Rotax Aircraft Engines, V
Rotax four stroke aircraft engines have proven themselves as reliable engines. They can be bought as experimental (UL) or certified (A and F) engine and there are three main models to date. The original engine is the 80 Hp 912, from which the 100 Hp 912S was developed and they also have a 115 Hp turbocharged 914 engine.
Recognizing the different models is easy: the 912 has black cylinder covers, the 912S green/blue (blue for the french market) and the 914 has red covers and a turbo. These are the most obvious differences.
As all engines, even the Rotax has its limitations in power, RPM, fuel and other temperatures. Keep in mind that we present this info without any warranty. The manuals from Rotax remain authorative.
Rotax Engine Operating Limitations
All Rotax four stroke engine have more or less the same limitations in RPM, temperatures and fuel requirements. Below a quick reference guide.
| Operating Limitations | |
| Take-off RPM (5 min) | 5800 |
| Max Continuous RPM | 5500 |
| Idle RPM | 1400 |
| 912 UL/A/F power at 5800 | 59,6 kW / 81 hp |
| 912 UL/A/F power at 5500 | 58 kW / 79 hp |
| 912 ULS/ULSFR/S power at 5800 | 73,5 kW / 100 hp |
| 912 ULS/ULSFR/S power at 5500 | 69 kW / 95 hp |
| 914 UL/F power at 5800 | 84,5 kW / 115 hp |
| 914 UL/F power at 5500 | 73,5 kW / 100 hp |
| Oil pressure | 7 bar max at engine start |
| Min Oil pressure | 0,8 bar below 3500 RPM |
| 1,5 bar below 3500 RPM (older models) | |
| Normal Oil pressure | 2 - 5 bar above 3500 RPM |
| 1,5 - 5 bar above 3500 RPM (older models) | |
| Max Oil Consumption | 0,06 L per hour |
| Max Oil Temperature ULS/S | 130°C (ULS/ULSFR/S) 140°C (UL/A/F) |
| Min Oil Temperature | 50°C |
| Normal Oil Temperature | 90 - 110°C |
| Max Cylinder Head Temperature | 135°C (ULS/ULSFR/S) (150°C UL/A/F) |
| Ideal CHT | 75 - 110°C |
| Fuel pressure | 0,15 - 0,4 bar |
| Hydraulic governor | 600 W |
| Vacuum pump | 300 W |
| Alternator | 1200 W |
Rotax Fuel requirements
The engine is built for lead free mogas, running it on AVGAS (100LL or 100) is possible but do take note of the limitations. Service Instructions SI-18-1997-R5 and SI-912-016-914-019 from Rotax explains it in more detail.
| Fuel Requirements | |
| 912 UL / A / F | 912 ULS / ULSFR / S |
| min. ROZ 90 | min. ROZ 95 |
| EN 228 Normal | ------------- |
| EN 228 Super | EN 228 Super |
| EN 228 Super Plus | EN 228 Super Plus |
| AVGAS 100LL | AVGAS 100LL |
