Scary
Guru
There has been some comment on the relative inefficiency of the two stroke Detroit when compared to a 4 stroke diesel engine. I'm wondering if there may be some confusion based on the difference between a two stroke gas engine and a four stroke gas engine. Modern electronically controlled four stroke/ two stroke gas or diesel engines are more efficient than there mechanically controlled ancestors. However are the older mechanically controlled 4 strokes cleaner and more fuel efficient than the two stroke Detroit? If so why and how do you know this. When I look at the difference what I see is an engine firing twice as often burning the same fuel controlled by mechanical injection into the combustion chamber same as the 4 stroke diesel. The difference being that the intake charge is through ports in the cylinder liner at the bottom of the piston stroke rather than valves in the head. A roots blower pressurizes the air in a plenum that charges the cylinder through these ports. This allows the 4 valves in the head to be exhaust valves. The expanding hot gases from combustion escape through these valves aided by the fresh charge from the pressurized combustion air entering through the intake ports. These engines fire on every revolution thus twice as often as a four stroke. MTU continues to manufacture these engines for military and industrial use . Over 3,500,000 of these engines were built between 1940 and now with an estimated 300,000 still at work. So my question is this, are they really less efficient? We know they are very durable. Are we comparing the efficient modern electronically controlled diesel with old technology? Is the Lehman , Volvo , Perkins, more efficient than the Detroit?