The world of aviation engines often intersects with automotive technology, and the Austro Engine GmbH stands as a prime example. Born from a collaboration with Mercedes-Benz, Austro Engine has carved a niche in the aircraft industry by adapting and manufacturing engines initially designed for cars. This article delves into the story of Austro Engines, exploring their reliance on Mercedes-Benz technology, the engines they produce, and the ongoing discussions surrounding their design choices.
The Foundation: Mercedes-Benz OM640 Engine
The narrative of Austro Engines is intrinsically linked to the Mercedes-Benz OM640 diesel engine. When Diamond Aircraft, a prominent aircraft manufacturer, sought a reliable and modern engine for their aircraft, they turned to the automotive sector. The OM640, a four-cylinder diesel engine from Mercedes-Benz, became the foundation for Austro’s initial success.
Austro Engine, established with significant investment, strategically purchased a large stock of OM640 engines directly from Mercedes-Benz. These engines weren’t simply installed into aircraft; instead, Austro undertook a process of aviationizing them. This involved stripping off automotive-specific accessories and integrating essential aircraft components like gearboxes, Bosch ECUs (Engine Control Units), and other aviation-grade systems. The core of the Mercedes-Benz OM640 engine, including its robust cast iron block, remained largely untouched in this transformation.
Cast Iron vs. Aluminum: The Block Material Debate
One of the recurring discussions surrounding Austro Engines revolves around the material of the engine block – specifically, the choice of cast iron over aluminum. The original Mercedes-Benz OM640 engine utilized a cast iron block, known for its durability and robustness. However, modern automotive engine design often favors aluminum blocks for their lighter weight, contributing to improved fuel efficiency and overall vehicle performance.
The debate sparks from the question: why did Austro continue with the heavier cast iron block from the OM640, instead of potentially adopting a lighter aluminum alternative, especially as Mercedes-Benz themselves moved towards aluminum blocks in newer engine generations?
Several factors contribute to this decision:
- Certification Costs: Modifying the engine block material from cast iron to aluminum would necessitate significant re-certification processes for the engine itself and potentially for the aircraft utilizing it. Aviation certifications are rigorous and expensive, and sticking with the proven OM640 core minimized these costs.
- Aircraft Recertification: Diamond Aircraft, the primary user of Austro engines, would also face aircraft recertification if a lighter engine significantly altered the weight and balance characteristics. The existing airframe design was already adapted to accommodate the weight of the cast iron block engine.
- Historical Context: Thielert and Aluminum Blocks: Interestingly, a predecessor in the aviation diesel engine market, Thielert, initially used a 1.7-liter Mercedes engine with an aluminum block. When Mercedes superseded it with the 2.0-liter cast iron OM640, Thielert opted to develop their own aluminum block version to maintain compatibility and avoid airframe modifications for Diamond Aircraft. However, this expensive undertaking was cited as a contributing factor to Thielert’s eventual bankruptcy. This historical precedent likely influenced Austro’s conservative approach.
- Reliability and Overhaul: Cast iron blocks are often perceived as more durable and readily overhaulable compared to aluminum blocks, particularly in demanding applications. While aluminum blocks offer weight advantages, cast iron’s robustness might be favored for the longevity and reliability expected in aircraft engines.
Austro’s Current and Future Trajectory
As Austro Engines has matured and the initial stock of Mercedes-Benz OM640 engines dwindled, the company has adapted its strategy. Instead of relying solely on purchasing complete OM640 units, Austro has reportedly secured a license from Mercedes-Benz to manufacture the engine cores themselves. This move ensures a consistent supply chain and allows Austro to continue producing their AE300 and AE330 engines, which are based on the OM640 design.
This decision to manufacture the existing design, rather than significantly re-engineering it for an aluminum block or adopting newer Mercedes-Benz engine generations, underscores the priorities of certification stability and cost-effectiveness in the aviation industry. While newer Mercedes-Benz automotive diesel engines may feature aluminum blocks and advanced technologies, the proven reliability and established certification of the OM640-derived Austro engines remain a compelling proposition for aircraft manufacturers like Diamond.
Conclusion: A Calculated Path for Austro Engines
Austro Engine’s journey showcases a fascinating case study of automotive technology transfer to aviation. By leveraging the robust Mercedes-Benz OM640 engine, Austro has successfully developed a line of certified aircraft engines. While discussions around aluminum versus cast iron blocks and the adoption of newer technologies persist, Austro’s strategic decisions appear to be driven by a pragmatic balance of performance, reliability, certification costs, and market demands within the niche world of aviation diesel engines. For those in the automotive repair and Mercedes-Benz ecosystem, understanding Austro Engines provides a unique perspective on how automotive engineering principles are adapted and applied in the demanding realm of aircraft propulsion.
