Abstract: A method of correlating a rotational position of a crankshaft to a rotational position of a camshaft includes determining a stretch value of a timing connection, which drivingly couples the crankshaft and the camshaft, and calculating a crankshaft to camshaft rotational position value indicative of the rotational position of the crankshaft with respect to the rotational position of the camshaft. The crankshaft to camshaft rotational position value is compensated based on the stretch value to provide a compensated crankshaft to camshaft rotational position value and whether the rotational position of the crankshaft correlates to the rotational position of the camshaft is determined based on the compensated crankshaft to camshaft rotational position value.

Abstract: A method of correlating a rotational position of a crankshaft to a rotational position of a camshaft includes determining a stretch value of a timing connection, which drivingly couples the crankshaft and the camshaft, and calculating a crankshaft to camshaft rotational position value indicative of the rotational position of the crankshaft with respect to the rotational position of the camshaft. The crankshaft to camshaft rotational position value is compensated based on the stretch value to provide a compensated crankshaft to camshaft rotational position value and whether the rotational position of the crankshaft correlates to the rotational position of the camshaft is determined based on the compensated crankshaft to camshaft rotational position value.

Abstract: A simplified variable intake manifold is disclosed for use with an internal combustion engine. The manifold utilizes a single valve actuator to vary the resonant frequency of a pair of plenums. The two plenums are joined by first and second communication passages of differing lengths connected to provide cross flow between two plenums. Each plenum has an inlet for receiving intake air from a throttle body and a group of runners adapted for connection with a like group of engine cylinders to direct inlet air from the plenums to combustion chambers of the cylinders. A control valve having an elongated shaft extends through the first and second communication passages and includes separate blades rotatable with the shaft to open or close the passages to provide at least three modes of tuning of the plenums. A stepper motor or other suitable device acts upon the shaft to rotate the blades within the communication passages.

Abstract: A method is described for determining the cylinder mass of air available for combustion in a crankcase scavenged, two-cycle engine, based upon the Ideal Gas Law relationship and indications of pressure, volume, and temperature of air in the crankcase chamber, at predetermined points in the engine operating cycle. This is achieved by first determining the mass of air trapped and compressed in a crankcase chamber, and thereafter, determining the residual air mass remaining in the crankcase after the transfer of air to the associated combustion chamber. Then, the actual air mass transferred to the combustion chamber is determined as a function of the difference between the trapped and residual air masses. Engine trapping efficiency can be used to correct for air leakage from the combustion chamber prior to cylinder exhaust port closure.