Mitsubishi 4B12

Mitsubishi 4B12The Mitsubishi 4B12 is an inline 2.4 liter (2,359 cc, 143.9 cu in) four-cylinder, four-stroke cycle gasoline engine manufactured by Mitsubishi Motors since 2007.

The Mitsubishi 4B12 engine has an aluminum block and cylinder head, pentroof type combustion chamber, dual overhead camshaft (DOHC), four-valve designs with valve timing electronic control system (MIVEC) on both camshafts (from 2011 for intake side only), electronic spark-advance control type ignition system, and electronic control multi-point fuel injection system.

An 88.0 mm (3.46 in) cylinder bore and 97.0 mm (3.82 in) piston stroke give the engine a total of 2.4 L of displacement. The compression ratio rating is 10.5:1.

The Mitsubishi 4B12 produced 170 PS (125 kW; 167.6 HP) at 6,000 rpm of horsepower and from 226 N·m (23 kg·m, 166.6 ft·lb) at 4,100 rpm to 232 N·m (23.7 kg·m, 171 ft·lb) at 4,100 rpm of peak torque.

General information

Engine Specifications
Engine code 4B12
Layout Four stroke, Inline-4 (Straight-4)
Fuel type Gasoline
Production 2007-
Displacement 2.4 L, 2,359 cc (143.9 cu in)
Fuel system Electronic control MPI
Power adder None
Power output 170 PS (125 kW; 167.6 HP) at 6,000 rpm
Torque output From 226 N·m (23 kg·m, 166.6 ft·lb) at 4,100 rpm
to 232 N·m (23.7 kg·m, 171 ft·lb) at 4,100 rpm
Firing order 1-3-4-2
Dimensions (L x H x W):

Cylinder block

The 4B12 has an aluminum block, cylinder bore is 88.0 mm (3.46 in) and the piston stroke is 97.0 mm (3.82 in), the compression ratio is 10.5:1.

The pistons are each fitted with two compression rings and a single oil ring, connecting rods are 143.75 mm (5.659 in) center-to-center long. The pistons are made of a special aluminum alloy. The connecting rods are made of highly rigid, forged carbon steel.

Cylinder block
Cylinder block alloy Aluminium
Compression ratio: 10.5:1
Cylinder bore: 88.0 mm (3.46 in)
Piston stroke: 97.0 mm (3.82 in)
Number of piston rings (compression / oil): 2/1
Number of main bearings: 5
Block Height:
Cylinder inner diameter (standard): 86.000 mm (3.3858 in)
Piston skirt diameter (standard):
Piston ring side clearance: Top 0.030-0.070 mm (0.0012-0.0028 in)
Second 0.030-0.070 mm (0.0012-0.0028 in))
Piston ring end gap: Top 0.150-0.250 mm (0.0059-0.0098 in)
Second 0.250-0.400 mm (0.0098-0.0157 in)
Oil 0.100-0.350 mm (0.0039-0.0138 in)
Connecting rod center distance: 143.75 mm (5.6594 in)
Crankshaft main journal diameter: 56.000 mm (2.2047 in)
Crankpin diameter: 48.000 mm (1.8898 in)

Cylinder head

The engine has an aluminum cylinder head with two chain-driven overhead camshafts and MIVEC (MITSUBISHI INNOVATIVE VALVE TIMING ELECTRONIC CONTROL SYSTEM) for both the intake and exhaust valves (since 2011 for the intake side only). Intake valves are 35.0 mm (1.38 in) in diameter, and the exhaust valves are 29.0 mm (1.14 in).

The MMC 4B12 engine does not have hydraulic lifters, so special valve tappets are used to adjust the valve clearance.

Cylinder head
Cylinder head alloy Aluminum
Cylinder head height:
Valve Arrangement: DOHC, chain drive
Valves: 16 (4 valves per cylinder)
Intake/Exhaust duration:
Valve head diameter: INTAKE 35.00 mm (1.378 in)
EXHAUST 29.0 mm (1.1417 in)
Valve length: INTAKE 113.180 mm (4.4559 in)
EXHAUST 105.887 mm (4.1688 in)
Valve stem diameter: INTAKE 5.500 mm (0.2165 in)
EXHAUST 5.500 mm (0.2165 in)
Cam height: INTAKE 44.1 mm (1.7362 in)
EXHAUST 45.0 mm (1.7717 in)

Maintenance data

Compression pressure
Standard value 1,440 kPa (209 psi) at 200 rpm
Minimum 1,000 kPa (145 psi) at 200 rpm
Differences of the cylinders (limit) 98 kPa (14 psi) at 200 rpm
Valve clearance
Intake valve 0.17-0.23 mm (0.0067-0.0091 in)
Exhaust valve 0.27-0.33 mm (0.0106-0.013 in)
Oil system
Recommended engine oil SAE 0W-20
Oil type API API: SM or higher
Engine oil capacity (Refill capacity) 4.9 L (5.18 US. qt, 4.31 Imp. qt.)
Ignition system
Spark plug NGK DIFR5C11
Spark plug gap 1.0-1.1 mm (0.0394-0.0433 in)

Vehicle applications

Model Years Produced
Mitsubishi Delica 2007-
Mitsubishi Lancer 2008-
Citroën C-Crosser 2008-
Peugeot 4007 2008-
Mitsubishi Lancer Sportback GTS 2009-
Mitsubishi Lancer GTS 2009-
Mitsubishi Outlander 2009-
Mitsubishi Galant 2010-
Mitsubishi Lancer SE AWC 2012-
Mitsubishi Lancer GT Manual 2013-
Mitsubishi Lancer 2015-
Mitsubishi RVR 2018-
Mitsubishi Outlander 2020-
Mitsubishi Eclipse Cross PHEV 2020-
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