How does altitude affect the performance of a naturally aspirated internal combustion engine used in a generator set?

Altitude significantly affects the performance of a naturally aspirated internal combustion engine used in a generator set because air density decreases with increasing altitude. A naturally aspirated engine relies on atmospheric pressure to force air into the cylinders during the intake stroke. As altitude increases, the air becomes less dense, meaning there are fewer oxygen molecules per unit volume. This reduced oxygen density results in a lower mass of air entering the cylinders, leading to incomplete combustion ....