Figured I'd post this just for the hell of it. Comes in handy sometimes.

Numerical Prefix -

4 = four cylinder

6 = six cylinder

Numerical Suffix -

12 = 2.0 litre

13 = 2.5 litre

36 = 2.0 litre

54 = 2.6 litre

61 = 1.6 litre

62 = 1.85 litre

63 = 2.0 litre

64 = 2.4 litre

72 = 3.0 litre

73 = 2.5 litre

74 = 3.5 litre

91 = 1.5 litre

92 = 1.6 litre

93 = 1.8 litre

Power Output

Sixes
6G74 3.5 DOHC turbo 194kW
6G74 3.5 DOHC 194kW
6G72 3.0 DOHC twin turbo 209kW
6G72 3.0 DOHC 179kW/127kW
6G73 2.5 DOHC 131kW
6A12 2.0 DOHC MIVEC 149kW
6A12 2.0 DOHC turbo 149kW
6A12 2.0 DOHC 127kW

Fours
4G63 2.0 DOHC turbo 164kW
G63B DASH 2.0 SOHC 12 valve turbo 149kW
G63B 2.0 SOHC turbo 131kW
G62B 1.85 litre SOHC turbo 119kW
4G64 2.4 SOHC 108kW
G54B 2.6 SOHC turbo 131kW
4G91 1.5 DOHC 86kW
4G92 1.6 DOHC MIVEC 131kW
4G93 1.8 DOHC 112kW
4G93 1.8 DOHC turbo 145kW
4G36 2.0 DOHC 104kW
4G61 1.6 DOHC turbo 108kW

The numbers arent a key to the displacement of engine

i.e 4g13 and 6a13...ones a straight 4 1.3 and the other a v6 2.5.
4g12 and 6a12....straight 4 1.4 and v6 2.0

The 3rd digit in code XX1X is to indicate the engine family
4g1X orion series
4g3X Saturn
4g6X sirius
4g5X Astron
4g4X neptune
The fourth digit is not a guide to displacement or how its place within the family but just the model number.
XgXX the g here is to show its gasoline engine

XdXX the d is here to show its a diesel

XaXX is to show it has an aluminium head

However, these are not relevant to new mitsu engines since they use a new structure.i.e new lancer has a 4b10,4b11,4b12,colt uses 4a90,4a91

This is the print out list i got from my mechanic at the local mitsu dealer for when i was sourcing older model engines. It is actually correct.