As the advancement of metal additive manufacturing (AM) technology persists, so will the expansion of its capabilities and applications. In particular, the automotive industry can benefit from the advantages provided by AM, such as flexibility in design and customized products. In this avenue, one potential application of AM is in internal combustion engines (ICEs). As a first step, this effort explores the feasibility of using AM to produce working ICE components for an air-cooled engine. The cylinder head and crankcase of an 11 cm3 displacement volume Saito FG-11 engine were the components identified for metal AM. They were manufactured through Laser Powder Bed Fusion (LBPF) and post machined to achieve the necessary tolerances. Engine testing encompassed both propeller and dynamometer setups with corresponding data collection to measure and compare engine performance. Each engine was monitored at the same specific set points during operation for speed, torque, temperatures, pressures, airflow, and mass flow rate of fuel. The results show that the performance parameters of the AM engine were marginally degraded with produced torques of 0.05-0.10 N⋅m (7-14%) lower for dynamometer testing, and wide-open throttle engine speeds that were 500-700 rpm (6-13%) slower during propeller testing. Despite these diminished outputs, the AM engine was operable and ran without failure or damage for over 3.5 hours during testing. The major influencers behind the reduced performance were hypothesized to be either variations in assembly or increased friction from an insufficient hypereutectic honing procedure. Overall, the AM process was not considered a cause of the diminished output, thus highlighting the potential of AM for major ICE parts.