The Bridgeport times and evening farmer., 1919-07-29
Interesting Facts On
 Ignition We'll Worth
 Attention Of MOtOriSt
CLEAR UP KNOTTY POINTS MUCH DIS- PUTED-TIN1ES READERS AT LIBERTY
 TO ASK QUESTIONS.
Ignition Facts Worth Knowing.

interested in the subject of ignition,
 and the following two letters un-
 doubtedly make clear many facts not
 generally known:
 To the Editor:
 Many articles have been publish
 ed recently stating that magneto ig-
 hilton Is better than battery system | Ignition. n
 You know 1t is quite commonly stat
 cd that the intensity or heat of the spark effects the completeness or ! quality of combustion, consequently
 of the power and economy of the
 motor. As I see 1t, the burning of fuel
 in the cylinders is something like l this:
 The spark occurs between the el-
 ectrodes and this spark heats the in
 tervening and adjacent gas to such ! degree that its kindling point is | reached and combustion begins. The amount of gas so heated by | the passage of the spark Is infinitesi- l nal; combustion having thus been l started continues by what is called i flame propagation, that is to say, the | contact of the hot burning gas with | adjacent unburned gas. The rate of i flame propagation, also the character ! and completeness of combustion. de- ! bends upon the temperature, density
 
 | upon little else, If anything. l The spark cannot affect any gas | which it does not directly heat, conse- | quently it cannot affect the rapidity or completeness of combustion of any portion of the mixture except that | which it actually heats between the l electrodes.
 i If the foregoing propositions are correct, it follows that with a given ] moi tor nd R1 ivt
 tions, and spark timing, the intensity | of heat of the spark cannot have 1 anything to do with the efficiency
 or power of the motor. If, on the | other hand, it is insisted that the in | tensity of the spark does have some | thing to do with the efficiency and | power of the motor, it will be neces- | sary to establish a compressed hydro | carbon mixtures and that the parti- | cular type of combustion which is l started and propa gated throughout | the combustion chamber can be and ! is controlled by the character of the | spark which initiates combustion. Now please do not think that I am i advancing the hypothesis of different | types of combustion. I am in fact ! very skeptical as to whether any such | thing occurs. mention it only as the necessary basis for any proposition | that the heat of the spark can have | anything to do with the efficiency | and economy of the motor. | Although I am strong for magneto | ignition myself, I shall be glad If you will send me explanation which 1 makes the facts in the case square | claims.
 Thanking you for your attention, l am,
 1 CSigned) w B. JONES' | Dear Sir:
 | Replying to your letter: | You remark that: "It is quite com | monly stated that the intensity of the | heat of the spark affects the quality 1 of combustion. consequently the pow { CT and economy of the moto.." l You question this being so. Your entire question is well expressed, and | covers a wide field, but is based on 1 wrong argument and hypothesis. l You elaborate further, in detail, up- | on the basic theory that the amount of gas heated by any kind of a spark | is infinitesimal and combustion hay | ing started, continues, as if one fuel | molecule must be well-burned, or ig- nited, before the next fuel molecule catches fire.
 Scientifically this might be true, and if oscnIographs are taken at the rate of several thousand a second, it might be proved that a big fat, mag neto spark ignites at once and scat ters, by its intense spark, which in it. self is a very powerful miniature ex- plosion, molecules crowded together under compression, and like a handful of pebbles thrown into a pond, each makes its own circle; in this case they are molecule conclusions, which ig- mite all the fuel faster than any weak spark could.
 It is well-known fact that with a magneto spark of a given neat-vatue of from 300 to 1000 degrees C., 1t is possible to burn leaner mixtures with a. considerably shorter timing range, and carrying a better power curve for like motor speeds.
 These elements have to be consid- cred in making clear the fact that the intensi y and heat of the spark do considerably, and favorably, affect the quality of combustion, and con- sequently do increase the efficiency and power of the engine. This in no way establishes different types or or dors of combustion of compressed hydrocarbon mixtures, but does, in | my opinion, mean that as a hydrocar- | bon mixtures burn slowly, power is derived by the conversion of heat ener- | gy into mechanical energy through | the medium of expansion of the heat | ed gases to q lower temperature, and l by the speed of impulse.
 Total combustion is necessary to get the full power containing in the fuel. :! The duration of the magneto spark Is two or three times longer than that of the battery spark. as shown by os- cfllographS of an official test repre- senting the highest development or the battery system. as used on the Liberty Airplane Motor, operated at eight volts. Commercial battery sys- toms as applied to passenger cars op- crate on six volts.
 If dozen intense magneto sparks were used the same compression, quantity and quality of mixture, would undoubtedly give more power because of quicker combustion expansion and consequent greater impulse,
 The combustible mixture on the compression cycle in the combustion engine is constantly changing its pos ition in relation to the spark plug |