The following specifications are for the production engine and its prototypes, known as the model DR-980:[11] Type 4-stroke cycle diesel Cylinders 9--static radial configuration Cooling Air Fuel injection Directly into cylinders at a pressure of 6000 psi Valves Poppet type, one per cylinder Ignition Compression--glow plugs for starting--air compression 500 psi at 1000 deg. F. Fuel Distillate or "furnace oil" Horsepower 225 at 1950 rpm Bore and stroke 4-13/16 in. x 6 in. Compression ratio 16:1--maximum combustion pressure 1500 psi Displacement 982 cu in. Weight 510 lb without propeller hub Weight-horsepower ratio 2.26 lb hp Where manufactured U.S.A. Fuel consumption .46 lb per hp/hr at full power Fuel consumption .40 lb per hp/hr at cruising Oil consumption .04 lb per hp/hr Outside diameter 45-11/16 in. Overall length 36-3/4 in. Optional accessories Starter--Eclipse electric inertia; 6 volts. Special series no. 7 Generator--Eclipse type G-1; 6 volts [Illustration: Figure 17.--Longitudinal cross section, Packard diesel engine DR-980. (Smithsonian photo A48845.)] [Illustration: Figure 18.--Transverse cross section, Packard diesel engine DR-980. (Smithsonian photo A48847.)] [Illustration: Figure 19.--Right side view of engine, showing accessories; Packard Motor Car Co. 50-hour test, 1930. A, starter; B, oil filter. (Smithsonian photo A48323.)] [Illustration: Figure 20.--Rear left view of engine, showing accessories, U.S. Navy 50-hour test, 1931. Barrel valve type venturi throttles. A, starter; B, oil filter; C, fuel circulating pump; D, generator. (Smithsonian photo A48324C.)] Operating Cycles The sequences of operation of a Packard diesel engine compared with those of a 4-stroke cycle gasoline engine are illustrated in figure 21. [Illustration: =Brief Analysis of Action in a Four-Cycle Gasoline Engine= _Mixture of air and gasoline enters cylinder from carburetor._ _Mixture is compressed into smaller volume by piston moving upward._ _An electric spark ignites the compressed mixture causing it to explode._ _Combustion heat increases the cylinder pressure forcing piston downward._ _Momentum carries piston upward which pushes burnt gases out through the exhaust valve._ =Similar Action in the Packard-Diesel Aircraft Engine= _Atmospheric air only, enters cylinder through single valve._ _Air is so greatly compressed by upward moving piston that it reaches temperature of 1000 deg. F._ _Just before piston is at dead center fuel oil is sprayed into cylinder and spontaneously ignited._