Development of a high efficiency dilute gasoline engine
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Development of a High Efficiency Dilute Gasoline Engine (HEDGE) and control system for use in the Challenge X design competition encompasses the body of this work. The HEDGE concept embodies running an engine on gasoline at Diesel-like compression ratios. This is accomplished through extreme amounts of Exhaust Gas Recirculation to prevent knock. In addition, a high energy ignition system is necessary to ensure cylinder combustion due to the high dilution. This high energy ignition system took the form of a Diesel pilot injection. A 2005 1.9L Euro IV Diesel engine, was modified for use in HEDGE operation by re-routing the Exhaust Gas Recirculation pre-compressor instead of post-compressor for increased flow and adding gasoline port fuel injectors. Simultaneously, a fully programmable Motohawk engine control system was developed and implemented to allow full control of all engine functions including multiple injections from both gasoline and Diesel fuel injectors. During the course of engine development, cylinder 4 of the initial engine failed due to a loss of compression. Failure analysis of cylinder 4 determined that the damage was caused by excessive cylinder temperature and pressure caused by a failed Diesel injector. Several engine protection systems were implemented to protect the second engine. Engine dynamometer testing was conducted on the second engine in single Diesel injection pulse operating mode and resulting emissions and fuel consumption data were compared to stock engine performance information. Testing of HEDGE operation was not conducted due to time constraints related to the project. Baseline Diesel operation data will be used for comparison of HEDGE operation in the future.