Patent ID: 7314033

Claim:
A turbocharged, spark ignition engine which uses port fuel injection of gasoline from a first source in addition to direct fuel injection of liquid denatured ethanol from a second source comprising: a spark ignition engine; a turbocharger; means for port fuel injection of gasoline from the first source; means for direct fuel injection of liquid denatured ethanol from the second source; wherein during part of engine operating time, the engine is powered both by gasoline that is port fuel injected and ethanol that is directly injected; and wherein during part of the operating time the instantaneous ethanol energy fraction is at least 20%; and wherein the ethanol is directly injected in an amount such that the evaporative cooling of the fuel/air charge by the directly injected ethanol combined with the higher octane number of the ethanol enhances the octane number by at least 20 octane numbers; and a fuel management system including a microprocessor which increases the ethanol energy fraction with increasing torque so that it is sufficient to prevent knock; and wherein the fuel management system uses closed loop control with information from a knock detector to vary the ethanol energy fraction when the instantaneous ethanol fraction is at least 20%; and wherein the fuel management system minimizes the ethanol use by using information from the knock detector; and wherein the turbocharged direct injection spark ignition engine is operated at a substantially stochiometric air/fuel ratio; and wherein the fuel management microprocessor uses information about the ethanol level in the second source to control the turbocharger; and wherein the turbocharging is eliminated or reduced when there is no ethanol in the second source; and wherein a vehicle with this spark ignition engine can be operated on port fuel injected gasoline alone without knock.