Arizona republican., 1918-06-02
MODERN MAN|FOLDS RESPONSIBLE
 FOR EFFICIENCY |NAUTOMOB|LE

bowl of the carburetor, where it is passed through a very small opening. The partial vacuum that is created in the cylinders by the movement of the piston lifts the fuel into the combus- ton chamber. Now, if the fuel is very light and highly explosive, it flows into the combustion chamber without trouble. But when it is heavy, it does not flow readily, it's rate of flow de- creasing as it's weight increases. Ev- eryone knows that cold tends to thicken oil of any kind, gasoline as we'll as others. A fairly good grade of fuel may leave the carburetor pretty well volatilized but striking cold sur face, as the metal of an exposed mani fold, it will condense ..1l the walls and relatively little of it will reach the combustion chamber. This is the prob lem our engineers have endeavored to solve.
 Jacket Around Intake
 One of the first methods of improV- | ing the manifold was that of putting | jacket around the intake section at some position near the cylinders and passing either heated gases or hot Wa ter around the manifold. Another method was tried a little later Of bolt ing the carburetor directly to the cyl
 finder block. so that the heated gas l passage in the casing would supply | heat enough to vaporize the fuel. This 1 latter method is used to a great extent | now.
 | One school of designers tried the ex- | perment of heating the fuel before 1t reached the carburetor Still another group favored the idea of heating the | gasoline right in the carburetor Both l these methods had certain disadvan- | tages, from the fact that if fuel ts | heated before it gets to the carburetor | of even in that instrument, it still has
 an excellent chance of condensing again on it's way from the carburetor to the combustion chamber unless
 additional means of keeping it warmed is provided. If this latter is done, why l not perform the whole operation after
 the gasoline has left the carburetor. In a number of recent designs, the inlet and eXhause manifolds have been tplaced in close juXtaposition, with the intention of having the heated gases ! n the latter impart enough warmth
 10 the former to keep the fuel thor
 oughly vaporized. In similar designs
 the inlet manifold is made to pass
 through the exhaust outlet at single
 point. While these designs seem to
 give satisfaction, probably the most
 efficient method of handling the prob
 lem is found in the idea of incorporat-
 ing the inlet manifold within the cylin-
 der block, where it is practically sur
 rounded by hot volume and is close
 to parts that ordinarily run hot.
 Fitting of Air
 Another idea that contributes to ef-
 ficicnt carburetion is found in the fit ing of the air pipe leading to the T. 1.I. whereby after the engine is hot the shutter may be opened to admit cold air so as to obtain exactly the righi conditions for maximum of fuel ef- iiciency.
 Last year there was a violent ir- ruption of manifolds commonly called "hot spots" The name was accurately descriptive for it simply means a sp0 in the inlet manifold maintained at a high temperature, so that the gas in passing over it is warmed and made highly volatile. It is a peculiar fac that vaporized fuel does not take the same course as liquid fuel. Gas ol vaporiZed fuel, because of its higher kinetic values tends to travel in 6 straight line until it strikes some ob- struction, If this obstacle is part ol the inlet system, the liquid particles remaining in the fuel, will be vaporizeC without affecting the mixture by un- duly expanding it. Which brings us tC consideration of another phase of thu matter. But before we leave the "ho
 spot" let us point out that common idea that this feature belps in start ing the cold motor is totally erroneous 5 The hot spot does not get hot unti H the engine has run long enough t . become heated, so that the hot spo
 does not come into play until the en