Finding the quickest, easiest path to a destination is nearly always the wisest and most efficient course. That elementary procedure works for engines, too. If the fuel/air mixture that lets the engine run can make its way—unimpeded—into each combustion chamber, it’s bound to be most efficient.
Direct Injection is the term that’s been tossed about a lot in the past few years. Just about every manufacturer that develops an engine with that configuration for the fuel/air flow strives to publicize the fact. As a result, Direct Injection has become quite a selling point, even among shoppers who aren’t exactly sure what it means. After all, something that’s “direct” as opposed to roundabout has to be good, right?
True enough, but it’s not a new idea. So, why didn’t the automakers start producing and marketing cars with direct injection years ago?
Cost and computers are the twin, closely related answers to that query. Not until computerization reached the point of controlling a precisely metered flow of fuel—and such a system could be manufactured at a reasonable price—did direct injection become a workable reality,
A primitive version was developed way back in 1898, by Deutz (an engine builder). The first production direct-injection system was introduced by Daimler-Benz for military aircraft, in the 1930s. During World War II, such systems saw use in B-29 bombers and other planes.
Mercedes-Benz claims credit for much of the early development of direct injection, and few seem prepared to dispute that claim. The first cars with direct injection appeared in the 1950s, led by the 1954 Mercedes-Benz 300 SL—the legendary “gullwing-door” coupe. Computers in those days were immense mainframe machines, and transistors were just beginning their assault on the electronics industry. So, all the early direct-injection systems were strictly mechanical.
In the 1960s, Ferrari F1 racers turned to direct injection. During the 1970s, electronic fuel injection finally pushed the old carburetors aside. As used during that decade and beyond, electronic injection was less complex and costly than true direct injection, but adequate for the requirements and regulations of the time. In addition, less change was needed in existing engines to adapt them to basic fuel injection.
Eventually, multi-point fuel injection began to supplant the early single-point setup. The injectors moved into the engine’s intake manifold—closer to each cylinder than before, but not quite there.
Late in the 1990s, some companies, including Mitsubishi, introduced direct injection on certain vehicles. As the 21st century began, some BMW, Audi, and Toyota models were turning to direct injection, which lets the engine mix fuel and air precisely when it’s required, in the most helpful proportion. The injector tips actually protrude into each combustion chamber. So, the precisely timed, carefully metered air/fuel mixture is ready just where and when it’s needed for the next explosion within the cylinder. Unused fuel is less likely to be sent out the exhaust as harmful emissions, during each engine cycle.
Like many technological developments, direct injection has come into gradual acceptance, initially on high-performance and luxury vehicles. During the last few years, however, it’s been expanding into quite a few mainstream models, including engines from GM, Ford, Hyundai, and quite a few other automakers. One of these days, the more elementary form of fuel injection will doubtless become extinct, just like the carburetor before it.
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