What was the most efficiently-built aircraft engine in World War II?

[Conslaw]

Also, the OP says nothing about what type of engine (ie fighter, bomber, transport, piston, axial jet, centrifugal jet, diesel, early-war, late-war, etc).

I (the OP) was deliberately vague about the type of engine. That gives you free reign to submit facts and trivia or argue away about what you think is important or just interesting.

 

[Deleted member 68059]

Again alloys matter a lot. German piston engines of the time had lifespans significantly shorter than 300hrs, I think well under 100hrs was probably typical in the late war period. That is more like 4 engines for equivalent life.

The Soviets, building essentially the exact same engine with better alloys, managed to double engine life pretty much immediately and got it up to 75hrs with a few tweaks.

Additionally if you want to make a comparison of jet v turbine engine cost you must also factor in the propeller for the piston engine.

50hours was pretty normal 1944 onwards. Its a completely wasted effort to use TBO/life to compare German or Japanese stuff to Allied. They were made under such vastly different conditions that its a meaningless metric.

 

[Reluctant Poster]

The Allison should have had a far lower production cost than the Merlin because the engine was modular and very many parts were common to many submodels. The number of parts that differ between the left and right hand rotation engines is very low - from memory one idler gear and the starter dog. The wiring harness is different but the parts that make up the harness are almost exactly the same though a few cables may be different lengths. On most, if not all, Merlins the differences are massive between left and right hand versions of the same engine so the tooling costs will be far higher.

Far lower? I doubt that. The so called modular construction any applied to the 2nd stage supercharger drive which a) is only a component (the supercharger itself does not change) and b) it was not a large part of the V-1710 production.
In the total tooling cost of the Merlin I don't see an extra gear and a revised gear case as major costs. Also there were not of lot of opposite rotation Merlins built.