The Rotax 912iS offers several advantages over the 912ULS, mainly due to its fuel injection system. Here’s a breakdown of the key differences:
1. Fuel Efficiency:
- 912iS: Equipped with a fuel injection system, the 912iS is significantly more fuel-efficient compared to the carbureted 912ULS. The fuel injection system optimizes fuel usage depending on flight conditions, which can result in up to 30% better fuel economy in some flight regimes.
- 912ULS: Uses a dual carburetor system, which, while reliable, is generally less fuel-efficient, especially at varying altitudes and engine loads.
2. Altitude Compensation:
- 912iS: The fuel injection system automatically compensates for changes in altitude and atmospheric conditions, ensuring consistent power delivery and fuel efficiency at higher altitudes.
- 912ULS: Requires manual adjustments with the carburetor for altitude changes, and its performance may degrade without these adjustments.
3. Ease of Operation and Maintenance:
- 912iS: The fuel injection system reduces the need for carburetor maintenance (like syncing dual carburetors), which can simplify long-term maintenance. The engine is also equipped with an electronic engine management system, making it more adaptable to modern avionics and flight monitoring systems.
- 912ULS: While the carburetor is straightforward and reliable, it does require regular maintenance and tuning to ensure optimal performance, especially if flying in varied environments.
4. Power Consistency:
- 912iS: The electronic fuel injection system provides more consistent power delivery, particularly in varying flight conditions, ensuring smoother and more predictable engine performance.
- 912ULS: Can experience slight variations in power delivery depending on carburetor settings and altitude.
5. Emissions and Environmental Impact:
- 912iS: The fuel injection system provides a cleaner burn, leading to lower emissions and a reduced environmental footprint. This makes the engine more compliant with modern environmental standards.
- 912ULS: Has slightly higher emissions due to the carbureted system, especially when not optimally tuned.
6. Technology Integration:
- 912iS: The engine management system allows for better integration with modern avionics, flight computers, and diagnostic systems, enabling real-time monitoring of fuel consumption and engine health.
- 912ULS: Lacks this advanced electronic integration, relying on traditional methods for engine performance monitoring.
Downsides of the 912iS:
- The 912iS is heavier than the 912ULS and more expensive upfront.
- Maintenance of fuel injection systems can be more technical, requiring specialized knowledge.
In summary, the 912iS offers better fuel efficiency, easier maintenance, and more consistent performance, particularly at higher altitudes, but at a higher cost and slightly increased complexity.