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Mazda B6T Specifications
| Engine Model: Mazda B6T |
| Engine Type: 4-cycle 4-cylinder 16-valve DOHC turbocharged liquid-cooled gasoline |
| Total Displacement: 97.5 cu.in (1.59 L) |
| Rated Engine Power: 150-165 Hp (110-121 kW) at 6000 rpm |
| Fuel System Type: Mazda EGI multi-point fuel injection |
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| General Technical Data |
The Mazda B6T is a turbocharged, intercooled, dual overhead camshaft (DOHC), 16-valve, inline-four-cylinder gasoline engine. It represents Mazda's high-performance "B-series" engine family from the late 1980s and early 1990s. Based on the naturally aspirated B6 (1.6L) block, the B6T was heavily fortified with reinforced internals and equipped with an IHI RHB5 VJ11 turbocharger, an air-to-air intercooler, and electronic fuel injection.
Designed for low-weight, high-power
applications, it was a key component in Mazda's foray into the "hot
hatch" and sport compact segment. It is renowned for its robust
engineering, significant tuning potential, and its role in iconic
vehicles like the 323 GTX and GT-R. The engine delivers strong mid-range
torque and a characterful power band, making it a favorite among
enthusiasts. Its design philosophy prioritized durability under boost,
setting it apart from many contemporary turbo engines.
Engine Family / Model: Mazda B-series, Model B6T.
Engine Type: Inline-four cylinder, transverse-mounted, four-stroke
cycle, water-cooled, turbocharged and intercooled gasoline engine.
Fuel Management: Electronic Fuel Injection (EFI), multi-point (port
injection).
Aspiration: Forced induction via turbocharger and air-to-air
intercooler.
Bore: 78.0 mm / 3.071 inches.
Stroke: 83.6 mm / 3.291 inches.
Displacement: 1,597 cc / 97.5 cubic inches.
Compression Ratio: 8.2 : 1.
Firing Order: 1-3-4-2.
Rotation Direction (from front/timing belt end): Clockwise.
Maximum Power Output (JIS Net): 110 kW (150 Hp) at 6,000 rpm (323 GTX).
Output varied by application; GT-R and Capri applications produced up to
121 kW (165 PS).
Maximum Torque: 190 Nm (140 lb-ft) at 3,000 rpm (GTX). Up to 206 Nm (152
lb-ft) in later/higher-output versions.
Recommended Fuel: Premium unleaded gasoline, 95 RON or higher.
Redline: 6,500 rpm (electronically limited). Fuel cut-off at 7,000 rpm.
Boost Pressure (Stock): 7.25-8.70 psi (0.51-0.61 bar / 51-61 kPa).
| Cylinder Block |
Construction: Cast iron, with deep skirt design for
rigidity. It is a strengthened version of the standard B6 block to
withstand increased cylinder pressures from turbocharging.
Cylinder Bores: Integral (parent bore) in the casting. Bore diameter is
78.00-78.03 mm (3.0709-3.0720 inches) for standard size.
Crankshaft: Forged steel crankshaft, supported by five main bearings.
Main journal diameter is 54 mm (2.126 inches). Crankpin (connecting rod
journal) diameter is 42 mm (1.654 inches).
Main Bearings: Steel-backed, aluminum alloy shell bearings.
Pistons: Forged aluminum alloy, with a dished crown to achieve the lower
compression ratio. Features three rings (two compression, one oil
control).
Connecting Rods: Forged steel, I-beam design. Rifle-drilled for piston
pin lubrication.
| Cylinder Head and Valve |
Construction: aluminum alloy, cross-flow design,
with integrated camshaft towers (no separate bearing caps).
Valve Arrangement: Dual Overhead Camshafts (DOHC), driven by a toothed
timing belt. Four valves per cylinder (16-valve total).
Valve Configuration: Intake and exhaust valves arranged in a pent-roof
combustion chamber.
Valve Seat Angle: 45 deg.
Valve Diameter: Intake: 30.5 mm (1.201 inches). Exhaust: 26.0 mm (1.024
inches). Slight variations may exist between models.
Valve Stem Diameter: Intake: 6.0 mm (0.236 inches). Exhaust: 6.0 mm
(0.236 inches).
Valve Clearance (Hydraulic Lash Adjusters): Utilizes hydraulic valve
lash adjusters (HLAs) within the rocker arms, making periodic mechanical
adjustment unnecessary. Valve clearance is maintained automatically via
engine oil pressure.
Camshaft Drive: Toothed rubber timing belt with automatic hydraulic
tensioner. Note: Belt change intervals are critical.
| Fuel System |
Injection System: Mazda EGI (Electronic Gasoline Injection) multi-point
port fuel injection.
Engine Control Unit (ECU): Mazda-specific digital ECU with a dedicated
map for boost control and ignition retard. Includes a knock sensor for
protection.
Fuel Injectors: High-impedance, top-feed injectors. Flow rate 320-330 cc
per minute at standard fuel pressure.
Fuel Pressure Regulator: Vacuum/boost referenced, mounted on the fuel
rail. Maintains a base pressure of 2.5 bar (36 psi) without
vacuum/boost.
Fuel Pump: High-pressure in-tank electric pump.
Throttle Body: Single-bore, cable-operated. Diameter 55 mm (2.17
inches).
Air Flow Meter: Vane-type (AFM) or, in later models, a more
sophisticated sensor. Measures intake air volume for ECU calculation.
Turbocharger: IHI RHB5 VJ11 water-cooled turbocharger with an integral
wastegate actuator.
Intercooler: Front-mounted air-to-air intercooler.
| Lubrication System |
Type: Full-pressure, forced feed system with a full-flow oil filter.
Includes oil cooling jets directed at the underside of the pistons for
additional cooling. Oil Pump: Gear-type, chain-driven from the
crankshaft, mounted at the front of the engine. Oil Filter: Spin-on
disposable canister type. Oil Cooler: Engine oil cooler is integrated
with the oil filter mount, using engine coolant for heat exchange.
Relief Valve: Located in the oil pump housing. Oil Capacity (including
filter): 3.7 liters (3.9 US quarts / 3.3 Imperial quarts). Recommended
Oil Grade: For normal operation: API SG or higher, SAE 10W-30 or 10W-40.
For severe/high-boost use or warmer climates: SAE 15W-50. Modern
equivalents: API SN/SP, with attention to high-temperature shear
stability. Operating Oil Pressure: At operating temperature: 294-441 kPa
(3.0-4.5 kgf/cm2 / 43-64 psi) at 3,000 rpm. Minimum idle pressure: 98
kPa (1.0 kgf/cm2 / 14 psi).
| Cooling System |
Type: Pressurized, forced circulation with a coolant-to-oil heat
exchanger (oil cooler) and a dedicated turbocharger coolant circuit.
Water Pump: Centrifugal, driven by the timing belt. Thermostat: Wax
pellet type. Opening temperature 82°C (180°F) or 88°C (190°F). Radiator
Pressure Cap: 88 kPa (0.9 kgf/cm2 / 13 psi).
Coolant Capacity (engine + radiator, approx.): 6.0 liters (6.3 US quarts
/ 5.3 Imperial quarts). Vehicle dependent, especially with intercooler
plumbing. Coolant Recommendation: Ethylene-glycol based antifreeze mixed
with demineralized water, 50/50 ratio. Turbocharger Cooling: The
turbocharger center housing is plumbed into the engine's main coolant
circuit for post-shutdown heat soak protection.
| Other Systems |
Electrical System: 12-volt direct current, negative ground.
Ignition System: Distributorless Ignition System (DIS) with a
waste-spark coil pack. Timing is fully controlled by the ECU.
Spark Plugs: NGK BCPR6E-11 or equivalent (copper core). Gap: 1.0-1.1 mm
(0.039-0.043 inches).
Boost Control: Integral wastegate actuator on turbocharger. ECU may
utilize a solenoid for slight boost control variation.
Emission Controls: Exhaust Gas Recirculation (EGR), catalytic converter,
and evaporative emission system (EVAP).
| Dimensions and Weight |
Length (from front of timing cover to rear of block): 600 mm (23.6
inches).
Width (over valve cover): 650 mm (25.6 inches).
Height (from oil pan sump to top of valve cover): 650 mm (25.6 inches).
Dry Weight (engine only, long block): 135 kg (298 lbs).
| Maintenance Data |
Engine Oil and Filter Change Interval: Under normal service: 5,000 km
(3,100 miles) or 6 months. Severe (frequent boost, short trips): 3,000
km (1,860 miles) or 3-4 months. Spark Plugs: Replace every 20,000-30,000
km (12,400-18,600 miles). Tuning or high-boost use requires more
frequent changes and a cooler heat range. Timing Belt: CRITICAL. Replace
every 60,000 km (37,300 miles) or 5 years, whichever comes first.
Includes replacement of tensioner and idler pulleys. Coolant
Replacement: Every 2 years or 40,000 km (24,850 miles). Air Filter:
Inspect/replace every 20,000-30,000 km (12,400-18,600 miles). More
frequently in dusty conditions. Fuel Filter: Replace every 40,000 km
(24,850 miles).
Valve Clearance: Hydraulic (HLAs). No scheduled adjustment. Noisy HLAs
may require cleaning or replacement. Accessory Drive Belts: Inspect
tension and condition every oil change. Replace as needed.
| Tightening Torques |
Cylinder Head Bolts (M11): Use a three-step torque-angle procedure. Step
1: 39-44 Nm (29-32 lb-ft). Step 2: Tighten an additional 90 deg (1/4
turn). Step 3: Tighten a final 90 deg (1/4 turn). Always follow the
specific workshop manual sequence.
Main Bearing Cap Bolts: 54-61 Nm (40-45 lb-ft).
Connecting Rod Cap Bolts: 36-40 Nm (27-30 lb-ft). Replace with new bolts
during reassembly.
Flywheel to Crankshaft Bolts: 88-98 Nm (65-72 lb-ft).
Crankshaft Pulley Bolt: 108-118 Nm (80-87 lb-ft).
Camshaft Sprocket Bolts: 39-44 Nm (29-32 lb-ft).
Spark Plugs: 18-22 Nm (13-16 lb-ft).
Oil Pan (Sump) Bolts: 7.8-11.8 Nm (5.8-8.7 lb-ft).
Valve Cover Bolts: 3.9-5.9 Nm (2.9-4.3 lb-ft).
Intake Manifold Nuts/Studs: 19-24 Nm (14-18 lb-ft).
Exhaust Manifold/Turbo Nuts: 39-49 Nm (29-36 lb-ft).
Oil Filter: Hand-tighten plus 2/3 to 3/4 turn after gasket contacts
base.
| Vehicle Applications |
The Mazda B6T engine was installed in several high-performance,
limited-production Mazda models from the late 1980s to early 1990s:
Mazda 323 / Familia (BF Series): Primarily in the all-wheel-drive 323
GTX (1988-1989) and the even more potent, homologation-special 323 GT-R
(1991-1992). The GT-R featured a slightly higher-output variant (165
PS). Mazda MX-6 / 626 (GC Series): Used in the Japanese-market "MX-6 GT"
/ "626 GT" turbo models (1988-1991).
Similar output to the 323 GTX. Ford Capri (Australia): The
Australian-market Ford Capri (1991-1994) used a transverse-mounted B6T
as its sole engine option, detuned slightly for emissions but retaining
the core architecture. Mazda Familia GT-Ae (BF Series): Japanese-market
Familia with electronically controlled active 4WD and the B6T. Mazda AW
chassis (Japan): Used in some limited JDM models.
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