Ever since 1970 Mitsubishi has used a four digit naming convention to identify their engines. The initial four digits may be supplemented with other suffixes to differentiate the engines even further but for the most part the first four digits are the main engine code.
The first digit in this series designates how many cylinders the engine has, for example: a 2 would mean it was a two cylinder, a 3 would mean it was a straight three cylinder, a 4 would make it an inline four cylinder, a 6 denotes a V6 configuration and an 8 identifies the engine as a v8.
From 1970 through 1980 the second letter stood for the fuel type, D was for diesel and G was for gasoline, in the 80’s this changed as Mitsubishi introduced the letter A to denote the use of an alloy cylinder head. This has since evolved with the use of M and B in certain engine codes so original conventions no longer apply.
The third digit used to denote the engine family the line derived from, for example the four cylinder engine families were denoted as follows: 4G1 was the Orion engine family, 4G3 was the Saturn engine family, 4G4 was the Neptune engine family, 4G5 was the Astron engine family and the 4G6 was from the Sirius engine family.
The fourth of these digits denotes the specific engine model within its family.
It is not unusual to see either a T or a B following the initial four digits. The T would denote the engine as being a turbo charged version and the B would denote the engine as being the second version of an engine.
Through the years Mitsubishi has used many different engine configurations, from one cylinder all the way up to eight cylinder configurations.
The single cylinder engines were the very first engines used in Mitsubishi vehicles which were motor scooters and three wheelers. The single cylinders were broken down as follows: the NE/NE1 which was side valve and air cooled, the NE10 which was in the famous Silver pigeon scooter. Later down the line other variants were introduced such as the NE7 the NE9 and the NE8 which was an overhead valve configuration. Then there was the ME20 which was a 309cc water cooled overhead valve engine which was equipped in the three wheeled Leo.
The Two cylinder configurations were commonly found in the 1960’s. They included the likes of the 2G1 which was first introduced in first generation Minicas in 1968. This was gradually replaced by the ME24 air cooled engine. That was then replaced by the 2G10. The NE19A was an air cooled 493cc overhead valve engine first introduced build an engine kit in the Mitsubishi 500. That was the first passenger car built by Mitsubishi after world war two. NE35A was a 594cc available in the Mitsubishi 500 and Mitsubishi Colt 600. The 2G2 Vulcan engine which was a four stroke overhead cam which was the predecessor to the 2G1.
The three cylinder engines produced by Mitsubishi are mainly designed for Japanese market Kei cars. The engines include codes such as the 3A9 used in the 2005 Colt, the 3B2 used in the 3002 Mitsubishi I, and the 3G8 which was the first production engine to feature five valves per cylinder.
The four cylinder engines produced by Mitsubishi fell into twelve different families. The 4A3 which was designed for Japanese Kei cars in 1994, the 4A9 which was introduced in the 2003 colt, the 4B1 which was developed alongside Daimler Chrysler and Hyundai and featured an aluminum engine block and Move variable valve timing, the 4DR which was produced as a turbo diesel engine, the 4G1 known as the Orion engine family, the 4G3 known as the Saturn engine family, the 4G4 known as the Neptune engine family, the 4G5 known as the Astron engine family, the 4G6 known as the Sirius engine family, the 4G9 which offered the first GDI or gasoline direct injection system, the 4M4 which was Mitsubishi replacement for the above mentioned Astron diesel engines, the 4N1 which is a clean burn diesel introduced in 2009 and the KE4 which was a overhead valve straight four used in late 60’s colts.