Abstract: Means and method of substantially increasing the efficiency of a spark ignition Otto cycle engine. This is done by increasing the stroke length of the pistons and reducing the amount of air (or fuel/air mixture) by means other than the throttle plate taken in on the intake stroke. The amount of air or fuel/air mixture taken in is that which creates the same conditions in the combustion chamber at the conclusion of the compression stroke as exist in prior art engines used for the same application. The advantage arises from the increase in the length of the power stroke; this extracts more energy from the combustion gases before they are removed on the exhaust stroke and it also increases the torque of the engine as it is well known that torque is a function of stroke length. Extracting more energy from the combustion gases also reduces the amount of heat transferred to the engine block, thereby reducing the load on the cooling system.