Abstract
The type of test which a carburetor is most frequently given to establish its merit or lack of merit is carried out in the following manner: An engine in good mechanical condition is tested, using a carburetor which bears a high reputation. These tests are then repeated, using the new carburetor, and its merits are thus reported in terms of the comparative performances of the engine. The results of these tests are valuable and convincing, and while they will always be the final criterion of carburetor performance, they fall a little short of the ideal in that they fail to show the reasons for the differences. Several writers have recently pointed this out and suggested that the performance of a carburetor should also be expressed in terms of its ability to perform those functions which are essential to proper carburation. In order to do this it will be necessary to determine these essentials. Each function must then be studied to see when and how it operates, its comparative importance, and the conditions for the best results. This is a difficult task, but its accomplishment should prove of great benefit. In this paper a list of the essential factors, as now understood, has accordingly been made. Some experimental data are also presented which it is hoped will help to establish some of the standards of performance. These data cover the following points:
(a) The efficiency and power capacity of an engine as affected by the richness of the mixture
(b) The effect of the speed of an engine upon its mixture requirements
(c) The effect of the torque produced by the engine upon its mixture requirements
(d) The effect of the dryness of the mixture upon the mixture requirements, power and efficiency of the engine:
1 The heat for drying the mixture coming from the sensible heat in the air
2 The heat for drying the mixture coming from a “hot spot” in the intake manifold.
Further research is now under way which is expected to throw light on other phases of the problem.
