The Effects of Operating Conditions of the Engine on Antiknock Properties of Gasolines (3)

Abstract

Antiknock qualities of clear catalytically reformed naphtha and with tetraethyl lead (TEL) and tetramethyl lead (TML) were studied under various operating conditions of the CFR engine. The operating variables investigated were engine speeds of 600, 900 and 1, 200rpm, ignition timing of 5° to 35° BTDC, air-fuel ratio between 10 and 16, and inlet mixture temperatatures of 50° to 150°C. The lead response was evaluated from increase of incipient knock limited compression ratio.The effect of TEL or TML varied with engine operating conditions, but generally, lead response in catalytically reformed naphtha was greater at richer mixture and at retarded timing of ignition.Because the relative effectiveness of TML to TEL varied considerably, depending on operating conditions and lead concentrations, it was difficult to state absolutely which was more effective than the other. It was found that the relationship between the incipient knock limited compression ratio and lead concentration was expressed by the same type of empirical equation as found on octane number and lead concentration.