Abstract: The present invention relates to an uneven cylinder displacement arrangement of a multi-stage variable displacement engine. By arranging a plurality of cylinders of at least two different cylinder bores or at least two different strokes in an engine while grouping the plural cylinders into at least two cylinder groups, e.g. grouping odd-numbered cylinders in an ignition sequence of the engine into a first group while grouping even-numbered cylinders in an ignition sequence of the engine into a second group, the engine is enabled to have multi-stage displacement capability adapted to various operation speeds for reducing fuel consumption since the displacement of the engine can be varied by using the ignition sequence to control and select which groups are to be ignited for matching the current load of the engine.