This paper discusses the combustion problems in various types of commercial vehicle engines.
Rate of pressure rise and peak pressure control the design of the engine structure and the amount of air which can be burned. These factors limit the design and use of hybrid engines.
Knock is discussed in relation to spark-ignition and compression-ignition engines on which new data are presented.
New data indicate that changes in fuel-air ratio and spark advance which lower spark plug and deposit temperatures increase exhaust valve temperatures. Ash deposits, spark plugs, and exhaust valves are most likely to trigger preignition.