Piston engine with selectable firing order

An internal combustion engine comprising:

• a crankcase;
• a crankshaft including,
• a plurality of axial center pins rotatably coupled to the crankcase,
• a plurality of big pins offset from the center pins, and
• a plurality of webs coupling the big pins to the center pins;
• a cylinder block coupled to the crankcase and including a plurality of cylinders;
• a plurality of pistons each disposed within a respective one of the cylinders and coupled to a respective one of the big pins by a connecting rod;
• a head coupled to the cylinder block and including, for each of the cylinders,
• an intake valve,
• an exhaust valve, and
• means for providing fuel into the cylinder;
• means for controlling timing of operation of at least one of (i) the valves, and (ii) the means for providing fuel, of at least one of the cylinders;
• and
• means, coupled to the means for controlling timing, for causing a change from a first firing order to a second firing order.

A method of switching from a first firing order to a second firing order in a multi-cylinder internal combustion reciprocating piston engine which operates according to a four-stroke cycle, wherein the engine includes a crankshaft having a plurality of offset big pins to which respective pistons are coupled by respective connecting rods, and, for each cylinder, an intake valve, an exhaust valve, and one of a carburetor and a fuel injector, and wherein the method comprises:

• receiving a firing order switch trigger;
• for at least one of the cylinders, in response to the firing order switch trigger,
• waiting until a predetermined position of the crankshaft, then
• shifting timing of operation of the cylinder's valves by substantially 360° of rotation of the crankshaft, such that, substantially at the end of a current stroke, operation of the cylinder's valves skips two strokes of the four-stroke cycle.

A method of operating an internal combustion engine according to a four-stroke cycle including an intake stroke, a compression stroke, a power stroke, and an exhaust stroke, the engine including (i) a crankshaft which has a plurality of big pins, (ii) a plurality of pistons coupled to the crankshaft, (iii) a plurality of cylinders within which respective pistons are reciprocatingly disposed, and (iv) intake and exhaust valves for each cylinder, wherein the method comprises:

• (1) during a first time, for each 720° of rotation of the crankshaft including two 360° rotations,
• for each cylinder, synchronizing operation of its valves to a selected one of the 360° rotations such that each cylinder operates according to the four-stroke cycle and the multiple cylinders operate according to a first firing order;
• (2) receiving a switch trigger;
• and
• (3) in response to the switch trigger, during a second time, for each 720° of rotation of the crankshaft,
• for each of at least one of the cylinders, synchronizing operation of its valves to the other of the 360° rotations such that multiple cylinders operate according to a second firing order.