1g Astron II

From Mitsipedia
Astron II (First Generation)
1g efi engine.jpg
Astron II in a first generation Magna
Manufacturer Mitsubishi Motors Australia Limited
Also called 4G54
Production 1985 - 1996
Configuration In-line 4
Displacement 2555cc
Cylinder block alloy Cast Iron
Cylinder head alloy Aluminum Alloy
Valvetrain SOHC
Predecessor Astron
Successor Astron II (Second Generation

The first generation Astron II was an improved version of the original Astron which debuted in the late 1970s. The first Astron was revolutionary as it was the first engine to use balance shafts to make the engine feel much smoother.

The Astron II was only available in 2.6 litre form. The 2.6 litre engine was praised for being powerful, economical and refined.

The engine was fitted to all first generation Magnas and carby second generation models. Second generation Magnas fitted with EFI used a revised version of the engine.

Technical Specifications

Type In line 4 cylinder overhead cam with counter balance shafts. Transversely mounted
Displacement 2555cc (2.6 litres)
Bore 91.1mm
Stroke 98mm
Maximum oversize 1.00mm
Compression Ratio 8.8:1
Firing Order 1,3,4,2
Power output (Carby) 83 kW @ 5200 rpm, 200Nm @ 2400 rpm
Power Output (EFI) 93 kW @ 4800 rpm, 205 Nm @ 2400 rpm
Type Alluminum Alloy with hemispherical combustion chambers and crossflow design
Inlet Valve Diameter 46.00mm
Exhaust Valve Diameter 38.00mm
Valve Face Angle 45 º
Valve Clearance Maintained by hydraulic lash adjusters
Inlet Opens 25º BTDC
Inlet Closes 59º ABDC
Inlet Duration 264º
Exhaust Opens 64º BBDC
Exhaust Closes 20º ATDC
Exhaust Duration 264º
Overlap 45º
Inlet Cam Lobe Height 42.50mm
Exhaust Cam Lobe Height 42.56mm
Nominal Cam Lift 10.50mm
3 cylinder
3A9x 3A90 3A91 3A92
4 cylinder
Neptune 4G41 4G42
Orion 4G11 4G12 4G13 4G15 4G17 4G18 4G19 G4ED
Sirius 4G61 4G62 4G63 4G64 4G67 4G69
Astron 4G51 4G52 4G53 4G54
Astron II Original Revised
Saturn 4G30 4G31 4G32 4G33 4G37
4G9x 4G91 4G92 4G93 4G94
4A9x 4A90 4A91 4A92
4B1x 4B10 4B11 4B11T 4B12
Inline 6
Saturn 6 6G34
6G7x 6G71 6G72 SOHC 12v 6G72 SOHC 24v 6G72 DOHC Early 6G74 Late 6G74 Ralliart 6G74 6G75
6A1x 6A10 6A11 6A12 6A13
6B3x 6B31
8A80 8A80