F/A by EGT (Mixture Control by Exhaust Gas Temperature)

After more than thirty years of effort to obtain a simple and accurate fuel-air ratio indicator for mixture control of piston engines, it was recently discovered that mixture ratios can be simply, accurately, and consistently defined by the use of an exhaust gas temperature indicator of high sensitivity and very fast response. The first mixture indicator using EGT was placed on the market in 1962, and there have been five such indicators advertised to date. There are presently over 10,000 aircraft engines that have their diets controlled with the ALCOR Mixture Control Indicator. The development of the EGT method of mixture control is described and design requirements are presented and explained. Data are presented on the effect of fuel-air ratio on exhaust gas temperature, cylinder head temperature, horsepower and brake specific fuel consumption. Effect of engine variables is descussed and data presented. The use of an EGT indicator as an engine analyzer for trouble detection is discussed and data presented. The question of “How lean is too lean?” is discussed.