Studies on the Application for Farm Tractor Drive of LP Gas (II)

Comparison of the Engine Performance under Different Venturi Diameter

Abstract

In this report, the engine performance were compared by five different diameter of carburetter venturi which are used both for LP Gas fuel and gasoline fuel. Following results were obtained.
(1) At the maximum output, the performance of 20mm diameter venturi was higher than the others on gasoline and LP Gas fuel. Generally, small diameter venturi were not good. The LP Gas fuel and large diameter of venturi were good in the limit of maximum output, and effective range was 6-10PS.
(2) According to the three dimentional curve (solid curve) among output, fuel consumption and venturi diameter, there was no correlation between gasoline and LP Gas fuel, but 22mm and 24mm dia. venturis were good.
(3) On the costs of fuel consumption, 20mm dia. venturi was the cheapest, and large diameter ones were suitable for both fuel. The cost of gasoline was higher than LP Gas fuel by 10yen/PS-hr at the minimum cost of fuel consumption.
(4) On the relation between supreme adequate outputs and costs of fuel consumption on solid curve, the performance was good when the curve has no snake type properties. Therefore the large diameters were surpassing.
(5) On the mixture ratio of fuel and excess air ratio, gasoline was better than LP Gas fuel. Generally, the mixture ratio was high at low output in the case of gasoline and at high output in the case of LP Gas. On all output condition, we wished that gasoline might be used by half load, but LP Gas might be enlarged the all range.
As the result of this report, we found 22mm of venturi diameter was best through every experiments, and LP Gas venturi throat had to be 10% smaller than the air inlet pipe of gasoline engine.