* Weight: Small-block Chevy engines are relatively heavy compared to purpose-built aircraft engines. Aircraft design prioritizes lightweight components for efficiency and performance. The added weight would significantly impact the airplane's fuel efficiency and performance.
* Reliability: While durable for automotive applications, a small-block Chevy wasn't designed for the constant vibration and stress of sustained flight. Reliability in the air is paramount, and a failure at altitude is catastrophic. Aircraft engines undergo rigorous testing and certification to ensure they can withstand these conditions; a modified car engine doesn't have this.
* Certification: Getting a homebuilt aircraft certified (even an experimental one) with a non-certified engine is incredibly difficult, if not impossible. The FAA has specific requirements for aircraft engines, and a repurposed Chevy engine wouldn't meet those requirements.
* Cooling: Aircraft engines require specific cooling systems designed for the altitude and airspeed. Adapting a car engine's cooling system for aviation use is complex and may not be effective, leading to overheating.
* Fuel system: Aircraft fuel systems are designed for safety and reliability at altitude. Adapting a car fuel system presents significant challenges and safety risks.
* Propeller compatibility: Matching the engine to a suitable propeller is critical for performance and safety. Finding a propeller compatible with a modified small-block Chevy would require specialized knowledge and custom fabrication.
* Maintenance: Maintaining an aircraft engine requires specialized knowledge and tools. Maintaining a modified car engine in an aircraft context adds considerable complexity.
In short, while technically feasible with extensive modification, using a Chevy small-block for a homebuilt airplane is highly impractical, unsafe, and likely to lead to a significant increase in complexity and cost without any compensating benefits. Purpose-built aircraft engines are designed specifically for aviation requirements and are the only sensible choice.
