On Wed, 10 Sep 2003 12:17:57 -0500, Jon Elson
wrote:



Jim Stewart wrote:

Bob Swinney wrote:

I make no claim to knowledge in thermodynamics - but - I think the
increase
in efficiency is partly due to the increase in size. Larger objects
lose a
lesser amount of heat (energy) than smaller ones. Common steam
engines are
also more efficient in the larger sizes.


More specifically, size and speed. By turning slowly, the combustion
gasses have more time to expand and convert heat to mechanical
force.

But, they also have more time to conduct heat to the cylinder walls, head
and piston. The extensive cooling of the piston makes me think they are
running this engine VERY hot, with a higher compression ratio (including
the supercharging) than usual. Notice also the extremely long stroke,
2.58 times the bore.

Jon

Which brings to my mind another question - being diesel and with a 3'
bore and 8' stroke the compressions pressures have got to be large -
so the injection pump would have to put out some high pressure to be
able to spray into the combustion chamber. The injection pump(s) for
this thing have gotta be pretty impressive also.
Ken.