The need for a natural gas conversion kit for heavy-duty engines which provides equivalent gasoline performance as well as acceptable exhaust emissions has prompted the use of turbocharged lean-burn engine technology. Turbocharged lean-burn strategy allows operation which meets current heavy-duty emission requirements without the need for a catalytic converter. To insure proper fuel distribution during lean-burn operation, the system includes multi-point sequential fuel injection, fully mapped lambda control, deceleration fuel cut-off, part load cylinder deactivation, and fuel charge stratification.
This paper documents the design and development of a General Motors turbocharged, sequential fuel injected, leanburn natural gas engine based on the 4.3L truck engine. Presented as results are the schematics of the overall fuel control system, the benefit of turbocharged lean-burn operation, the basic control algorithms, power comparison between compressed natural gas (CNG) and gasoline, and heavy-duty transient exhaust emissions test data. Transient dynamometer and field durability testing results are also presented