Second Chance Garage
All About Car Restoration
Second Chance Garage
All About Car Restoration


A Short History Of Fuel Injection

Fuel Injection isn't new technology. It's been around for nearly as long as the auto industry, although crudeness, unreliability and cost made it economically impractical for mainstream automobiles until the 1980s. Simply put, fuel doesn't burn efficiently unless it is atomized into as perfect a cloud as possible. Early engines used nothing more sophisticated than a controlled drip into the cylinders, and the advent of the carburetor helped advance internal combustion practicality. The carburetor soldiered on for at least 80 years but its limitations (poor atomization, inability to alter mixture precisely according to engine conditions, high emissions, etc.) made it obsolete for modern requirements. Fuel injection was the only answer.

An early patent for fuel injection dates from 1896 but little work was done until Robert Bosch developed workable systems for use on diesel engines. By the 1920s it was widely used on diesels and during the 30s German engineers developed fuel injection for gas engines used in fighter aircraft. They were very effective in World War II because German fighters didn't suffer from "g" force effects that limited performance on carbureted engines. Because they were mechanical they were also incredibly complicated, with one fuel pump for each cylinder (up to 14!) and hundreds of parts.

Learning lessons from the superiority of fuel injected German fighter airplanes during World War II, Bendix Aviation developed the first electronic fuel injection for aircraft used in the Korean War. It worked pretty well, mainly because the military could afford the expensive components required for reliable operation. Also, the Bendix system was relatively simple because aircraft engines only operated at idle or full throttle. It was far too expensive for automotive use, however.

Mercedes-Benz used an effective Bosch fuel injection system in its legendary 300SL cars and these mechanical units eventually found their way into Porsche cars. In the US GM's Rochester division had developed its own mechanical fuel injection and first used it in the 1957 Chevrolet cars, most notably Corvette. It was a highly complex device that measured airflow across a plunger that was connected to a metering system through distribution tubes. Rochester used a port-type injection system that fed high-pressure fuel to injector nozzles inside the intake manifold and managed to yield 290 horsepower out of the 283 cubic-inch engines.

Drag and oval racing fans will remember the Hilborn mechanical injection systems that first appeared on Ford engines and then were widely used throughout the 1960s. These were similar to older injection systems in that the main application was wide-open throttle.

Meanwhile Chrysler and Bendix teamed to make the Electrojector fuel injection systems for automobiles. Engineers came up with a complex system that included two dual-point distributors. One ran the fuel injection and the other the ignition. An electric fuel pump moved gas to the injectors and two electronics boxes were mounted to the car's radiator. One was a resistance box and the other an electronic modulator, and both used early transistors along with old style resistors and capacitors. Air entered the engines through dual 2-barrel throttles for optimal flow.

Heat was the enemy of electronic circuitry back then and you can imagine the problems that occurred in automobile engine compartments. Chrysler only made a few dozen cars fitted with fuel injection during the late 1950s and they were so trouble-prone that most were refitted with carburetors. Original fuel injected Chryslers and DeSoto's from the late 50s are highly collectible today. Even rarer would be the few pre-production Rambler Rebel models that were built with the Electrojector system.

Still, the Bendix approach was the best one. The Bendix systems had early versions of many components used on modern injection systems including fuel pressure regulation, individual injectors, throttle positioning sensing, cold-start and warmup sensing, vacuum, temperature and air sensors and several others. The "brain" of the Electrojector was a modulator that collected all the information from sensors and converted it into a signal to actuate the injectors, just as today's systems do. Its engineers stated that it would increase horsepower by 10-20, increase fuel economy and reduce exhaust pollution. Detroit never did well selling fuel injection as an engine option and Rochester sold its technology to Bendix. Bendix sold its rights to Bosch and that company continued development throughout the 1970s, eventually calling it the Jetronic. They made the right choice, as emissions regulations and rapidly-escalating advances in electronics (most notably the microprocessor) made fuel injection reliable and affordable for manufacturers. Bosch produced the first fully digital electronic injection system in 1982.

Today's engine management systems combine all the functions (ignition, timing, cooling, fuel delivery) into computer-controlled operations that work incredibly well, allowing engines to develop maximum power with minimum fuel. When you next get into your cold car and are able to instantly start your engine and drive away smoothly, give a thanks to those who developed fuel injection. Without them we'd still be setting chokes, cranking incessantly, warming the engines for several minutes and stalling at stop signs, not to mention belching out smoke and pollution.

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