Page 12 Advertisements Column 1

Sun (Auckland), Volume II, Issue 603, 4 March 1929, Page 12

A MESSAGE OF VITAL INTEREST TO MOTORISTS appotenic (: ap po-ten" ik ) %% The quality in a motor spirit that ensures perfect Combustion ! In previous announcements the reasons for adding this word “appotenic” to the motorist’s vocabulary have been outlined. Merc, we discuss the question of Combustion. A.s a motor owner, the knowledge of how ideal combustion is attained will prove of vital interest to you. 1 1 * * appotenic \_frc: : Latin: ad (ap), meaning added to; and potens, meaning powerful ] possessing increased power; said of a gas that, being stable to heat and high compression will therefore neither audibly nor silently “knock” in a high compression engine. A".L JS This diagram shouts correct combustion—with ‘Plume the appotenic motor spirit This diagram shoivs incorrect combustion—with motor spirit unstable to heat and high compression Plume, defying high temperatures, powerfully resisting the disrupting influences of high compressions, burns evenly and steadily. The expansion of the gas following this correctly-timed combustion delivers a powerful, thrusting push to the piston. It maintains this steady surge of power throughout the length of the power stroke, enabling your engine to deliver its full horsepower. Correct combustion follows naturally when appotenic motor spirit is used. Plume will deliver maximum power without silent or audible “knock,” despite the stress of hill climbing in top gear or the heavy-load strain of low gear “plugging” through sand or mud. When you use a motor spirit that is unstable under heat and high compression, a chemical change takes place in the charge shortly after the instant of ignition. The temperature and pressure of the ignited portion “A” raises the temperature and pressure in the remainder of the charge to suc h an extent that it spontaneously ignites, or “goes off,” in uncontrolled combustion. Flames rip through the charge, hitting cylinder walls and piston, resulting in what is commonly called a knock. hether this “knock 7 ’ is silent or audible, the propulsive power of the charge is wasted in violent, spasmodic expansion, which the piston cannot absorb. Retarding the spark, or cutting down to second, may cut out the sound of the knock, but it is simply a case of shutting the stable door after the horse-power’s gone. The quality of crudes differs widely. Some crudes produce motor spirits unstable to heat and compression. These will spontaneously ignite at lower temperatures than Plume—the motor spirit distilled from the appotenic crude. Plume—appotenic, heatresistant —will withstand temperatures in a combustion chamber which would cause inferior motor spirits to “knock” either audibly or silently. Our next announcement will explain the significance of the “silent knock.” Safeguard yourself ! Fill up at the Plume pump ! VACUUM OIL COMPANY PTY. ltd. "IKe J2 s WLMt V: spA 7 9* // ' / No. 3 of a Series.