonation, or knock, which results from the high temperature and pressure of a turbocharged engine. The ethanol prevents knock by cooling the air/fuel mixture until the engine is ready for combustion. With knock suppressed, the compression ratio can be increased.
Ford’s engineering partner, Ethanol Boosting Systems, LLC of Cambridge, Mass., has trademarked the term “DI Octane Boost” to describe the process; the direct injection of ethanol effectively increases the octane of regular gasoline from 88-91 octane to more than 150 octane. READ MORE and MORE