Abstract: A combustion engine having a combustion chamber with a side port in a sidewall thereof interconnecting the combustion chamber with a side manifold. The side port is positioned between about 25% and about 75% of the stroke length from the bottom dead center position of the pistons. The engine includes a fluid injection system which provides an alcohol-water mixture to the side manifold to maintain the manifold at an elevated pressure. The pressure manifold is heated to provide for expansion of the fluids provided thereto and is readily removable to allow for normal functioning of the engine.