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Carbureted vs Fuel Injected

by Myron Yoder

feature_maint_1In carbureted engines, the fuel/air mixture meets in the carburetor. The mixture then goes to each cylinder through the air intakes. In the fuel injected engine, the fuel and air do not mix until they reach the cylinder. Since fuel injection systems shoot fuel directly into the cylinders, they are easier to flood (too much fuel) when starting. For this reason, starting procedures for fuel injected engines vary a good bit depending on the aircraft/engine combination. Carbureted engines undoubtedly take less talent to get started.

Though they are easier to start, carbureted engines are less efficient during flight. Since the fuel/air mixture in carbureted systems meet at the carburetor, the mixture is less precise for each cylinder. Fuel injectors are calibrated to force the same amount of fuel into each cylinder. Because of their precision, most fuel injection systems also permit monitoring of each cylinder’s EGT (Exhaust Gas Temperature). EGT probes on each cylinder allow the pilot to create the ideal engine performance; saving fuel, as well as reducing wear on the engine. For these reasons, as well as many others, fuel injected engines are standard on most new aircraft.

Carbureted systems are simple: less parts, less complexity, less maintenance. In fact, our carbureted Cessnas do not need fuel pumps since the fuel tanks are high (in the wings) and push the fuel all the way to the carburetor. One thing carbureted engines do need is carb heat. When activated, carb heat allows air to flow around the exhaust (to heat up) and then into the carburetor — bypassing the induction filter. The hot air melts/prevents ice buildup around the throttle valve. Fuel injected engines do not need carb heat, but they do need electric fuel pumps as a starting flow, as well as a backup for the engine-driven fuel pump.

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