mastic wrote:
>
> >> And some of the operations are happening simultaneously.
> >
> >There is one very efficient 2-stroke variant that does have separate and
> >distinct intake, compression, combustion and exhaust functions - the
> >opposed-piston 2-stroke diesel with the pistons driven by cams, not
> >crankshafts.
> >
> >As the pistons move apart (power), the exhaust port is uncovered first by
> >one piston (exhaust) and then the intake is opened by the other piston so
> >high pressure air from the supercharger can scavenge the last bits of
> >exhaust gas from the space between the pistons. After the cylinder is
> >scavenged, the first piston closes the exhaust port leaving the intake port
> >open so the supercharger can charge the cylinder with air (intake). Then
> >both pistons move together closing the intake port (compression). Fuel is
> >injected directly into the space between the pistons which forms a spherical
> >combustion chamber (ignition). The cams are designed to optimize the timing
> >and duration of the port openings as well as contour the compression and
> >power strokes.
> >
> >This design makes extreme demands on metallurgy and lubricants so is just
> >now becoming practical.
> >
> >Bill Daniels
>
> The British Deltic diesel engine use opposed pistons with normal
> crankshafts, three banks of cylinders, three crankshafts in a
> triangular lay out. A very compact light weight engine. Large HP
> engines something like 1500 - 3000 HP, used in boats and railway
> locomotives.

That was a good way to stuff 2,500 high-hour horsepower into a volume
only 6' wide, 9' long and 7' tall back then. Not as efficient as modern
designs, but way ahead of the curve back then. Note, the Deltic was a
direct-drive locomotive power system.

JazzMan
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