How does fuel injection work? This slow-mo video shows you
Fuel injection is often seen as one of those demarcations between older and newer cars, but the technology was invented as far back as the 1870s, and mass production of diesel-engined passenger cars meant fuel injection has been used in road cars since the 1930s.
Like a carburetor, it’s basically another way of atomizing fuel so it can be burned in an internal combustion engine. To see how it works, there’s probably no better demonstration than the latest slow-motion video from Smarter Every Day.
A couple of years back, host Destin Sandlin created a video demonstrating how carburetors work, using a rudimentary but custom-built see-through carb. In that video, slow-mo shots revealed how low-pressure intake air draws fuel into a venturi, at which point it’s broken into a fine mist and mixed with the air in the right ratio for combustion—with the help of a choke and a throttle valve.
The latest video is a little simpler, with Sandlin rigging up different types of fuel injectors with a friend and using a manual pump to send fuel through the fine nozzles at the tip of the injector.
Each of the injectors shown is taken from a tractor, with different types demonstrating different spray patterns that help or, in the case of older, more worn injectors, hinder combustion.
The really fascinating part though comes later in the video when Sandlin hooks up a blowtorch to set the fuel alight. While spectacular, it also gives an insight into the correct air-fuel mixture—the proper stoichiometric ratio, in chemistry speak—required for the fuel to combust. Note how when Sandlin first actuates the injector, the fuel closest to the flame is not the first to combust; ignition only occurs where the spray from the injector is fine enough to achieve the proper mix of the fuel and the air around it.
This video is just part one, with Sandlin promising a second video on the way going into more depth on direct injection, port injection, throttle bodies, and electronic injection. If it’s as informative as this one, we’re in for a treat.
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