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Posted by on Jul 30, 2017 in Tell Me Why |

Why Does an Automobile Have a Carburetor?

Why Does an Automobile Have a Carburetor?

An automobile is driven by an internal combustion engine which will work properly only if the right amounts of petrol and air are mixed together. The carburetor is the part of the engine where the mixing takes place. The burning of fuel in the engine is a chemical reaction in which petrol combines with the oxygen of the air to produce water, heat energy and oxides of carbon.

A chemically correct mixture should have fifteen parts of air to one part of petrol, both by weight. The amount of air then present is just sufficient to burn the petrol completely. If the engine uses a mixture with an excess of petrol–a rich mixture–a small amount of un-burnt petrol will be present in the exhaust fumes.

A carburetor has to produce the required mixture in varying strengths to suit different engine conditions, such as starting, idling, acceleration, cruising and application of full power. It must be able to pass the correct mixture at all engine speeds and under varying loads, and has to atomize the petrol into tiny droplets and vaporize the resulting spray into a combustible mixture.

Inside the carburetor is a throttle valve which can increase or decrease the amount of mixture passing into the cylinders, which in turn controls the power of the engine. This valve is mounted on a spindle which is operated by the accelerator pedal. A special device called a “strangler” or choke is also incorporated to help in starting the engine in cold weather by allowing an extra-rich mixture.

A carburetor or carburettor is a device that blends air and fuel for an internal combustion engine in the proper ratio for combustion. It is sometimes colloquially shortened to carb in North America or carby in Australia. To carburate or carburet (and thus carburation or carburetion, respectively) is to blend the air and fuel or to equip (an engine) with a carburetor for that purpose. Carburetors have largely been supplanted in the automotive and, to a lesser extent, aviation industries by fuel injection. They are still common on small engines for lawn mowers, rototillers and other equipment.

The first carburetor was invented by Samuel Morey in 1826. A carburetor was invented by an Italian, Luigi De Cristoforis, in 1876. Another carburetor was developed by Enrico Bernardi at the University of Padua in 1882, for his Motrice Pia, the first petrol combustion engine (one cylinder, 121.6 cc) prototyped on 5 August 1882. A carburetor was among the early patents by Karl Benz (1888) as he developed internal combustion engines and their components.

Early carburetors were the surface carburetor type, in which air is charged with fuel by being passed over the surface of gasoline. In 1885, Wilhelm Maybach and Gottlieb Daimler developed a float carburetor for their engine based on the atomizer nozzle. The Daimler-Maybach carburetor was copied extensively, leading to patent lawsuits, but British courts rejected the Daimler company’s claim of priority in favor of Edward Butler’s 1884 spray carburetor used on his Petrol Cycle.

Hungarian engineers János Csonka and Donát Bánki patented a carburetor for a stationary engine in 1893. Frederick William Lanchester of Birmingham, England, experimented with the wick carburetor in cars. In 1896, Frederick and his brother built the first gasoline-driven car in England: a single cylinder 5 hp (3.7 kW) internal combustion engine with chain drive. Unhappy with the performance and power, they re-built the engine the next year into a two-cylinder horizontally opposed version using his new wick carburetor design.

US-made gasoline-fueled engines

Carburetors were the usual method of fuel delivery for most US-made gasoline-fueled engines up until the late 1980s, when fuel injection became the preferred method. This change was dictated more by the requirements of catalytic converters than by any inherent inefficiency of carburation; a catalytic converter requires much more precise control over the fuel / air mixture, to closely control the amount of oxygen in the exhaust gases. In the U.S. market, the last carbureted cars were:

  • 1990 (General public) : Oldsmobile Custom Cruiser, Buick Estate Wagon, Cadillac Brougham, Honda Prelude (Base Model), Subaru Justy
  • 1991 (Police) : Ford Crown Victoria Police Interceptor with the 5.8 L (351 cu in) V8 engine.
  • 1991 (SUV) : Jeep Grand Wagoneer with the AMC 360 cu in (5.9 L) V8 engine.
  • 1993 Mazda B2200 (Light Truck)
  • 1994 (Light truck) : Isuzu

In Australia, some cars continued to use carburetors well into the 1990s; these included the Honda Civic (1993), the Ford Laser (1994), the Mazda 323 and Mitsubishi Magna sedans (1996), the Daihatsu Charade (1997), and the Suzuki Swift (1999). Low-cost commercial vans and 4WDs in Australia continued with carburetors even into the 2000s, the last being the Mitsubishi Express van in 2003. Elsewhere, certain Lada cars used carburetors until 2006. Many motorcycles still use carburetors for simplicity’s sake, since a carburetor does not require an electrical system to function. Carburetors are also still found in small engines and in older or specialized automobiles, such as those designed for stock car racing, though NASCAR’s 2011 Sprint Cup season was the last one with carbureted engines; electronic fuel injection was used beginning with the 2012 race season in Cup.

In Europe, carburetor-engined cars were being gradually phased out by the end of the 1980s in favor of fuel injection, which was already the established type of engine on more expensive vehicles including luxury and sports models. EEC legislation required all vehicles sold and produced in member countries to have a catalytic converter after December 1992. This legislation had been in the pipeline for some time, with many cars becoming available with catalytic converters or fuel injection from around 1990.

However, some versions of the Peugeot 106 were sold with carburettor engines from its launch in 1991, as were versions of the Renault Clio and Nissan Primera (launched in 1990) and initially all versions of Ford Fiesta range except the XR2i when it was launched in 1989. Luxury car manufacturer Mercedes-Benz had been producing mechanically fuel-injected cars since the early 1950s, while the first mainstream family car to feature fuel injection was the Volkswagen Golf GTI in 1976. Ford’s first fuel-injected car was the Ford Capri RS 2600 in 1970. General Motors launched its first fuel-injected car around the same time, when it began to introduce fuel-injected engines to its Vauxhall Cavalier/Opel Ascona range. Saab switched to fuel injection across its whole range from 1982.

Content for this question contributed by Kelly Maynard, resident of Springfield, Hampden County, Massachusetts, USA