Originally Posted by
Andy_RR
I googled "IO-550 SFC" and this came up on the first line:
https://summitaviationmfg.com/wp-con...-TI_Engine.pdf
It quotes a 0.385 lb/hp.h which is 234g/kW.h although it may have got the best economy and best power figures switched on page 3. These numbers are, however, typical of what I've seen quoted around the traps for many years. As far as BMW diesels doing 198g/kW.h that's a very best-point number and there would be some celebration in the engineering office about it. Some of the old VW PD diesels are sub-200 but it's quite difficult to do and even more difficult to spread out across a useable area. The fuel consumption you see in the day-to-day use of a car is waaaay worse than these numbers, especially on a gasoline engine. If you could cruise at a steady 100km/h at 200g/kWh in a modern car you'd be seeing 3.5-3.8L/100km That's not typical of anything I know of.
Thanks for that. I never realized how efficient they have managed to make these air-cooled flat sixes now. Indeed Google works in mysterious ways... BTW, the BMW engine whose figures I used was 2007 vintage, there have been significant improvements in sensor and ECU responses since then. I guess it depends, how light and how clean the car is when consumptions are being compared.
Nevertheless, it will be interesting to see how the diesel in that Raptor aircraft works - form memory, they're saying something like 8gph in cruise at FL 210 and 230 KTAS. If it works even half as well as claimed it will be a game changer.