Report discussing testing on two types of single cylinders to determine the effect of the relation of exhaust pressure to inlet-air pressure on knock-limited performance. Variables explored included exhaust pressure, fuel-air ratio, and engine speed. Three types of fuels were also used to explore the effect of exhaust pressure on fuel ratings.

"A critical review of literature bearing on the autoignition and detonation-wave theories of spark-ignition engine knock and on the nature of gas vibrations associated with combustion and knock results in the conclusion that neither the autoignition theory nor the detonation-wave theory is an adequate explanation of spark-ignition engine knock. A knock theory is proposed, combining the autoignition and detonation-wave theories, which introduces the idea that the detonation wave develops in autoignited or after-burning gases, and ascribes comparatively low-pitched heavy knocks to autoignition but high-pitched pinging knocks to detonation waves with the possibility of combinations of the two types of knocks" (p. 317).