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PREIGNITION is defined by Mr. Winch as the initiation of a flame front by some means other than the spark discharge at some point in the combustion chamber prior to the arrival of the normal flameat that point. He believes that wild ping is actually a combination of preignition and knock. His study of both 1952 and 1953 cars indicates that preignition has become a very serious problem. Moreover, in some cases, the problem was found to be more serious in the 1953 car of a particular make than in the 1952 model. In these studies preignition and wild ping were identified by a technique that makes use of the spark plug as an ionization gap.

ENDURANCE limits and load losses at various temperatures from -75 F to 650 F for several spring materials are reported in this paper. The materials tested were in the form of helical springs, both shot peened and unpeened. Some general observations made by the authors include: 1. Shot-peened springs had higher endurance limits and greater relaxation than unpeened springs at -75 F and 75 F. 2. As test temperatures rose above atmospheric, endurance limit of all unpeened springs tended to hold steady or increase somewhat, while that of shot-peened springs tended to decrease. 3. Except for high-speed steel and stainless steel, chrome-silicon steel showed lowest load loss in both static and dynamic tests in the temperature range from atmospheric to 450 F. 4. Both unpeened and shot-peened high-speed-steel springs showed high endurance limits at all test temperatures. 5. Endurance limits at -75 F were similar to those at atmospheric temperature, but the amount of set was less, on the average.

SEVERAL 2-stroke-cycle diesel engines of European manufacture are described in this paper. The 2-stroke-cycle diesel was late to appear in the automotive scene in Europe, but noteworthy developments have taken place recently, according to the authors. In England, a couple of successful uniflow engines were placed on the market, while on the Continent the loop-scavenged engine is receiving most of the attention. The authors feel that this is not a step backward dictated by European poverty, but perhaps a step forward toward compactness and simplicity.

RESULTS of an investigation into the effect of shot-peening variables and the resulting residual stresses on fatigue life are reported in this paper. Leaf springs were the simple specimens heat-treated, cold worked, and tested in this study. Some of the conclusions reached are: 1. There is a minimum shot velocity for each shot size to obtain best fatigue life, and this value is much lower than that normally used. 2. Exposure time for this type of shot-peened specimen beyond some minimum value is wasteful and costly. 3. Shot size has little influence on fatigue life for these specimens. 4. Shot peening specimens while under tensile strain greatly increases fatigue life at 200,000 psi nominal stress over that of nonpeened or strain-free-peened specimens. 5. Shot peening these specimens gave residual compressive stresses 50% of yield strength, and these stresses can be increased to more than 50% by strain peening. 6.

THE design and construction of the PowerFlite automatic transmission are described by the authors. It is of the torque converter type, some models being water-cooled, while others are direct air cooled. Details of the hydraulic controls are explained, including the one-piece shift valve and the shuttle valve for controlling closed-throttle shifts. It is claimed that this transmission has relative simplicity, light weight, and smoothness of operation.

THIS paper presents flame temperature and pressure data taken on a spark-ignited CFR engine. Data are presented for the four variables of cyclic reproducibility, knock, air/fuel ratio, and ignition timing. The data indicate that cycle-to-cycle irreproducibility may be caused by variations in the initial rate of flame propagation from the spark.

THIS paper discusses a method of measuring compression temperature by means of the absorption of light. An optical-electronic system measures the change in color of a trace of iodine gas that has been added to the intake mixture. From these measurements the temperature of the iodine and by inference, the temperature of the gases, is determined. The apparatus used is described briefly and the test results obtained in measuring compression and end-gas temperatures in a spark-ignition engine are also presented.

THE indicated output of a 2-stroke engine is primarily dependent upon the success with which the products of combustion are driven from the cylinder and are replaced by fresh air or mixture during the scavenging period. Such replacement must, of course, be accomplished with a minimum of blower power. This paper deals with various aspects of 2-stroke research conducted at M.I.T. during the past 10 years. Among the subjects discussed are the methods used in the prediction and measurement of scavenging efficiency, and the effect of engine design and operating variables on the scavenging blower requirements as reflected by the scavenging ratio.