Originally Posted By: Gannet167
a typical new engine in a light, general aviation aircraft is really from a 1930's design and engineering mentality. They're huge displacement engines making low amounts of power. Compared to the amazing advances in automotive engines and turbine engines, the piston aircraft world has a long, long way to come to even reach 1970's technology.
the future may be with these diesel conversions.
Aviation piston engines achieve better BSFC numbers than many "Modern" engines, including diesels. 0.38 Lb/HP/Hr is a typical number for a modern Lycoming in cruise configuration. The Toyota Prius engine cannot achieve these numbers.
Low RPM, lower piston ring swept area numbers, large displacement and air cooling all contribute to excellent BSFC numbers. Couple the design advantages of "aircraft" engines with some modern technology such as electronic controls and efficiency numbers improve even more. It is not uncommon to see 200 to 320 cubic inch engines achieving more than 40 miles per gallon at speeds over 200MPH. Let's see your "modern" car do that!
To install an engine with "modern" technology would result in a loss of range, in most cases. Consider a typical Honda 4 valve, double overhead cam, high RPM engine as an example. The RPM required to achieve the power required results in a very high piston ring swept area number. (for those who don't know, this is the single most important number with regard to BSFC). The little Honda might have to be at 4500RPM to achieve a "cruise" HP of 100. Where as a Lycoming 0-235 might be at 2300RPM. The Lyc also looses less combustion heat to the "cooling system" and therefore converts more "fuel to HP". The Lycoming also has only 8 valves and 6 cam lobes, The Honda, 16 valves and 16 cam lobes. The Lyc also is direct drive, no gearbox necessary, no gearbox losses or failures.
I really get on my soapbox with regard to this subject, but the "OLD" engineers that designed aircraft engines really knew what they were doing. It wasn't luck! BTW, my grandfather was one of those engineers! I still have many of his books, they are a real eye opener. There is so much lost knowledge, I don't even know where to begin. Not long ago, I forwarded the info one of his books on crankshafts to help solve a problem for a major manufacturer.
Chris
a typical new engine in a light, general aviation aircraft is really from a 1930's design and engineering mentality. They're huge displacement engines making low amounts of power. Compared to the amazing advances in automotive engines and turbine engines, the piston aircraft world has a long, long way to come to even reach 1970's technology.
the future may be with these diesel conversions.
Aviation piston engines achieve better BSFC numbers than many "Modern" engines, including diesels. 0.38 Lb/HP/Hr is a typical number for a modern Lycoming in cruise configuration. The Toyota Prius engine cannot achieve these numbers.
Low RPM, lower piston ring swept area numbers, large displacement and air cooling all contribute to excellent BSFC numbers. Couple the design advantages of "aircraft" engines with some modern technology such as electronic controls and efficiency numbers improve even more. It is not uncommon to see 200 to 320 cubic inch engines achieving more than 40 miles per gallon at speeds over 200MPH. Let's see your "modern" car do that!
To install an engine with "modern" technology would result in a loss of range, in most cases. Consider a typical Honda 4 valve, double overhead cam, high RPM engine as an example. The RPM required to achieve the power required results in a very high piston ring swept area number. (for those who don't know, this is the single most important number with regard to BSFC). The little Honda might have to be at 4500RPM to achieve a "cruise" HP of 100. Where as a Lycoming 0-235 might be at 2300RPM. The Lyc also looses less combustion heat to the "cooling system" and therefore converts more "fuel to HP". The Lycoming also has only 8 valves and 6 cam lobes, The Honda, 16 valves and 16 cam lobes. The Lyc also is direct drive, no gearbox necessary, no gearbox losses or failures.
I really get on my soapbox with regard to this subject, but the "OLD" engineers that designed aircraft engines really knew what they were doing. It wasn't luck! BTW, my grandfather was one of those engineers! I still have many of his books, they are a real eye opener. There is so much lost knowledge, I don't even know where to begin. Not long ago, I forwarded the info one of his books on crankshafts to help solve a problem for a major manufacturer.
Chris
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