Relative compression of an asymmetric internal combustion engine

Abstract

Relative compression in an asymmetric internal combustion (IC) engine is determined by measuring the change in speed of the engine crankshaft while the engine is cranked without ignition during each cylinder sub-cycle; the actual change in speed from a maximum to a minimum is measured during the compression stroke of each cylinder of the cylinder bank which is first to fire in the alternating left bank/right bank firing order of the engine, and the change in speed from a minimum to a maximum is measured during the expansion stroke of each cylinder of the second bank, such that the changes in engine speed over one engine cycle is provided as a sequence of delta speed signals associated alternately with a compression stroke and next with an expansion stroke for succeeding left bank and right bank cylinder displacements in accordance with the firing order; the delta speed signal magnitude associated with each cylinder, i.e. the compression stroke interval for the first bank of cylinders and the expansion stroke interval for the second bank of cylinders are ratio to the maximum delta value measured from among all cylinders to provide the relative compression ratio of each as a percentage of the maximum; alternately, the measured delta speed magnitude of each cylinder is ratio to the average of the delta signal values excluding the minimum delta value with each ratio limited to a unity, or 100% value.