Marine Diesel Engine Specs

• Marine diesel engines are designed for ships and boats. They are very similar to the diesel engines found in trucks, except everything about them is on a substantially larger scale. They also tend to be two-stroke engines, while truck engines are four-stroke.

Fuel Injection

• Diesel engines rely on pressure. As opposed to standard fuel engines, they do not have spark plugs. Rather, they pressurize the diesel and the air in the cylinder to heat it to the point of ignition. This means that an important specification of a marine diesel engine is the presence of a fuel injector.

  The fuel injector pressurizes diesel and makes it into a fine spray. It does this through a spring-loaded system. A spring is held flush against the opening between the injector and the piston, and fuel is pumped in from the side. As the pressure rises, the spring pushes up, eventually releasing the diesel and dropping down again. This cycle repeats itself as long as the engine runs.

Pistons

• The pistons are made of steel that is alloyed with chromium and molybdenum to increase its strength. This is only necessary on the top piece, which is subject to the heat and pressure of constant explosions. The bottom half, whose only purpose is to move the crankshaft, is made of cast iron.

Crankshaft and Camshaft

• The crankshaft is one of the larger parts of the engine, sometimes weighing up to 300 tons. It is attached to the pistons, but turns in opposition to them. Essentially, as each piston moves up or down, it moves the crankshaft in a circular motion. This circular motion is then used to power the ship by attaching the crankshaft to the propellers.

  The camshaft is equally important. It is attached to the crankshaft and moves with it. It operates the fuel pump and exhaust valves, pulling fuel in on the downstroke and pushing exhaust out on the upstroke. It is driven by either a gear or chain drive to synchronize its movements with the crankshaft.