The Very Basics - Mitsubshi Engine Naming
Mitsubishi Motors uses a simple four-digit naming scheme for its automobile engines:
- The first digit signifies the number of cylinders
- The second is the fuel type; "G" for gasoline, "R" for race fuel?, "D" for Diesel
- The third is the engine family
- The fourth is the engine model
- The first digit is sometimes omitted, shifting the entire scheme by one to make room for another character, such as "T" for turbocharged or "B"for second-generation.
Mitsubishi 4 Cylinder Engine Families
Mitsubishi has developed five families of straight-4 engines:
- 4G1x "Orion" - 1.2 L to 1.5 L
- 4G3x "Saturn" - 1.2 L to 1.8 L
- 4G5x "Astron" - 2.0 L to 2.6 L "Silent Shaft" <--- G54B
- 4G6x "Sirius" - 1.6 L to 2.4 L <--- 4G63
- 4G9x - 1.6 L to 2.0 L
- There is a future upcoming family of straight-4 engines in a joint-venture with DaimlerChrysler and Hyundai known as Global Engine Manufacturing Alliance (GEMA)
All of the above information was gathered using Wikipedia. I have gathered from it and several other sites, the full history of Mitsubishi Engines. This can be found on this thread from the ZeroG message boards.
The Sirius Family of Engines (4G6x)
One of the few beautiful reasons why I chose to swap this motor into my car was how modular this family of motors was. There are just so many factory configurations, let alone stock ones. Here is a short list:
- 4G61 - 1.6L (Summit, Colt Motor)
- 4G63 - 2.0L (Turbo, N/T, DOHC, SOHC, Wide, Narrow, 6bolt, 7bolt, Evo 4+, aka: G63B)
- 4G64 - 2.4L (N/T, SOHC, DOHC, Wide, Narrow, 6bolt, 7bolt, aka: 4GCS, G64B)
People have also mixed up some of these parts too!
- 2.3L "stroker" motor (2.0L Block, 2.4L crank, Custom Rods/Pistons)
- 2.1L "destroker" motor (2.4L Block, 2.0L crank, Custom Rods/Pistons)
I'm still waiting on a 15,000rpm 1.6L crank in a 2.4L block :-D
In this section I'm going to talk about what little I know about these different blocks and combos.
The 4G63 has been around since the early 1980s. It originally showed up in world market Starions and a few Lancer rally cars as the 2.0L SOHC 12 Valve "Sirius Dash" Engine (wideblock). More recently it has been released in legendary DSM's (Eclipse, Talon, Laser). The early first generation (1G 6 bolt) cars were produced from 1989 - 1993.5. These are regarded at some of the best ever. The later 7 bolt motors were also potent machines, but according to some, suffer from thrust bearing problems (aka Crankwalk).The engine comes from the factory rated at 195HP @ 6000 RPM while torque peaks at 203ft/lbs @ 3000 RPM. There is lots of aftermarket support for this motor and there are motors available everywhere. Some DSMs can do 450HP on the stock bottom end and well over 1000HP with upgraded internals and good workmanship.
The cars were not the only vehicles to have the 4G63 motors. The MightyMax/D50 trucks also came with the 2.0L 4G63 or G63B engines. Depending on the year and transmission, you could find either a wide or narrow block. There will be more on this in the Transmission Section. Because these trucks were RWD, they offer some intersting parts which us RWD 4G63 people can use such as: mounts, transmissions, flywheels, starters, etc. As with the other Sirius Engines, later models came with a 7 bolt flywheel.
The 2.4L 4G64 has been growing in popularity with the DSM crowd. They have been using this bottom end for a few years. Many have used the crank in 2.3L "stroker" motors. It comes in several varieties: narrow and wide bellhousings, 6 bolt and 7 bolt (1G and 2G), just as the 4G63 did. The really interesting thing is that its basically the same casting as the 4G63.. only with a 6mm higher deck height (12mm more stroke / 2), a larger bore (87mm) and longer stroke (12mm longer). It's not as square or revy as the 4G63, but the added spooling and low end makes up for that.
I think I skipped the most important thing. The 2.0 DOHC head bolts to the thing! And even more important to us RWD guys is that the wide 6 bolt version is available in U.S. D50 trucks. This, as you might have figured out means we can use the Starion flywheel, clutch, slave cylinder and transmission.
I know it uses the same rods as the 4G63s, has ~9.5:1 compression (yuck).
There are some differences however. Because all but the 1994 Galant DOHC were SOHC, main caps are not bridged like on the DOHC motors. There are also no "turbo" oil squirters in the block.
SOHC and DOHC
Sirius motors came with 2 main timing configurations. Dual Over Head Cam (DOHC) and Single Over Head Cam (SOHC). The DOHC head can be found on many different Sirius engines. There are some small differences, but for the most part all are compatible and can be swapped back and forth (even a 1.6L DOHC head onto a 2.4L Turbo). I have gathered info on the SOHC -> DOHC conversion in this section.
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