Texas Compressed Natural Gas (CNG) Delivery Truck Driver Practice Exam

CNG vehicles are less susceptible to engine knock primarily because CNG has a higher octane rating than gasoline. The octane rating is a measure of a fuel's ability to withstand compression without igniting prematurely. Higher octane fuels can survive greater compression in the engine cylinders before combusting, which is crucial for preventing engine knock—an undesirable condition that can damage the engine. In the context of a CNG vehicle, the higher octane rating allows for more efficient and higher compression ratios during combustion, leading to improved performance and reduced knocking. Due to this property, CNG can be run in engines designed for higher performance without the same risks associated with lower octane fuels like gasoline. This means CNG provides a smoother and more controlled burn, contributing to better engine health and efficiency.