DETROIT SERIES DIESEL ENGINE OIL SPECS | CF-2 Two Stroke SAE 40
A two stroke diesel operates on the same 2 cycle principles as a two stroke gas engine, however the design and operational characteristics have significant differences. Two stroke diesel engines do not require a fuel-oil mixture, nor do they rely on fuel for lubrication; they feature a conventional crankcase filled with engine oil. Unlike many two cycle gas engines, a two stroke diesel requires a typical exhaust valve arrangement and thus a camshaft, although there are no intake valves and air is drawn in through the cylinder liner in the same fashion that a two cycle gas engine draws in its intake air charge.
The two stroke Detroit diesels all feature a roots type blower to create positive pressure in the cylinder during the intake stroke. This pressure creates a scavenging effect and is used to evacuate the exhaust gases from the cylinder during the combined intake and exhaust strokes. Two stroke diesel engines tend to display the following advantages:
• Higher thermal efficiency than a comparable 4 stroke engine, translating into favorable fuel efficiency.
• High power density (horsepower per unit of displacement)
• Engines are reversible and can be run in both clockwise and counterclockwise rotations (ideal for many marine applications that require a reversible engine).