Boxer and un-boxer engines

["John Hertzman" <johnhertzman@xxxxxxxxxxxxx>]

Paul Misencik wrote "A 'boxer' engine refers to any horizontally-opposed
engine layout.  They are also referred to as a "flat" engine (such a Porsche
'flat six'), or a '180 degree' engine (such as Ferrari's '180 degree V12' -
but this designation is far less common)."

James Tyson wrote "Paul M.'s post indicated that the terms 'boxer' and 'flat'
were synonymous.I have been laboring under the impression for some time that a
flat,or 180 degree engine doesn't have to be  an opposed or boxer engine.Could
someone please educate me on this subject?"

In Alfaspeak (or at least in Fusi's vocabulary) in a boxer the approximately
opposite pistons are on separate throws of the crank, both moving toward or
away from TDC and BDC at the same times, as on the Alfasud and on the 33 TT 12
("boxer a 12 cilindri orizzontali contraposti"). Both the flat twelve tipo 512
of 1940 and the flat twelve tipo 160 0f 1952 had the conrods of the
approximately opposite pistons on the same throw of the crank, one piston
moving 'down' while the other moved 'up', analogous to the action and layout
of the 135 degree V16 tipo 152 also of 1940 or the 90 degree V8 33/2 of 1967.
By this analogy the 512 and 160 were 180 degree Vs, quite distinct from
"boxers". I assume (but don't know) that this distinction holds in German
usage, and applies similarly to the Ferrari '180 degree V12'.

This skirts the whole question of other opposed-piston layouts, like the
two-stroke Fiat GP engine of the late twenties, or the Junkers Jumo diesel -
or the Gobron-Brillie - enuf is enuf.

Enjoy,

John H., Raleigh N.C.
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