of the stationary engine. There are at this time several manufacturers producing engines which will burn these fuels. Of course there are many other engines in which an attempt has been made by the use of various attachments to enable them to handle these fuels, but these are not oil engines in the strict sense of the word.

Practically nearly all the real oil burning engines operate on the two cycle principle and certain guarantees as regards fuel consumption are claimed by all the makers but it is especially noticeable that there are but few published tests giving any actual results obtained upon this type of engine. The writer recently had the privilege of making a test upon an 80-horse power engine of this type and the figures relative to the test are here gladly presented for the comment and reference of those interested.

crank case open and makes it easy to get at the bearings. Also the heat generated by the compression of the air does not affect the lubrication of the main bearings. It is also much easier to make the cylinder air-tight and prevent leaks than to enclose the engine bed. This style of construction, of course, results in a slightly longer engine.

A cross-sectional view of the engine is shown in figure 2. The bore of the cylinder was sixteen inches and the stroke of the piston twenty-four inches. The piston is shown at the inner end of the cylinder with the transfer and exhaust ports completely uncovered. The exhaust ports are opened considerably ahead of the transfer ports but they extend clear to the end of the stroke, giving an extremely large exhaust opening. The engine is of the three-port type, the intake port

being on the lower side of the cylinder. This style of engine consumes just a little more power due to the suction created in the pump chamber, but when it is considered that there are no valves whatever in operation, these ports being opened and closed automatically by the movement of the piston, this slight loss is more than offset. This type of engine is also quieter when running. The valve shown at the top of the cylinder is used only for priming the engine when starting. In starting, the ignition tube in the upper part of the cylinder head is removed and heated in a blast lamp to a dull red. This ignition tube is a piece of three-quarter inch pipe fastened to a steel head and held in the cylinder head by a quick acting clamp against a ground joint. The cylinder is primed with a little gasoline, and in the larger sizes compressed air is used for turning over the engine. Gasoline is also inserted through the priming valve at the front end of the cylinder, enabling the engine to run for a few

FIG. 2. LONGITUDINAL CROSS-SECTION OF PRIMM

ENGINE.

minutes in order to heat up the steel plate which is shown on the end of the piston.. The plate in the engine under consideration was five-sixteenths inch boiler iron, and eight inches square. After a few explosions this plate becomes sufficiently warm to vaporize the oil which is injected by the fuel pump through the spray nozzle in the center of the cylinder head. The governor is located on the crank shaft and controls the stroke of the fuel pump by moving an eccentric across the shaft, thus increasing or diminishing the eccentricity according to the speed. In many crude oil engines of this type the eccentric is slid directly across the shaft but in this engine the governor arm is attached to an eccentric pin which, as the governor flies out due to the increase in speed, not only moves the main eccentric towards the center of the crank shaft but also moves it ahead so as to maintain the point of injection practically constant at all speeds. The movements of the push rod driven by the main eccentric is, of course, greater than that of the plunger of the fuel pump, the latter being about three-eighths of an inch. As the movement of

indicator cards, combustion is practically the same at all loads, due to this advance of the main eccentric. The governor is not shown in the sectional view, it being on the forward side of the engine. In figure 1 the rod operating the fuel pump may be seen as well as the small lever which may be used for operating the fuel pump in starting, and which by its cam shape completely throws the plunger back out of contact with the push rod when the lever is pulled back. The small rod extending ahead from the fuel pump operates the water valve, which is the only manual adjustment on this engine, and after being once set requires no further attention. The valve itself is a small disc in which is drilled a number of small holes, which register with corresponding holes in the valve body; a slight movement of the pump plunger on light loads causes these holes to open only a slight amount, while on the heavier loads they will open a correspondingly greater amount. In the test here described no adjustment was made on the water valve during the test, it being set previously for The introduction of water into the heavy oil

a full load.

into the cylinder with the charge of air. The water vapor effectually keeps down the carbon deposits, and enables the engine to be run with a clean exhaust; it delays the ignition so that the fuel oil may be injected at an earlier position in the stroke, thereby transforming a greater number of heat units in the fuel into pressure on the piston.

In the test under consideration the oil used was a fuel oil of 321⁄2 degrees Baumé, weighing 7.2 pounds to the U. S. gallon. In the calculations the heating value of this oil was assumed as 18,000 B. t. u. per pound. The results of the test are given in the accompanying table, ten runs being made in order to obtain a sufficient number of tests from which curves might be plotted.

horse power was 18.4 per cent at 86.5-developed horse power. This figure is obtained by dividing 2,545 by the heat units in the oil used per developed horse power hour. The heat units are obtained by multiplying the pounds of fuel per developed horse power hour by 18,000.

In running tests of the oil engine, or, for that matter, any internal combustion engine operated on the throttling principle, it is extremely difficult to get indicator cards which represent the average conditions over any stated period. In this test about six indicator cards were taken near the beginning of each run, and about the same number near the end of the run. These cards were all measured and the average of all the runs taken as representing the conditions existing during that run. Indicator cards are

It will be noticed that the maximum developed horse power which was sustained was 94, or nearly 120 per cent of the horse power rating. These engines are very conservatively rated, and this is a feature which should be observed on all heavy oil engines.

The fuel consumption curve in figure 3 was plotted for both pounds and gallons per developed horse power hour. The particular feature to be noticed about this curve is that it is almost flat from 60- to 95-horse power, showing that between these points the fuel consumption remained practically at the minimum; this, in any engine, is a particularly valuable feature, and seems to be a characteristic of this engine.

The lowest fuel consumption per developed horse power hour was 0.107 U. S. gallon, or 0.77 pounds, which is at a cost of 0.53 cents per developed horse power hour. The total gallons of fuel per hour was also plotted, as well as the cost per ten hour day, with oil at five cents per gallon. At 80-developed horse power it will be noticed that the cost per day was about $4.40. However, the actual price of the fuel with which the engine was tested was 3.35 cents per gallon in carload lots, which would bring the above cost per day down to $2.95, which is a rather low figure for this amount of power, considering the cost of fuel as used in the average gasoline engine. It will be noticed that the fuel-per-hour-curve rises quite abruptly after reaching about 90horse power, showing the advisability of running the engine at or near its rated horse power. The highest thermal efficiency per developed

given at 30-, 60- and 94-horse power. The point especially to be noticed about these cards is that the conditions of ignition are practically constant, due, as before explained, to the operation of the governor. This governor maintains the load exceptionally steady and during the test the engine ran practically as well as a steam engine.

The indicator card from the pump end of the cylinder is also shown. In laying out the port openings on these cards it is found that atmospheric pressure is reached in the cylinder slightly before the piston closes the inlet port, showing that there is nò wire-drawing at this point. Atmospheric pressure is also reached before the piston reaches the transfer port. It is very essential in the two-cycle engine of this type to get as large a quantity of air as possible into the combustion chamber so as to insure driving out all the products of the previous explosion. That this condition is not entirely attained is acknowledged and great improvements are to be looked for in this type of engine along this line, but as the fuel consumption of this engine on the lower grades of fuel has reached that of the four-cycle engine, its position is assured. The mean effective pressure from the indicator cards for the various runs is given in line seven of the table while in line eight is given the mean effective pressure from which the indicated horse power was calculated. The mean effective pressure of the pump chamber has been subtracted from the total mean effective pressure of the cylinder, the compression of the charge of air not being considered