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What is changed to make a diesel-engine work in an airplane?

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Frank N. O.:
I know a bit about passengercar and truck (roadtrain) diesel engines and after seeing that diesels are now proving to work great for GA planes like in passengercars (in Europe at least) then I'd like to know details on what is changed to make them work in planes. I read that the 1.7L Thielert is based on a Mercedes-Benz car-engine and that would probably be the one used in the 1-box A-Class since they have a 1.7 but that's a watercooled engine with electronic fuel-injection, does it still have this in the aviation version (not that I can imagine it would work without it)? And does the diesel have problems with ignition when it comes into thinner air or does the turbocharger eliminate that problem like turbonormalizing in a gasoline aviation engine? How much does a diesel engine with watercooling weigh vs a aircooled big displacement gasoline aviation engine? Even a small 4-cylinder Cessna engine is around 5.9L if I remember correctly (the designation number is the CID) and is it a problem that the dieselengines are inline and not boxers (horizontally opposed)? Now for a probably dumb question: Isn't it a great benefit that diesels don't use ignition systems both in terms of reliability and maintenance?

Frank

Gulfstream Driver:
About the only thing I know about diesels is they don't have spark plugs.   :D

Frank N. O.:
LOL, nope but they do have glow-plugs to heat up the diesel when it's starting cold, or at least my dad's 84 Ford Fiesta 1.6 Diesel did (and that was a new-generation engine back then, like the VW TDI engines were about 10 years later and of course also the common-rail system as well). My dad averaged 58 miles per US gallon fuel economy with 54 naturally aspirated hp pulling 1764lbs, The 14.1L 420hp intercooled V8 turbodiesel in the 22 wheeled 47.5 ton Scania R-142H 6x2 roadtrain he drove was a different story however, that was more like 5 mpg but then again, it could carry over 33 tons of cargo.

Frank

fireflyr:
Germany used some two-stroke diesels  (Jumo diesels) in the 30s and 40s, they were quite complex in spite of not having a valve train

With fuel becoming so expensive, I believe Thielert is on the right track.   A diesel's power band would be well suited for aircraft work (low RPM and high torque) and the ability to more precisely meter fuel gives them better economy, just look at the performance versus fuel use of the Diamond Twin. :)

Frank N. O.:
You know, BMW also makes some high-power diesels, like a 3L straight-6 24V DOHC with 230hp and 450Nm (in std. car-form with ultra-tight emission std's). VAG of course is also a big player in the high-tech diesel-market (Volkswagen Audi Group). Just imagine a plane with a straight-6 BMW Turbo Diesel :D I'm sure all here know what BMW started as right? And BMW's may be show-off cars but they do excell in engine-making both in terms of performance and quality from what I hear, my late uncle also always drove old BMW's and they just lasted hundreds of thousands of km's and BMW was the only one to attempt to make the engine demanded by McLaren for the F1 streetcar since the quality, specifications and power output demanded was simply thrue the roof, but BMW did it and with more than needed power that engine ran extremely reliable even in racetrim even though the F1 was actually strictly planned as a streetcar. Now if that also goes for the diesels then it could be cool flying :D

Frank

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