Detroit Stationary Engine operates in a two-stroke-cycle.
(P)  Air inlet valve controlled by the governor .   (O)  Crank case.
(E)   Air passage from crank case up to cylinder (F).  (N)  The exhaust port.
(K)  Piston which moves up and down in the cylinder. (L)  Connecting rod which attaches the piston to the crank shaft (M).  (A)  Connection to fuel tank.
(B)  Fuel feeding chamber fuel is always maintained at a constant level by the float (C).   (D)  Air connection leading from the crank case to an air space   above the fuel level in the fuel chamber (B).  (I)  Is a spraying nozzle pointed into the cylinder and connected by a tube to the bottom of fuel chamber (B).  (H)  Baffle plate or deflector on top of piston. We will consider that cylinder (F) is full of fresh gas and that piston (K) is traveling upwards, closing transfer passage (E) and exhaust port (N). A vacuum is created in the crank case (O) causing air to flow through spring controlled inlet valve (P) into the crank and fuel through inlet (X) into the fuel feeding chamber. At the top of the stroke a spark occurs at the plug (G) and ignites the compressed gases in cylinder (F) causing an expansion which drives piston (K) downwards, there by putting the air in the crank case and fuel feeder under pressure. As the piston nears the end of its stroke exhaust port (N) is uncovered and the highly expanded gases shoot out this opening until atmospheric pressure is reach (there was just a cylinder full of cold gas to start with so there now remains only a small portion of this charge very highly expanded). The piston meanwhile uncovers the opening from passage (E) into the cylinder and the end of spraying nozzle (I). The compressed air in the crank case rushes into the cylinder (F) and strikes the deflector (H) which shoots it to the top of the cylinder and drives before it the remainder of the previous charge. Simultaneously with this the pressure in the fuel chamber (B) relieves itself by squirting a spray of fuel through nozzle (I). fuel also strikes deflector (H) and being in the center of the incoming air charge is instantly mixed with it to produce a perfect mixture at any and all speeds and atmospheric conditions. The inertia of the crank shaft and flywheel imparted by the first impulse carries the engine "over center" and the piston on an upward course when the fresh mixture is compressed in the cylinder, more air is drawn into the crank case and more fuel into the feeding chamber and so on.

Engine spec's