Gasoline direct injection (GDI), also known as petrol direct injection (PDI), is a mixture formation system for
internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...
s that run on
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
(petrol), where
fuel is injected into the
combustion chamber
A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process.
Interna ...
. This is distinct from
manifold fuel injection systems, which inject fuel into the
intake manifold
In automotive engineering, an inlet manifold or intake manifold (in American English) is the part of an engine that supplies the fuel/air mixture to the cylinders. The word ''manifold'' comes from the Old English word ''manigfeald'' (from the ...
.
The use of GDI can help increase engine efficiency and specific power output as well as reduce exhaust emissions.
The first GDI engine to reach production was introduced in 1925 for a low-compression truck engine. Several German cars used a Bosch mechanical GDI system in the 1950s, however usage of the technology remained rare until an electronic GDI system was introduced in 1996 by Mitsubishi for mass-produced cars. GDI has seen rapid adoption by the automotive industry in recent years, increasing in the United States from 2.3% of production for model year 2008 vehicles to approximately 50% for model year 2016.
Operating principle
Charge modes
The 'charge mode' of a direct-injected engine refers to how the fuel is distributed throughout the combustion chamber:
* 'Homogeneous charge mode' has the fuel mixed evenly with the air throughout the combustion chamber, as per manifold injection.
*
Stratified charge mode has a zone with a higher density of fuel around the spark plug, and a leaner mixture (lower density of fuel) further away from the spark plug.
Homogeneous charge mode
In the ''homogeneous charge mode'', the engine operates on a homogeneous air/fuel mixture (
), meaning, that there is an (almost) perfect mixture of fuel and air in the cylinder. The fuel is injected at the very beginning of the intake stroke in order to give injected fuel the most time to mix with the air, so that a homogeneous air/fuel mixture is formed.
[Konrad Reif (ed.): ''Ottomotor-Management''. 4th edition, Springer, Wiesbaden 2014, p. 123] This mode allows using a conventional
three-way catalyst
A catalytic converter is an exhaust emission control device that converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalyzing a redox reaction. Catalytic converters are usually ...
for exhaust gas treatment.
[Konrad Reif (ed.): ''Ottomotor-Management''. 4th edition, Springer, Wiesbaden 2014, p. 121]
Compared with manifold injection, the
fuel efficiency
Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
is only very slightly increased, but the specific power output is better, which is why the homogeneous mode is useful for so-called
engine downsizing In the automotive industry, engine downsizing is the practice of utilizing smaller combustion engines over larger ones of the same power capacity when manufacturing vehicles. It is the result of car manufacturers attempting to provide more efficient ...
.
Most direct-injected passenger car petrol engines use the homogeneous charge mode.
Stratified charge mode
The ''stratified charge mode'' creates a small zone of fuel/air mixture around the spark plug, which is surrounded by air in the rest of the cylinder. This results in less fuel being injected into the cylinder, leading to very high overall air-fuel ratios of
, with mean air-fuel ratios of
at medium load, and
at full load. Ideally, the throttle valve remains open as much as possible to avoid throttling losses. The torque is then set solely by means of quality torque controlling, meaning that only the amount of injected fuel, but not the amount of intake air is manipulated in order to set the engine's torque. Stratified charge mode also keeps the flame away from the cylinder walls, reducing the thermal losses.
Since mixtures too lean cannot be ignited with a spark-plug (due to a lack of fuel), the charge needs to be stratified (e. g. a small zone of fuel/air mixture around the spark plug needs to be created). To achieve such a charge, a stratified charge engine injects the fuel during the latter stages of the compression stroke. A "swirl cavity" in the top of the piston is often used to direct the fuel into the zone surrounding the
spark plug
A spark plug (sometimes, in British English, a sparking plug, and, colloquially, a plug) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air ...
. This technique enables the use of ultra-lean mixtures that would be impossible with carburetors or conventional manifold fuel injection.
The stratified charge mode (also called "ultra lean-burn" mode) is used at low loads, in order to reduce fuel consumption and exhaust emissions. However, the stratified charge mode is disabled for higher loads, with the engine switching to the homogeneous mode with a
stoichiometric air-fuel ratio of
for moderate loads and a richer air-fuel ratio at higher loads.
In theory, a stratified charge mode can further improve fuel efficiency and reduce exhaust emissions, however, in practice, the stratified charge concept has not proved to have significant efficiency advantages over a conventional homogeneous charge concept, but due to its inherent lean burn, more
nitrogen oxides Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:
Charge-neutral
*Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide
*Nitrogen dioxide (), nitrogen(IV) oxide
*Nitrogen trioxide (), or ni ...
are formed, which sometimes require a
NOx adsorber
A adsorber or trap (also called Lean trap, abbr. LNT) is a device that is used to reduce oxides of nitrogen (NO and NO2) emissions from a lean burn internal combustion engine by means of adsorption.
Purpose and function of a adsorber
A adsor ...
in the exhaust system to meet emissions regulations. The use of NOx adsorbers can require low sulphur fuels, since sulphur prevents NOx adsorbers from functioning properly. GDI engines with stratified fuel injection can also produce higher quantities of
particulate matter
Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM) or suspended particulate matter (SPM) – are microscopic particles of solid or liquid matter suspended in the air. The ter ...
than manifold injected engines, sometimes requiring particulate filters in the exhaust (similar to a
diesel particulate filter
A diesel particulate filter (DPF) is a device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine.Tom Nash (May 2003) "Diesels: The Smoke is clearing", ''Motor '' Vol.199 No. 5, p. 54, Hearst Business Publ ...
) in order to meet vehicle emissions regulations. Therefore several European car manufacturers have abandoned the stratified charge concept or never used it in the first place, such as the 2000 Renault 2.0 IDE petrol engine (
F5R), which never came with a stratified charge mode, or the 2009
BMW N55
The BMW N55 is a turbocharged straight-six petrol engine that began production in 2009. The N55 replaced the BMW N54 engine and was introduced in the F07 5 Series Gran Turismo.
The N55 was BMW's first straight-six engine to use a twin-scroll t ...
and 2017
Mercedes-Benz M256 engines dropping the stratified charge mode used by their predecessors. The Volkswagen Group had used fuel stratified injection in naturally aspirated engines labelled ''FSI'', however, these engines have received an engine control unit update to disable the stratified charge mode. Turbocharged Volkswagen engines labelled ''TFSI'' and ''TSI'' have always used the homogeneous mode. Like the latter VW engines, newer direct injected petrol engines (from 2017 onwards) usually also use the more conventional homogeneous charge mode, in conjunction with variable valve timing, to obtain good efficiency. Stratified charge concepts have mostly been abandoned.
Injection modes
Common techniques for creating the desired distribution of fuel throughout the combustion chamber are either ''spray-guided'', ''air-guided'', or ''wall-guided'' injection. The trend in recent years is towards spray-guided injection, since it currently results in a higher fuel efficiency.
Wall-guided direct injection
In engines with wall-guided injection, the distance between spark plug and injection nozzle is relatively high. In order to get the fuel close to the spark plug, it is sprayed against a swirl cavity on top of the piston (as seen in the picture of the Ford EcoBoost engine on the right), which guides the fuel towards the spark plug. Special swirl or tumble air intake ports aid this process. The injection timing depends upon the piston speed, therefore, at higher piston speeds, the injection timing, and ignition timing need to be advanced very precisely. At low engine temperatures, some parts of the fuel on the relatively cold piston cool down so much, that they cannot combust properly. When switching from low engine load to medium engine load (and thus advancing the injection timing), some parts of the fuel can end up getting injected behind the swirl cavity, also resulting in incomplete combustion. Engines with wall-guided direct injection can therefore suffer from high
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
emissions.
Air-guided direct injection
Like in engines with wall-guided injection, in engines with air-guided injection, the distance between spark plug and injection nozzle is relatively high. However, unlike in wall-guided injection engines, the fuel does not get in contact with (relatively) cold engine parts such as cylinder wall and piston. Instead of spraying the fuel against a swirl cavity, in air-guided injection engines the fuel is guided towards the spark plug solely by the intake air. The intake air must therefore have a special swirl or tumble movement in order to direct the fuel towards the spark plug. This swirl or tumble movement must be retained for a relatively long period of time, so that all of the fuel is getting pushed towards the spark plug. This however reduces the engine's charging efficiency and thus power output. In practice, a combination of air-guided and wall-guided injection is used. There exists only one engine that only relies on air-guided injection.
Spray-guided direct injection
In engines with spray-guided direct injection, the distance between spark plug and injection nozzle is relatively low. Both the injection nozzle and spark plug are located in between the cylinder's valves. The fuel is injected during the latter stages of the compression stroke, causing very quick (and inhomogeneous) mixture formation. This results in large fuel stratification gradients, meaning that there is a cloud of fuel with a very low air ratio in its centre, and a very high air ratio at its edges. The fuel can only be ignited in between these two "zones". Ignition takes place almost immediately after injection to increase engine efficiency. The spark plug must be placed in such a way, that it is exactly in the zone where the mixture is ignitable. This means that the production tolerances need to be very low, because only very little misalignment can result in drastic combustion decline. Also, the fuel cools down the spark plug, immediately before it is exposed to combustion heat. Thus, the spark plug needs to be able to withstand thermal shocks very well. At low piston (and engine) speeds, the relative air/fuel velocity is low, which can cause fuel to not vaporise properly, resulting in a very rich mixture. Rich mixtures do not combust properly, and cause carbon build-up. At high piston speeds, fuel gets spread further within the cylinder, which can force the ignitable parts of the mixture so far away from the spark plug, that it cannot ignite the air/fuel mixture anymore.
Companion technologies
Other devices which are used to complement GDI in creating a stratified charge include
variable valve timing
In internal combustion engines, variable valve timing (VVT) is the process of altering the timing of a valve lift event, and is often used to improve performance, fuel economy or emissions. It is increasingly being used in combination with varia ...
,
variable valve lift
Variable valve lift (VVL) is an automotive piston engine technology which varies the height a valve opens in order to improve performance, fuel economy or emissions. There are two main types of VVL: discrete, which employs fixed valve lift amounts, ...
, and
variable length intake manifold
In internal combustion engines, a variable-length intake manifold (VLIM),variable intake manifold (VIM), or variable intake system (VIS) is an automobile internal combustion engine manifold technology. As the name implies, VLIM/VIM/VIS can vary ...
. Also,
exhaust gas recirculation
In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide () emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. EGR works by recirculating a portion of an engine's exhaust ...
can be used to reduce the high nitrogen oxide (NOx) emissions that can result from the ultra lean combustion.
Disadvantages
Gasoline direct injection does not have the valve cleaning action that is provided when fuel is introduced to the engine upstream of the cylinder. In non-GDI engines, the gasoline traveling through the intake port acts as a cleaning agent for contamination, such as atomized oil. The lack of a cleaning action can cause increased carbon deposits in GDI engines. Third party manufacturers sell
oil catch tanks which are supposed to prevent or reduce those carbon deposits.
The ability to produce peak power at high engine speeds (RPM) is more limited for GDI, since there is a shorter period of time available to inject the required quantity of fuel. In manifold injection (as well as carburetors and throttle-body fuel injection), fuel can be added to the intake air mixture at any time. However a GDI engine is limited to injecting fuel during the intake and compression phases. This becomes a restriction at high engine speeds (RPM), when the duration of each combustion cycle is shorter. To overcome this limitation, some GDI engines (such as the
Toyota ''2GR-FSE'' V6 and
Volkswagen ''EA888'' I4 engines) also have a set of manifold fuel injectors to provide additional fuel at high RPM. These manifold fuel injectors also assist in cleaning carbon deposits from the intake system.
Gasoline does not provide the same level of lubrication for the injector components as diesel, which sometimes becomes a limiting factor in the injection pressures used by GDI engines. The injection pressure of a GDI engine is typically limited to approximately , to prevent excessive wear on the injectors.
Adverse climate and health impacts
While this technology is credited with boosting fuel efficiency and reducing CO
2 emissions, GDI engines produce more black carbon aerosols than traditional port fuel injection engines. A strong absorber of solar radiation, black carbon possesses significant climate-warming properties.
In a study published in January 2020 in the journal ''Environmental Science and Technology'', a team of researchers at the University of Georgia (USA) predicted that the increase in black carbon emissions from GDI-powered vehicles will increase climate warming in urban areas of the U.S. by an amount that significantly exceeds the cooling associated with a reduction in CO
2. The researchers also believe the shift from traditional port fuel injection (PFI) engines to the use of GDI technology will nearly double the premature mortality rate associated with vehicle emissions, from 855 deaths annually in the United States to 1,599. They estimate the annual social cost of these premature deaths at $5.95 billion.
History
1911-1912
One of the early inventors trying gasoline direct injection was Dr
Archibald Low who gave his engine the misleading title of ''Forced Induction Engine'' whereas it was only the admission of the fuel that was forced. He revealed details of his prototype engine early in 1912, and the design was further developed by the large scale engine builder
F.E. Baker Ltd
F. E. Baker Ltd was a British motorcycle engine and cyclecar engine manufacturer based in the Precision Works, Moorsom Street, Birmingham, England. Founded in 1906 by Frank Edward Baker, the company produced motorcycle engines under the Precisi ...
during 1912 and the results displayed on their stand at the Olympia Motor Cycle show in November 1912. The engine was a high compression four-stroke motorcycle engine, with the gasoline fuel separately pressurised to 1000psi and admitted into the cylinder 'at the moment of highest compression' by a small rotary valve, with simultaneous ignition by a spark plug and trembler coil allowing sparking to continue throughout the combustion phase. The fuel being injected was described as being in vapour phase having been heated by the engine cylinder. The pressure of the fuel was regulated at the fuel pump, and the amount of fuel admitted was controlled by mechanical means at the rotary admission valve. It seems this radical design wasn't taken further by F.E. Baker.
1916-1938
Although direct injection has only become commonly used in gasoline engines since 2000,
diesel engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...
s have used fuel directly injected into the combustion chamber (or a pre-combustion chamber) since the first successful prototype in 1894.
An early prototype of a GDI engine was built in Germany in 1916 for the
Junkers
Junkers Flugzeug- und Motorenwerke AG (JFM, earlier JCO or JKO in World War I, English: Junkers Aircraft and Motor Works) more commonly Junkers , was a major German aircraft and aircraft engine manufacturer. It was founded there in Dessau, Germ ...
airplane. The engine was initially designed as a diesel engine, however it switched to being designed for gasoline when the German ministry of war decreed that aircraft engines must run on either gasoline or benzene. Being a
crankcase-compression two-stroke design, a misfire could destroy the engine, therefore Junkers developed a GDI system to prevent this issue. A demonstration of this protype engine to aviation officials was performed shortly before development ceased due to the end of World War I.
The first direct injection engine to use gasoline (amongst other fuels) to reach production was the 1925-1947
Hesselman engine
The Hesselman engine is a hybrid between a petrol engine and a Diesel engine. It was designed and introduced in 1925 by Sweden, Swedish engineer Jonas Hesselman (1877-1957). It represented the first use of direct Gasoline direct injection, gaso ...
which was built in Sweden for trucks and buses. As a hybrid between an
Otto cycle
An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle most commonly found in automobile engines.
The Otto cycle is a description of what happ ...
and a
Diesel cycle
The Diesel cycle is a combustion process of a reciprocating internal combustion engine. In it, fuel is ignited by heat generated during the compression of air in the combustion chamber, into which fuel is then injected. This is in contrast to ign ...
engine, it could be run on a variety of fuels including gasoline and fuel oils. The Hesselman engines used the ultra lean burn principle and injected the fuel at the end of the compression stroke and then ignited it with a spark plug. Due to its low compression ratio, the Hesselman engine could run on cheaper heavy fuel oils, however the incomplete combustion resulted in large amounts of smoke.
1939-1995
During World War II, most of the German aircraft engines used GDI, such as the
BMW 801
The BMW 801 was a powerful German air-cooled 14-cylinder-radial aircraft engine built by BMW and used in a number of German Luftwaffe aircraft of World War II. Production versions of the twin-row engine generated between 1,560 and 2,000 PS ( ...
radial engine, the German inverted V12
Daimler-Benz DB 601
The Daimler-Benz DB 601 was a German aircraft engine built during World War II. It was a liquid-cooled inverted V12 engine, V12, and powered the Messerschmitt Bf 109, Messerschmitt Bf 110, and many others. Approximately 19,000 601's were pr ...
,
DB 603
The Daimler-Benz DB 603 was a German aircraft engine used during World War II. It was a liquid-cooled 12-cylinder inverted V12 enlargement of the DB 601, which was in itself a development of the DB 600. Production of the DB 603 commenced in ...
and
DB 605
The Daimler-Benz DB 605 is a German aircraft engine built during World War II. Developed from the DB 601, the DB 605 was used from 1942 to 1945 in the Messerschmitt Bf 109 fighter, and the Bf 110 and Me 210C heavy fighters.
The DB 610, a p ...
engines, and the similar-layout
Junkers Jumo 210G
The Jumo 210 was Junkers Motoren's first production inverted V12 gasoline aircraft engine, first produced in the early 1930s. Depending on the version it produced between 610 and 730 PS and can be considered a counterpart of the Rolls-Royce Kest ...
,
Jumo 211
The Jumo 211 was a German inverted V-12 aircraft engine, Junkers Motoren's primary aircraft engine of World War II. It was the direct competitor to the Daimler-Benz DB 601 and closely paralleled its development. While the Daimler-Benz engi ...
and
Jumo 213
The Junkers Jumo 213 was a World War II-era V12 engine, V-12 liquid-cooled aircraft engine, a development of Junkers Motoren's earlier design, the Junkers Jumo 211, Jumo 211. The design added two features, a pressurized cooling system that requir ...
inverted V12 engines.
Allied
An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...
aircraft engines that used GDI fuel injection systems were the Soviet Union
Shvetsov ASh-82FNV radial engine and the American 54.9 litre displacement
Wright R-3350
The Wright R-3350 Duplex-Cyclone is an American twin-row, supercharged, air-cooled, radial aircraft engine with 18 cylinders displacing nearly . Power ranged from 2,200 to over 3,700 hp (1,640 to 2,760 kW), depending on the model. ...
''Duplex Cyclone'' 18-cylinder radial engine.
The German company
Bosch had been developing a mechanical GDI system for cars since the 1930s
and in 1952 it was introduced on the two-stroke engines in the
Goliath GP700
The Goliath GP700 is a small automobile which was manufactured by the Bremen, Germany–based Borgward subsidiary Goliath (car), Goliath-Werke Borgward & Co from 1950 to 1957. In 1955, the GP700 was joined by the larger-engined Goliath GP900 E. F ...
and
Gutbrod Superior
The Gutbrod Superior is a small car, built from 1950 until 1954 by German manufacturer Gutbrod. A total of 6,860 cabriolet saloons and 866 estates were built in less than four years.
History
In November 1949, a pilot series of the cabriole ...
. This system was basically a high-pressure diesel direct-injection pump with an intake throttle valve set up. These engines gave good performance and had up to 30% less fuel consumption over the carburetor version, primarily under low engine loads.
An added benefit of the system was having a separate tank for the engine oil which was automatically added to the fuel mixture, obviating the need for owners to mix their own two-stroke fuel blend. The 1955
Mercedes-Benz 300SL
The Mercedes-Benz 300 SL (chassis code W 198) is a two-seat sports car which was produced by Mercedes-Benz as a gullwinged coupe (1954–1957) and roadster (1957–1963).Werner Oswald: ''Mercedes-Benz Personenwagen 1945–1985''. Motorbuch Ve ...
also used an early Bosch mechanical GDI system, therefore becoming the first four-stroke engine to use GDI. Up until the mid-2010s, most fuel-injected cars used manifold injection, making it quite unusual that these early cars used an arguably more advanced GDI system.
During the 1970s, the United States manufacturers
American Motors Corporation
American Motors Corporation (AMC; commonly referred to as American Motors) was an American automobile manufacturing company formed by the merger of Nash-Kelvinator Corporation and Hudson Motor Car Company on May 1, 1954. At the time, it was the ...
and
Ford
Ford commonly refers to:
* Ford Motor Company, an automobile manufacturer founded by Henry Ford
* Ford (crossing), a shallow crossing on a river
Ford may also refer to:
Ford Motor Company
* Henry Ford, founder of the Ford Motor Company
* Ford F ...
developed prototype mechanical GDI systems called ''Straticharge'' and ''Programmed Combustion'' (PROCO) respectively. Neither of these systems reached production.
1997-present
The 1996 Japanese-market
Mitsubishi Galant
The Mitsubishi Galant is an automobile which was produced by Japanese manufacturer Mitsubishi from 1969 until 2012. The model name was derived from the French word ''galant'', meaning "chivalrous". There have been nine distinct generations with ...
was the first mass-produced car to use a GDI engine, when a GDI version of the
Mitsubishi 4G93 inline-four engine was introduced. It was subsequently brought to Europe in 1997 in the
Carisma. It also developed the first six-cylinder GDI engine, the
Mitsubishi 6G74 V6 engine, in 1997. Mitsubishi applied this technology widely, producing over one million GDI engines in four families by 2001. Although in use for many years, on 11 September 2001 MMC claimed a trademark for the acronym 'GDI'. Several other Japanese and European manufacturers introduced GDI engines in the following years. The Mitsubishi GDI technology was also licensed by Peugeot, Citroën, Hyundai, Volvo and Volkswagen.
The 2005
Toyota 2GR-FSE V6 engine was the first to combines both direct and indirect injection. The system (called "D4-S") uses two fuel injectors per cylinder: a traditional manifold fuel injector (low pressure) and a direct fuel injector (high-pressure) and is used in most Toyota engines.
In Formula One racing, direct injection was made compulsory for the
2014 season, with regulation 5.10.2 stating: "There may only be one direct injector per cylinder and no injectors are permitted upstream of the intake valves or downstream of the exhaust valves."
In two-stroke engines
There are additional benefits of GDI for
two-stroke engine
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of t ...
s, relating to scavenging of the exhaust gases and lubrication of the crankcase.
The
scavenging
Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding ...
aspect is that most two-stroke engines have both the intake and exhaust valves open during the exhaust stroke, in order to improve the flushing of exhaust gases from the cylinder. This results in some of the fuel/air mixture entering the cylinder and then exiting the cylinder, unburned, through the exhaust port. With direct injection, only air (and usually some oil) comes from the crankcase, and fuel is not injected until the piston rises and all ports are closed.
Crankcase lubrication is achieved in two-stroke GDI engines by injecting oil into the crankcase, resulting in a lower oil consumption than the older method of injecting oil mixed with fuel into the crankcase.
Two types of GDI are used in two-strokes: low-pressure air-assisted, and high-pressure. The low-pressure systems— as used on the 1992
Aprilia SR50
The Aprilia SR50 is a scooter built by Aprilia.
History
Introduced in 1992, more than 800,000 units have been sold, bucking the trend for less use of two-stroke engines. Aprilia claims several firsts for the SR50 in the scooter market, includi ...
motor scooter— uses a crankshaft-driven air compressor to inject air into the cylinder head. A low-pressure injector then sprays fuel into the combustion chamber, where it vaporizes as it mixes with the compressed air. A high-pressure GDI system was developed by German company Ficht GmbH in the 1990s and introduced for marine engines by
Outboard Marine Corporation
Outboard Marine Corporation (OMC) was a maker of Evinrude, Johnson and Gale Outboard Motors, and many different brands of boats. It was a multibillion-dollar Fortune 500 corporation. Evinrude began in Milwaukee, Wisconsin in 1907. OMC was based ...
(OMC) in 1997, in order to meet stricter emissions regulations. However, the engines had reliability problems and OMC declared bankruptcy in December 2000. The ''Evinrude E-Tec'' is an improved version of the Ficht system, which was released in 2003 and won an EPA ''Clean Air Excellence'' Award in 2004.
Envirofit International
Envirofit International is an American non-profit organization that develops technology for reducing air pollution and enhancing energy efficiency in developing nations.
Envirofit's most significant products have been affordable clean burning stov ...
, an American non-profit organisation, has developed direct injection retrofit kits for two-stroke motorcycles (using technology developed by
Orbital Corporation Limited
Orbital Corporation Limited (), formerly Orbital Engine Corporation Limited pioneered by Ralph Sarich, is an Australian company based in Balcatta, Western Australia, that aims to provide clean engine technologies and alternative fuel systems ...
) in a project to reduce air pollution in Southeast Asia. The 100-million two-stroke taxis and motorcycles in Southeast Asia are a major cause of pollution for the region.
See also
*
Common rail
Common rail direct fuel injection is a direct fuel injection system built around a high-pressure (over ) fuel rail feeding solenoid valves, as opposed to a low-pressure fuel pump feeding unit injectors (or pump nozzles). High-pressure injection ...
*
Diesel engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...
*
Fuel injection
Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines.
All comp ...
*
Gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
References
{{DEFAULTSORT:Gasoline Direct Injection
Fuel injection systems
Internal combustion piston engines