Carburetor vs Fuel Injection

While both fuel injection and carburetors have been used in the aircraft industry for decades the debate continues on which is better. Cessna began using fuel injected 470 and 520 cu. in. engines in 1960 in Cessna 210's and Cessna 182's. As different models of aircraft were added to production they were equipped with fuel injected engines.

Cessna chose the Fuel Injected engines for horsepower and economy.


Fuel injection provides even distribution of the fuel to all cylinders since a fuel nozzle is placed in each cylinder and fed individually with a line from the flow divider valve. In carbureted engines the fuel is introduced into the induction system at the carburetor venturi thru a single nozzle and then must make its way along a circuitous route to be introduced into the cylinder for combustion. The result of this circuitous route is that some cylinders get excessive amount of fuel and some get an insufficient amount of fuel.


Fuel injection allows the engine to perform to its full potential. A Fuel injected engine from Continental will produce 300HP for both the IO-520 and the IO-550 engine. An engine built as an O-520 or O-550 engine is de-rated and will produce significantly less horsepower. A side note to the fuel injected vs carbureted discussion, Continental has never produced a carbureted O-520 or O-550 engine. Continental engineering determined that the most efficient was to operate the high horsepower engine is with fuel injection.


Beside a more efficient engine, another big advantage to fuel injection is the potential of carburetor ice is eliminated. Carb ice is caused by rapid expansion of air as it passes thru the venturi in the carburetor which in itself cause’s the air temperature to decrease. That temperature drop is enhanced by atomization of the fuel which is introduced to the air at the same point. On engine’s that have the carburetor suspended from the induction system like the O-470 and O-520 engines the creation of carb ice can be a significant problem. On days of high humidity and 50° F frost may form on the induction system just above the carburetor. Cessna 180’s and 182’s are actually approved in the owner’s handbook to operate with partial carb heat during takeoff, climb and cruise.


So what does Air Plains do to a Cessna 180 or 182 to change it from a carbureted O-470 engine to a fuel injected IO-550 engine? The airframe has some slight changes made to accommodate the change to fuel injection. The O-470 Engine is removed and replaced with 300HP IO-520 or IO-550 engine. Along with a factory remanufactured engine, Air Plains installs a new 2 or 3 blade propeller and propeller governor.


A fuel reservoir tank is added to provide a constant supply of fuel to engine in all attitudes. This fuel reservoir tank is installed in every Cessna single engine aircraft that has fuel injection installed. These would include restart 172’s, 182’s and 206’s.


Instead of beating on the firewall with a hammer to provide clearance for the high capacity oil pump and the engine driven fuel pump, Air Plains installs a small relief panel in the firewall. An electric fuel pump is added to the aircraft which aids starting and serves as a backup to the engine fuel pump. The result is a smooth running, fuel efficient engine system that is designed to give many years of safe operation. There are no excuses and no compromises with a fuel injected engine.


 

For more information, visit us at www.airplains.com

Call: 800-752-8481 or (outside the U.S.) +1-620-326-8904

Email: sales@airplains.com



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