Mitsubishi 6A12 Mivec Specifications
| Engine Model: Mitsubishi 6A12 Mivec |
| Engine Type: 4-cycle 6-cylinder V-block DOHC 24-valve liquid-cooled gasoline |
| Total Displacement: 121.9 cu.in (1.99 L) |
| Rated Engine Power: 200 Hp (147 kW) at 7500 rpm |
| Fuel System Type: Multi-point fuel injection |
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The Mitsubishi 6A12 MIVEC is a 2.0-liter V6 gasoline
engine produced during the 1990s as a performance-oriented variant of the 6A
series engine family. It represented a significant achievement in naturally
aspirated engine design, delivering high specific output through advanced
valvetrain technology and a high-rpm operating range. The engine incorporates
Mitsubishi’s MIVEC (Mitsubishi Innovative Valve timing and lift Electronic
Control) system, a dual-profile camshaft arrangement that switches between
low-speed and high-speed cam lobes to optimize volumetric efficiency across the
entire rev range.
The 6A12 MIVEC is a 60-degree V6 with a dual overhead camshaft (DOHC)
configuration and 24 valves. Its architecture emphasizes high-rpm power
delivery, with a relatively short stroke of 69.0 mm (2.72 in) that permits
piston speeds exceeding 20 m/s at the engine’s 8,200 rpm redline. The MIVEC
system engages high-lift, long-duration cam profiles above 5,500 rpm, allowing
the engine to produce peak power at 7,500 rpm while maintaining drivability at
lower engine speeds. The engine was primarily installed in Japanese Domestic
Market (JDM) performance models, including the Mitsubishi FTO GPX, Galant VR-M,
and related top-spec variants.
The 6A12 MIVEC is a water-cooled, four-stroke, naturally aspirated V6 gasoline
engine configured for transverse mounting in front-wheel-drive vehicle
architectures. Its design prioritizes high-rpm power output and responsive
throttle characteristics.
Engine Type: 60-degree V6, 4-cycle, water-cooled, naturally aspirated.
Displacement: 1,998 cc (121.9 cu.in).
Bore and Stroke: 78.4 mm (3.09 in) x 69.0 mm (2.72 in).
Compression Ratio: 10.0:1.
Valvetrain: DOHC, 24-valve with belt drive and MIVEC variable valve timing and
lift.
Fuel System: ECI-MULTI (electronic control injection, multi-point).
Firing Order: 1-2-3-4-5-6.
Maximum Power: 147 kW (200 Hp) at 7,500 rpm.
Maximum Torque: 200 Nm (148 lb-ft) at 6,000 rpm.
Idle Speed: 750 ± 50 rpm.
Engine Redline: 8,200 rpm (fuel cut).
The cylinder block is constructed from cast iron, a
material selected for its rigidity and vibration-damping properties, which are
particularly important in a high-rpm V6 configuration. The 60-degree V-angle is
chosen to provide inherent primary and secondary balance, reducing the need for
balance shafts while maintaining a compact overall width suitable for transverse
mounting. The block incorporates a closed-deck design at the upper cylinder
region, providing robust support for the cylinder head gaskets under the high
cylinder pressures generated at elevated engine speeds.
Cast-in-place cylinder bores are machined directly into the iron casting. The
block incorporates four main bearing webs with two-bolt main bearing caps per
cylinder bank, with the crankshaft supported by four main bearings. The
crankshaft is constructed from forged steel to withstand the stresses associated
with the 8,200 rpm redline. A stamped steel oil pan is sealed to the lower
crankcase, providing the oil reservoir. The block features water passages
designed to ensure uniform cooling across both cylinder banks.
Block Material: Cast iron
Bore Diameter (finished): 78.4 mm (3.09 in)
Main Bearing Caps: Cast iron, two-bolt design
Cylinder Bore Deformation Limit: 0.05 mm (0.0020 in)
The cylinder heads are manufactured from aluminum
alloy, with separate heads for each cylinder bank. The DOHC valvetrain actuates
24 valves - four valves per cylinder - through a system of roller rocker arms
and solid lifters (shim-over-bucket). The MIVEC system is integrated into the
cylinder head design, with each cylinder bank featuring two distinct cam
profiles per intake valve: a low-speed profile with reduced lift and duration
for low- to mid-range torque and fuel efficiency, and a high-speed profile with
increased lift and duration for maximum power output.
The camshafts are driven by a reinforced rubber timing belt from the crankshaft.
The MIVEC system uses oil pressure-actuated locking pins to switch the intake
camshaft followers between the low-speed and high-speed lobes. Switchover occurs
at approximately 5,500 rpm under wide-open throttle conditions, though the
engagement point varies with engine load and coolant temperature. The exhaust
camshafts operate on a fixed profile. Solid lifters with shims require periodic
manual valve clearance adjustment to maintain precise valvetrain control at high
engine speeds.
Head Material: Aluminum alloy.
Valve Configuration: DOHC, 4 valves per cylinder with roller rocker arms
and solid lifters.
Valve Diameter (Intake): 33.0 mm (1.30 in).
Valve Diameter (Exhaust): 28.0 mm (1.10 in).
Valve Stem Diameter: 5.5 mm (0.22 in).
Valve Seat Angle: 45 degrees.
MIVEC Switchover RPM: 5,500 rpm (standard calibration).
The 6A12 MIVEC employs an ECI-MULTI (electronic control
injection, multi-point) fuel system. This system uses six fuel injectors mounted
in the intake manifold, positioned to spray fuel directly onto the back of each
intake valve. The port injection design provides excellent air-fuel mixture
preparation and throttle response, with the injector location allowing fuel to
cool the intake valves during operation.
A fuel pump assembly located within the fuel tank supplies pressurized fuel to a
fuel rail that distributes fuel evenly to all six injectors. The engine control
unit (ECU) calculates injection pulse width based on input from the mass airflow
sensor, throttle position sensor, coolant temperature sensor, crankshaft
position sensor, and oxygen sensor feedback. The ECU is calibrated with specific
fuel and ignition maps for the MIVEC valvetrain, with fuel enrichment programmed
to correspond with cam profile switchover to maintain proper air-fuel ratios
under high-load conditions. Premium-grade fuel with a Research Octane Number of
96 or higher is recommended to realize the engine’s full power output.
Injection Type: Multi-point electronic fuel injection (ECI-MULTI)
Fuel Pressure: 255-294 kPa (37.0-42.6 psi) with vacuum line disconnected
Fuel Injector Resistance: 12.0-16.0 Ohms
Fuel Requirement: 96 Research Octane Number (RON) or higher (premium)
Fuel Cutoff: 8,200 rpm
The lubrication system is a fully pressurized, wet-sump
design utilizing a gear-type oil pump mounted to the front of the crankshaft.
The oil pump draws lubricant from the stamped steel oil pan through a mesh
strainer and circulates it through a full-flow, replaceable oil filter before
entering the main oil gallery. From the gallery, pressurized oil is distributed
to the crankshaft main bearings, connecting rod bearings, camshaft bearings,
rocker arm assemblies, MIVEC control valves, and timing belt tensioner.
A pressure relief valve integrated into the oil pump maintains system pressure
within operational limits to prevent over-pressurization during cold starts. The
lubrication system is designed to provide adequate protection under the
sustained high-rpm operation characteristic of the MIVEC engine’s intended use.
The MIVEC system requires sufficient oil pressure to actuate the switching
mechanism; low oil level or pressure can prevent proper cam profile engagement.
Oil Type: SAE 5W-40, 10W-40, or 15W-50 (API SG, SH, or higher)
Oil Capacity (with filter): 4.2 liters (4.4 US qt)
Oil Pressure (at 3,000 rpm): 294-392 kPa (42.6-56.9 psi)
Oil Pump Type: Gear-type, crankshaft-driven
Oil Filter Type: Spin-on, full-flow
The cooling system is a pressurized, liquid-cooled
design employing a cross-flow aluminum radiator with an electric cooling fan. A
centrifugal-type water pump, driven by the timing belt, circulates coolant
through the engine block, cylinder heads, heater core, and throttle body warmer.
A wax-pellet thermostat regulates coolant flow to maintain optimal operating
temperature, with a bypass circuit that allows the engine to warm rapidly by
circulating coolant only within the engine until the thermostat opens.
The system is designed to provide uniform cooling across both cylinder banks and
the aluminum cylinder heads. The thermostat is calibrated to maintain lower
operating temperatures suited to the engine’s high-rpm design, ensuring
consistent thermal management during sustained high-load operation.
Coolant Type: Ethylene-glycol based antifreeze with corrosion inhibitors
Coolant Capacity: 6.5-7.0 liters (6.9-7.4 US qt)
Thermostat Opening Temperature: 76-80 °C (169-176 °F)
Thermostat Full-Open Temperature: 90 °C (194 °F)
Radiator Cap Pressure: 88-108 kPa (12.8-15.7 psi)
Water Pump Type: Centrifugal, timing belt-driven
| Intake and Exhaust Systems |
Intake System: Aluminum intake manifold with tuned
runners of equal length. The manifold incorporates a resonance chamber designed
to enhance intake wave tuning for the engine’s high-rpm operating range. A
throttle body with a mechanically operated butterfly valve controls airflow into
the engine. The intake system incorporates an air cleaner housing with a
dry-type paper filter element.
Exhaust System: Stainless steel exhaust manifolds with individual runners per
cylinder bank. The exhaust system incorporates a heated oxygen sensor upstream
of the catalytic converter for fuel trim feedback. The system is tuned to
complement the engine’s high-rpm power delivery.
Distributor-based ignition system with a
camshaft-driven distributor on earlier variants. Later variants employ a
distributorless ignition with individual coil packs or a waste-spark system. The
system incorporates a crankshaft position sensor and camshaft position sensors
for precise ignition timing control. Ignition timing maps are optimized for the
MIVEC cam profiles, with timing advanced under high-lift operation to maximize
power output.
MIVEC System: The MIVEC system utilizes separate
low-speed and high-speed cam lobes for the intake valves. Low-speed lobes
provide reduced lift and duration for stable idle, low emissions, and torque.
High-speed lobes provide increased lift and duration for maximum volumetric
efficiency at high engine speeds. Switchover is controlled by the ECU based on
engine speed, throttle position, and coolant temperature, using oil pressure to
actuate locking pins that connect the low-speed follower to the high-speed lobe.
The system provides a noticeable change in engine character at switchover.
Timing Drive: A reinforced rubber timing belt with integral teeth drives the
camshafts from the crankshaft sprocket. The belt also drives the water pump. An
automatic spring-loaded tensioner maintains belt tension. The timing belt is a
scheduled maintenance item with a defined replacement interval. The engine is of
interference design; timing belt failure results in valve-to-piston contact.
Overall Length: 610 mm (24.0 in)
Overall Width: 720 mm (28.3 in)
Overall Height: 680 mm (26.8 in)
Dry Weight (complete engine): 134 kg (295 lb)
Oil Change Interval: 5,000 km (3,000 mi) under normal
driving conditions; 3,000 km (1,800 mi) under severe conditions. Oil Filter
Change: At every oil change. Timing Belt Replacement: 80,000 km (50,000 mi) or 4
years. Engine Coolant Replacement: 40,000 km (25,000 mi) or 2 years.
Spark Plug Replacement: 20,000 km (12,500 mi) for standard plugs; 40,000 km
(25,000 mi) for platinum plugs. Spark Plug Type: NGK PFR6J-11 or equivalent
(platinum-tipped). Spark Plug Gap: 1.0-1.1 mm (0.039-0.043 in).
Drive Belt (Accessory) Inspection: Every 10,000 km (6,000 mi) for tension,
cracking, and glazing. Air Filter Replacement: 20,000 km (12,500 mi) or as
indicated by inspection. Fuel Filter Replacement: 40,000 km (25,000 mi) for
external filter types.
Valve Clearance Adjustment: Inspect and adjust every 40,000 km (25,000 mi).
Intake: 0.10-0.14 mm (0.0039-0.0055 in) cold. Exhaust: 0.20-0.24 mm
(0.0079-0.0094 in) cold. Shim replacement is required for adjustment. Idle Speed
Adjustment: 750 ± 50 rpm with no electrical or accessory load.
Cylinder Head Bolts (M10 x 1.25), 1st pass: 20-25 Nm
(15-18 lb-ft).
Cylinder Head Bolts (M10 x 1.25), 2nd pass: 50-55 Nm (37-41 lb-ft).
Main Bearing Cap Bolts (M10 x 1.25): 45-50 Nm (33-37 lb-ft).
Connecting Rod Cap Bolts (M8 x 1.0): 25-28 Nm (18-21 lb-ft).
Camshaft Bearing Cap Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Intake Manifold Bolts (M8 x 1.25): 16-20 Nm (12-15 lb-ft).
Exhaust Manifold Nuts (M8 x 1.25): 16-20 Nm (12-15 lb-ft).
Spark Plugs: 18-22 Nm (13-16 lb-ft).
Oil Pan Bolts (M6 x 1.0): 8-10 Nm (71-89 lb-in).
Water Pump Bolts (M6 x 1.0): 8-10 Nm (71-89 lb-in).
Timing Belt Tensioner Bolt (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Crankshaft Pulley Bolt (M14 x 1.5): 130-140 Nm (96-103 lb-ft).
Flywheel / Drive Plate Bolts (M10 x 1.25): 70-75 Nm (52-55 lb-ft).
The Mitsubishi 6A12 MIVEC engine was utilized across a
range of Japanese Domestic Market performance models, positioned as the flagship
naturally aspirated engine in the respective vehicle lineups.
Mitsubishi FTO (DE3A): GPX and GP Version R trims (1994-2000).
Mitsubishi Galant (EA1A, EA5A): VR-M trim (1992-1996).
Mitsubishi Emeraude (E54A): Top-spec variants with MIVEC engine.
Mitsubishi Eterna (E54A): Top-spec variants with MIVEC engine.
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