I have a question about the chart the previous post linked to. I have 2 aircraft same make and both with pretty much the same airframes. One has a FP and a o-360-C1F engine and the other has a CSP and a 0-360 C4F, if I'm reading the chart correctly the C4F burns 1.2 GPh less running at the same 65% of power, can the CSP really make that much of a saving ?