Towards 40% efficiency with BMEP exceeding 30 bar in directly injected, turbocharged, spark ignition ethanol engines

Current flexi fuel gasoline and ethanol engines have efficiencies generally lower than dedicated gasoline engines. Considering ethanol has a few advantages with reference to gasoline, namely the higher octane number and the larger heat of vaporization, the paper explores the potentials of dedicated pure ethanol engines using the most advanced techniques available for gasoline engines, specifically direct injection, turbo charging and variable valve actuation. Computations are performed with state-of-the-art, well validated, engine and vehicle performance simulations packages, generally accepted to produce accurate results when targeting major trends in engine developments. The higher compression ratio and the higher boost permitted by ethanol allows larger than gasoline top engine brake thermal efficiencies and peak power and torque, while the variable valve actuation produces smaller penalties in efficiency changing the load than in conventional throttle controlled engines.