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Gary,
This is a fun conversation.
On 6/4/2011 9:52 AM, Gary Casey wrote:
My conclusions - opinions of the disadvantages:
V-8 with reduction gear:
Heavy - about 150 pound penalty
Complex installation and systems
Slight fuel consumption penalty
Lycoming IO-720 - 600# dry weight, 400 HP.
Eagle 540 700# wet, 600 hp. A comparably sized automotive
derivative engine can easily be lighter hp for hp. Because of
internal design elements (advances in design possible because of
liquid cooling, i.e. no gas used for cooling) modern liquid cooled
engines can easily match or improve on air-cooled gas consumption.
V-8 engine direct drive turbocharged:
Heavy - about 75 pound penalty
Complex installation and systems
No information, so I can't comment. The only
one I could find was the WW1 Hispano-Suiza. Hardly relevant to the
conversation.
Rotary engine:
Very complex installation and systems
Heavy - up to 50 pound penalty
Potentially fragile apex seals
Hgh cooling drag
Noisy
Significant fuel consumption penalty increases the weight
penalty
Mazda 13B engine FWF weight 325 # all up (200
HP. I couldn't find the 20B data quickly) The equivalent engine is
the Lycoming IO-360 at 324-335 #. Sounds like a wash, or maybe a
slight win for the rotary. Yes, the rotary is slightly thirsty,
but the gap seal issue is ancient history. The newer engines have
been bulletproof.
Turbine engine:
High initial cost
High fuel consumption negates any weight savings
Amen.
Misc. opinions: The liquid-cooled V-8 dates back to about
1918 when Chevrolet built the first mass-produced one, so it's
technology is even older than the air-cooled engine's "30's
technology" that someone mentioned.
That may be true, but the resemblance between
then and now is mostly coincidental. Liquid cooling has allowed
major advances in design that are largely missing from air-cooled
engines. Now part of the blame on the air-cooled side is due to
regulatory ossification, but until completely new materials (e.g.
ceramics) come into play, there's not much to gain. Choke can't go
away, because the head of the cylinder will always be hotter than
the base. Exhaust valve troubles won't go away because the cooling
gradient between the valve and the head is so low compared to
liquid cooled engines. The basic laws of physics just don't
change. The constraints they impose limit solutions.
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