A Study of Cylinder-to-Cylinder Distribution of Charge in a Six Cylinder Spark Ignition Engine

An experimental and theoretical study of inlet flow was carried out on a Ford V6 Zephyr four-stroke cycle spark ignition engine. Details of measurements of individual cylinder flows were made on one bank of three cylinders (Nos. 4, 5, and 6) over a range of engine speeds from 1500 to 3500 rpm and throttle positions, full (WOT) down to 1/4 position. The object of the investigation was, first, to determine experimentally the extent of the variation of flow rate from cylinder to cylinder with changes in throttle position and engine speed and, secondly, to determine whether the computer simulation could confirm the trend. The main results of the tests showed that the outer two cylinders, No. 4 and No. 6, had the same flow rate within a variation of about 1/2 percent and that the middle cylinder, No. 5, had about 3 percent more flow at low speeds and 1 percent more at high speeds. In the main these were confirmed by the computer calculations. The volumetric efficiencies were also determined; these produced fairly smooth curves decreasing about 4 to 6 percentage points over the speed range and decreasing progressively as the throttle was reduced. There was evidence of recovery in the magnitude of volumetric efficiency at higher speeds and smaller throttle openings. The computer results also produced these trends.