Canuck
David Megginson
- Joined
- Mar 31, 2016
- Messages
- 7,077
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Since we've been talking a lot about leaning, CHTs, etc., I decided to share a scan of the chart from the Lycoming (I)O-320 Operator's Manual (PN 60297-16) illustrating the effect leaning on CHT, EGT, and power. This curve looks the same for all piston engines, but it's nice to have one specifically for the engine in the smaller Cherokees.
The chart can take a while to figure out, but the main point is that the standard advice (lean to peak EGT then enrich 50°F), according to Lycoming's own chart, causes the hottest CHTs possible. Max power (highest RPM) happens around 100°F on the rich side of peak EGT, at which point CHTs are already starting to drop noticeably.
View attachment 320-power-curve.pdf
The chart can take a while to figure out, but the main point is that the standard advice (lean to peak EGT then enrich 50°F), according to Lycoming's own chart, causes the hottest CHTs possible. Max power (highest RPM) happens around 100°F on the rich side of peak EGT, at which point CHTs are already starting to drop noticeably.
View attachment 320-power-curve.pdf
