High performance, low emission engines, multiple cylinder engines and operating methods

A method of operating a piston engine comprising, in a camless engine:

• at or near the end of a power stroke, opening and then closing the exhaust valve of a combustion cylinder to trap a predetermined amount of exhaust gas in the combustion cylinder;
• injecting fuel into the combustion chamber during the following compression stroke soon after the exhaust valve is closed;
• injecting air into the combustion cylinder as the piston approaches top dead center and before compression ignition;
• the amount of exhaust gas trapped in the combustion cylinder and the amount of air injected as the piston approaches top dead center being controlled to obtain compression ignition at or near top dead center without reaching NOX formation temperatures in the combustion cylinder;
• and,
• injecting air into the combustion cylinder after ignition and after the piston has passed top dead center to sustain combustion without reaching NOX formation temperatures and without injection of more fuel;
• the air injection air into the cylinder prior to the end of the compression stroke being at approximately the same engine cylinder pressure as the air injection to sustain combustion of the fuel during the power stroke following the compression stoke;
• whereby the air injections may be from a source of pressurized air at a single pressure.

A method of operating a piston engine comprising:

• at or near the end of a power stroke, opening and then closing the exhaust valve of a combustion cylinder to trap a predetermined amount of exhaust gas in the combustion cylinder;
• injecting fuel into the combustion chamber during the following compression stroke soon after the exhaust valve is closed, the amount of fuel injected being the total amount of fuel to be injected during the compression stroke and the following power stroke;
• injecting air into the combustion cylinder as the piston approaches top dead center and before compression ignition;
• the amount of exhaust gas trapped in the combustion cylinder and the amount of air injected as the piston approaches top dead center being controlled to obtain compression ignition at or near top dead center without reaching NOX formation temperatures in the combustion cylinder;
• and,
• injecting air into the combustion cylinder after ignition and after the piston has passed top dead center to sustain combustion without reaching NOX formation temperatures;
• the air injection air into the cylinder prior to the end of the compression stroke being at approximately the same engine cylinder pressure as the air injection to sustain combustion of the fuel during the power stroke following the compression stoke;
• whereby the air injections may be from a source of pressurized air at a single pressure.