LuPi wrote: .......
Aero engines have 1,000hr TBO and redundant systems. Recently it's been suggested that automotive engines might actually have greater reliability with certain engines getting 4,000+ hrs before failure. ......
every flight needs full power and rpm, no car will give 4000 hrs like that
and there are no parking places in the sky
most aero engines eg Lycoming have a 2000 hr TBO which is usually extended 'on condition' to 2800 hrs or more
TBO extensions are based on condition monitoring and the extent of the operator's inspection and maintenance procedures
for 60+ years car or related engines have been tried and have not been taken up
eg amateur VW Beetle, Civic, Buick/Oldsmobile V8, US iron smallblock and bigblock V8s, V12 Jaguar etc
and serious efforts from Porsche, Honda, Renault etc
for aviation you need individual cylinders and heads (so pushrods and air cooling)
so when there's low compression on 1 cylinder it can be easily cured by ring unsticking or a valve grind
costs $250, and saves $25000
that's why they had all those radial engines, and still have all those Flat 4s and Flat 6s
an aero engine is only as good as its ability to turn power efficiently into thrust
so a reduction mechanism (or avoiding such) is a dominant design factor
eg avoiding it by designing for low rpm via a low bore:stroke ratio
a Magnesium alloy V4 sounds like a good idea
Flat engines can impede the pilot's view, make a big hole in the air, and are ugly
we only got them by accident (a 30s depression-era cheapie cast in 1 piece by being a sidevalve)
