The Development of Fuel Injected Engines A Brief History

Every fuel injection system is designed specifically for the type of fuel it will handle, and models currently exist for gasoline, LPG (aka propane), diesel, ethanol, hydrogen, methane, and methanol, though the advent of EFI - electronic fuel injection - has made the hardware for gasoline and diesel systems essentially the same.

While the fuel in gasoline engines was metered with carburetors almost from the beginning, fuel injection technology has been widely used for other types of fuel since the 1880s, beginning with Frederick William Lanchester's first days at the Forward Gas Engine Company, in Birmingham England. Beginning in 1889, he conducted some of the first experiments with the technology, and his work was soon expanded upon by E. J. Pennington, who had included an extremely crude version of fuel injection in the patent for his motorcycle design in 1896. Not long after, Herbert Akroyd Stuart developed the first version of fuel injection to resemble modern systems. It used a "jerk pump" to measure out fuel oil at very high pressure, feeding it to an injector. The system was used on a hot bulb engine, and was later improved and adapted by Robert Bosch to replace Rudolf Diesel's original (and quite cumbersome) "air-blast" system on diesel engines.

By the 1920's fuel injection was widely used on diesel engines, and was being adapted for use in gasoline-powered aircraft because it was less susceptible to the unpredictable g-force changes on an airplane engine. Fuel injection would eventually be used during World War II on such planes as the Wright R-3350 and the B-29 Superfortress.

Fuel injection didn't really come into play on commercial gasoline engine systems until after the war had ended, and one of the earliest versions was a Bosch-developed design that was introduced in 1955 of the Mercedes-Benz 300SL. The Bosch system used a normal fuel pump, which provided fuel to an injection pump that was mechanically driven, and had separate plungers for each injector in order to provide a high-pressure injection directly into the engine's combustion chamber. Other Bosch variants on this system that involved injecting the fuel into a port above the intake valve were used in American versions of the Porsche 911 from 1969 to 1973, and on the European Carrera RS 2.7 and 3.0 street vehicles, until 1975. (Porsche would continue to use the same system on their racing cars until the early 1980s.)

During the same period that Bosch was working on his version of fuel injection technology, Chevrolet was also developing a fuel injection system. In 1957, they introduced (through GM's Rochester Products division) a mechanical fuel injection solution for the 283 V8 engine. Chevy's design involved directing inducted engine-air across a plunger (specifically a spoon-shaped plunger) that moved in proportion to the air volume. The plunger, in turn, was connected to the fuel metering system with dispensed fuel to the cylinders via mechanically controlled distribution tubes. Unlike other versions of fuel injection, Chevrolet's system used a constant flow of fuel that was metered from a spidery-looking collection of central injection lines, rather than an intermittent or "pulse" injection used by other developers.

Chevy's system adjusted the amount of fuel flow according to the engine's speed and load, and included a fuel reservoir which was not unlike the float chamber found in a carburetor. The system used its own high-pressure cable-driven pump to supply the required pressure for injection, but this was still "port" injection, in which the injectors were located within the intake manifold close to the intake valve. The highest performance version of this engine was rated at 283 hp, though it actually produced 290 hp.

A year later, in 1958, the first electronic version of fuel injection- a multi-point system with dual 2-bbl throttles, became available as an option on Chrysler products using both Hemi and wedge engines. This technology was jointly developed by Chrysler and Bendix The first factory electronic fuel injection, a true multi-point system, with dual 2-bbl. throttles, was optional on 1958 Chrysler products, both Hemi and wedge engines. It was jointly engineered by Chrysler and Bendix.

While many other versions of mechanical injection systems (including the Hilborn version which was frequently used on modified V8 engines for drag and oval racing) continued to be used through the 1960's, the first EFI system, known as the Electrojector, came into being in 1957, developed by the Bendix Corporation, and offered by American Motors in a special version of their Rambler Rebel muscle car. The engine was a 327 CID (5.4 liters) and the Electrojector option version provided 288 hp. Problems with suppliers delayed production of these cars to the point where the only fuel-injected Rebels weren't available until mid-1957, and then only pre-production cars were so-equipped. Nevertheless, the Rambler's EFI system was significantly more advanced than the mechanical systems offered by other companies, though it did have start-up difficulties in cold weather.

Chrysler (which had teamed up with Bendix for a mechanical fuel-injector), offered Electrojector versions of their 300 D, D500, and DeSoto Adventurer for the 1958 model year, but none of the electronic components were tough enough to sustain underhood service, and most cars sold with these systems were eventually retrofitted with 4-barrel carburetors, while the patents for the Electrojector were sold to Bosch, which developed an EFI system called D-Jetronic for use on the VW 1600TL in 1967.

Bosch continued to take the lead in the development of EFI technology, eventually using the D-Jetronic system, which used discrete analog electronics in combination with an electro-mechanical pressure sensor, and was ultimately used by Citroen, Mercedes-Benz, Porsche, Saab, and Volvo as well as VW. While the original system was eventually superseded by the K- and L-Jetronic systems during the early 1970s, Cadillacs used a GM-system that was eerily similar to the original D-Jetronic from 1977 on.

In 1982, Bosch introduced yet another design change, incorporating a sensor that could directly measure the air mass flow into an engine, into their LH-Jetronic model. The sensor used a heated platinum wire placed within the incoming air flow, and used the rate of cooling to determine the necessary injection flow. This was the first fully digital electronic fuel injection system, which became the standard approach.

With the advent of the digital microprocessor, it was possible to integrate all powertrain subsystems, including fuel injection, into a single control module. Today, fuel injection, and specifically electronic fuel injection, the technology for mixing air and fuel in an internal combustion engine, and has become the automotive design standard, almost completely replacing carburetors.

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