Abstract: Internal combustion (“IC”) engine system for high fuel conversion efficiency and low exhaust emissions, particularly although not exclusively with gaseous fuels. An IC engine operates at approximately stoichiometric (?=1) air/fuel mass ratios. A higher-than-normal compression ratio for typical stoichiometric operation is possible for the engine, due to the introduction of an inert (i.e., not chemically reactive in the combustion process) gas into the air/fuel mixture. The inert gas slows the combustion rate to avoid uncontrolled combustion rates and engine “knock.” The elevated compression ratio yields higher fuel conversion efficiency. Stoichiometric air/fuel ratio permits catalytic processing of the exhaust gas stream to reduce CO, NOx, and HC emissions via a combination of non-selective catalytic reduction process.

Abstract: Internal combustion (“IC”) engine system for high fuel conversion efficiency and low exhaust emissions, particularly although not exclusively with gaseous fuels. An IC engine operates at approximately stoichiometric (&lgr;=1) air/fuel mass ratios. A higher-than-normal compression ratio for typical stoichiometric operation is possible for the engine, due to the introduction of an inert (i.e., not chemically reactive in the combustion process) gas into the air/fuel mixture. The inert gas slows the combustion rate to avoid uncontrolled combustion rates and engine “knock.” The elevated compression ratio yields higher fuel conversion efficiency. Stoichiometric air/fuel ratio permits catalytic processing of the exhaust gas stream to reduce CO, NOx, and HC emissions via a combination of non-selective catalytic reduction process.