Converting a 180HP 172S to a 160HP?

[CFI A&P]

The 160HP burns 7.9 per hour. The 180 burns 12/hr. If your plane flies 80 hours a month thats roughly $20k per year in savings.

That math doesn't add up. There is a relationship between hp and fuel consumption and in this case (naturally aspirated) you're increasing about 12% in hp but claiming fuel consumption is up 50%.

By the way, the only time I've seen 12gph out of a 360ci Lycoming was in an aerobatic application.

 

[mrivc211]

That math doesn't add up. There is a relationship between hp and fuel consumption and in this case (naturally aspirated) you're increasing about 12% in hp but claiming fuel consumption is up 50%.

By the way, the only time I've seen 12gph out of a 360ci Lycoming was in an aerobatic application.

I was going based on our SP’s fuel flow indicator always being between 10-15gph. I read a lot of contrary statements on here so I went back to the POH and it stated more like 10gph. That’s a lot better.

 

[CFI A&P]

I was going based on our SP’s fuel flow indicator always being between 10-15gph. I read a lot of contrary statements on here so I went back to the POH and it stated more like 10gph. That’s a lot better.

A rough rule of thumb is 10% of hp is WOT fuel consumption - 180hp = 18gph. 5% of of hp is cruise fuel consumption - 180hp = 9gph.