This table is based on data for the Lycoming O-320-D3G engine in the Piper Warrior II information manual, part no. 761 780, but it may be roughly applicable to other 160 hp engines hooked up to a fixed-pitch, cruise propeller. I have extrapolated the data below 0 ft density altitude to allow for winter flying.
DO NOT USE THIS TABLE FOR FLIGHT PLANNING!
It may contain mistakes and definitely contains extrapolated data. Use your POH and/or an official engine manual from the manufacturer.
The numbers in the body of the table show the percentage of rated brake horsepower produced by the engine; for example, at 6000 feet density altitude and 2400 rpm, the engine will produce 60% of its rated power, or 96 bhp. The green area represents the ideal range for running the engine, between 55% and 75% power. The red area represents a power range that is too high for cruise (possibly resulting in detonation and engine damage), while the yellow area represents power settings lower than normally used (resulting in very slow airspeeds); again, use your POH for confirmation.
| Density Altitude | ||||||||||||||||||
| -2000 | -1000 | 0 | 1000 | 2000 | 3000 | 4000 | 5000 | 6000 | 7000 | 8000 | 9000 | 10000 | 11000 | 12000 | 13000 | 14000 | ||
| RPM | 2000 | 44 | 43 | 41 | 40 | 38 | 37 | 35 | 33 | 32 | 30 | 29 | 27 | 26 | 24 | 22 | 21 | 19 |
| 2050 | 48 | 46 | 45 | 43 | 42 | 40 | 39 | 37 | 35 | 34 | 32 | 31 | 29 | 27 | 26 | 24 | 23 | |
| 2100 | 51 | 50 | 48 | 47 | 45 | 44 | 42 | 40 | 39 | 37 | 36 | 34 | 33 | 31 | 29 | 28 | 26 | |
| 2150 | 55 | 53 | 52 | 50 | 49 | 47 | 46 | 44 | 42 | 41 | 39 | 38 | 36 | 34 | 33 | 31 | 30 | |
| 2200 | 59 | 57 | 55 | 54 | 52 | 51 | 49 | 47 | 46 | 44 | 43 | 41 | 40 | 38 | 36 | 35 | 33 | |
| 2250 | 62 | 60 | 59 | 57 | 56 | 54 | 53 | 51 | 49 | 48 | 46 | 45 | 43 | 41 | 40 | 38 | 37 | |
| 2300 | 66 | 64 | 62 | 61 | 59 | 58 | 56 | 54 | 53 | 51 | 50 | 48 | 47 | 45 | 43 | 42 | 40 | |
| 2350 | 69 | 67 | 66 | 64 | 63 | 61 | 60 | 58 | 56 | 55 | 53 | 52 | 50 | 49 | 47 | 45 | 44 | |
| 2400 | 73 | 71 | 69 | 68 | 66 | 65 | 63 | 61 | 60 | 58 | 57 | 55 | 54 | 52 | 50 | 49 | 47 | |
| 2450 | 76 | 74 | 73 | 71 | 70 | 68 | 67 | 65 | 63 | 62 | 60 | 59 | 57 | 56 | 54 | 52 | 51 | |
| 2500 | 80 | 78 | 76 | 75 | 73 | 72 | 70 | 69 | 67 | 65 | 64 | 62 | 61 | 59 | 57 | 56 | 54 | |
| 2550 | 83 | 81 | 80 | 78 | 77 | 75 | 74 | 72 | 70 | 69 | 67 | 66 | 64 | 63 | 61 | 59 | 58 | |
| 2600 | 87 | 85 | 83 | 82 | 80 | 79 | 77 | 76 | 74 | 72 | 71 | 69 | 68 | 66 | 64 | 63 | 61 | |
| 2650 | 90 | 89 | 87 | 85 | 84 | 82 | 81 | 79 | 77 | 76 | 74 | 73 | 71 | 70 | 68 | 66 | 65 | |