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Show EFFICIENCY SUM W VME-llf',0 TYPE Location Allows Hot Gases to Escape Quickly and Without Difficulty. How complex is Die problem confronting confront-ing the automobile designer in building the modern car can be better appreciated "when it is known that economy of operation oper-ation is very largely dependent on such nn apparently insignificant point as the location or" the valves in the ryliiKltrs. The location of valves determines the shape of the combustion chamber, an important factor in efildent operation in view of the part it plays in determininK the rate of combustion, the heat !o through the cylinder walla, the thoroughness thorough-ness with which the cylinder is cleared of burned Rases and the- amount of fuel condensation. Engineers discovered back in the early days of the internal combustion engine that the greatest power could be obtained ob-tained from a given amount of fuel in a Epherlcal combustion chamber. Compared with this ideal, which cannot be attained because of mechanical limitations, three types of cylinders are commonly made use of: L-head, T-head and valve-in-the head. The latter most closely approaches ap-proaches the ideal, as it preserves the interior in true cylindrical form. On the other hand, the ir regular i ties in the Bhape- of the interior, which are characteristic char-acteristic of the I-head and T-head types the valve- pockets are like alcoves to a room Increase the internal surface exposed to the heat of combustion, thus decreasing thermal efficiency; they trap the exhaust gases, which dilute the fresh charge, thereby reducing the power; they retard combustion, as the spark is not located in the center of the chamber and ignition must travel farther to reach the most remote parts of the fuel charge; and they allow condensation of the heavy parts of the fuel, as the valve pockets are cooler than the cylinder proper. The trade papers and automobile sections sec-tions of newspapers have commented a good deal recently on the fact that there are more cars with valve-ln-the-head engines en-gines on exhibition at shows this year than ever before. "Engineers say that 25-cent 25-cent gasoline is forcing the adoption of the most economical type of engine that can be built. The Franklin has always been a leading lead-ing exponent of scientific design and efficiency ef-ficiency in motor car construction, and the tie of the valve-ln-the-head type of cylinder in the Franklin en.slne has been standard practice since 1JK2. Incidentally, the Franklin was the first car in the American field with a valve-ln-the-head engine. |