Nissan RB25DET Specifications
| Engine Model: Nissan RB25DET |
| Engine Type: 4-cycle 6-cylinder DOHC 24-valve turbocharged liquid-cooled gasoline |
| Total Displacement: 152.5 cu.in (2.49 L) |
| Rated Engine Power: 245-260 Hp (181-193 kW) at 6400 rpm |
| Fuel System Type: Multi-point electronic fuel injection |
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The Nissan RB25DET engine is a 2.5-liter,
inline-six, turbocharged, water-cooled gasoline engine belonging to
Nissan’s renowned RB-series. It was introduced in the early 1990s and
gained popularity for its blend of durability, tuning potential, smooth
inline-six operation, and robust factory architecture.
Used primarily in the Nissan Skyline R33 and R34 models, as well as the
Stagea and Laurel in select markets, the RB25DET represents the
turbocharged evolution of the RB25DE, adding forced induction, stronger
internals, revised pistons, oil cooling improvements, turbo-specific cam
profiles, and electronically managed boost control. The engine is widely
respected in the enthusiast community for its ability to withstand
significant increases in Hp with basic supporting modifications.
The RB25DET is considered a mid-displacement performance engine within
the RB family, sitting between the smaller RB20DET and the legendary
RB26DETT. It offers a torque-rich driving experience, improved throttle
response over earlier RB engines, and a smooth, linear powerband that
makes it suitable for both street and motorsport use.
The cast-iron block provides extreme strength, while the aluminum DOHC
head optimizes breathing and high-rpm operation. Even in stock form, the
RB25DET remains a capable and durable performance platform.
The RB25DET has a displacement of 2,498 cc (152.5 cu in). Bore is
approx. 86.0 mm (3.39 inches). Stroke is approx. 71.7 mm (2.82 inches).
The compression ratio ranges 8.5:1 - 9.0:1 depending on series (Series
1, Series 2, NEO).
Factory power output varies by generation:
- Series 1: 245-250 hp at 6,400 rpm
- Series 2: 250-260 hp at 6,400 rpm
- NEO: 260-280 hp at 6,800 rpm
Torque output is approx. 220-255 lb-ft (approx. 298-345 Nm) at approx.
4,800 rpm. Idle speed is approx. 700-750 rpm. The firing order is
1-5-3-6-2-4. Redline varies but is 7,000-7,500 rpm depending on factory
ECU and variant.
The RB25DET uses a cast-iron block designed for high durability.
It features:
- Forged-steel crankshaft with seven main bearings
- Forged connecting rods
- Reinforced aluminum pistons with stronger ring lands
- Full-floating wrist pins
- Robust cooling and oil passages
The bottom end is known for handling increased boost and power when
tuned properly. Many builders push the stock bottom end well beyond
factory output with upgraded fueling and turbo systems.
The engine uses an aluminum DOHC cylinder
head with:
- Dual overhead camshafts
- Four valves per cylinder
- Timing belt-driven valvetrain
- Hydraulic lash adjusters
- NVCS (Nissan Variable Cam System) on some versions
- High-flow intake and exhaust ports
Cam profiles differ between generations, with NEO versions offering
improved airflow and revised valve geometry for better emissions and
torque.
The RB25DET uses a multi-point electronic fuel injection (MPFI) system.
Fuel system components:
- Electric in-tank fuel pump
- High-pressure fuel rail
- Multi-hole injectors (approx. 370-440 cc depending on version)
- Mass-airflow (MAF) sensor
- Throttle body
- ECU with boost, knock, and fuel mapping control
Fuel pressure ranges approx. 36-43 psi.
The ECU uses:
- O2 sensor
- Coolant-temperature sensor
- Throttle-position sensor
- Knock sensor
- Crank-angle sensor
- Cam-angle sensor
- Intake-air-temperature sensor
The lubrication system is a wet-sump, full-pressure design.
Specifications:
- Oil capacity 4.2-4.6 liters (approx. 4.4-4.9 US qt)
- Operating oil pressure approx. 45-65 psi at 3,000 rpm; approx. 15-20
psi idle
- Recommended oil viscosities: 5W-30, 10W-30, 10W-40 synthetic
The oil pump is crank-driven. Turbocharger lubrication is integrated
into the oil system. The RB25DET relies heavily on proper oil quality to
maintain turbocharger and valvetrain durability.
The engine uses a liquid-cooled, forced-circulation system.
Components:
- Aluminum radiator
- Belt-driven water pump
- Thermostat
- Electric fans
- Coolant passages in block and head
- Coolant expansion tank
Specifications:
- Thermostat begins opening approx. 82°C (180°F)
- Fully open approx. 95°C (203°F)
- Cooling capacity 7.0-8.0 liters (approx. 7.4-8.4 US qt)
| Intake and Exhaust Systems |
Induction System:
- Air cleaner assembly
- Intake snorkel
- MAF sensor
- Turbo inlet piping
- Intercooler assembly
- Throttle body
- Intake manifold with tuned long runners
Exhaust System:
- Turbo manifold (cast iron)
- Turbocharger
- Downpipe
- Catalytic converter
- O2 sensor
- Resonators and muffler
The RB25DET uses an electronically controlled ignition system.
Components:
- Coil-on-plug ignition
- Crank-angle sensor
- Cam-angle sensor
- Knock sensor
- High-energy ignition coils
Spark-plug gap is approx. 0.8-1.1 mm (0.032-0.043 inches). ECU timing
control prevents detonation under boost.
The RB25DET uses a turbocharger tailored for balanced performance.
The factory turbos:
- Series 1: ceramic turbine wheel
- Series 2: improved ceramic turbine
- NEO: steel turbine for increased durability
Boost pressure ranges 7-10 psi depending on variant.
The system includes:
- Turbocharger
- Wastegate
- Front-mount or side-mount intercooler
- Boost-control solenoid
- Charge-air pipes
Ceramic turbines offer fast spool but are more fragile at high boost.
- Length 780-830 mm (30.7-32.7 inches)
- Width 630-650 mm (24.8-25.6 inches)
- Height 690-720 mm (27.2-28.3 inches)
Dry weight 180-200 kg (397-440 lb).
- Oil and filter every 5,000-8,000 km
- Air filter every 20,000 km
- Spark plugs every 20,000-40,000 km
- Coolant every 2 years
- Fuel filter every 30,000-40,000 km
- Timing belt every 100,000 km (60,000 miles)
Compression pressure:
- Approx. 150-185 psi
- Variation < 10 percent
- Cylinder-head bolts: approx. 85-95 lb-ft (115-130 Nm)
- Main-bearing caps: approx. 60-70 lb-ft (81-95 Nm)
- Rod bolts: approx. 28-35 lb-ft (38-48 Nm)
- Flywheel bolts: approx. 75-85 lb-ft (102-115 Nm)
- Intake-manifold bolts: approx. 18-22 lb-ft (24-30 Nm)
- Exhaust-manifold nuts: approx. 25-30 lb-ft (34-40 Nm)
- Spark plugs: approx. 15-20 lb-ft (20-27 Nm)
- Drain plug: approx. 25-30 lb-ft (34-40 Nm)
- Nissan Skyline R33 GTS-25T
- Nissan Skyline R34 GT-T
- Nissan Stagea WC34
- Nissan Laurel C34/C35 (turbo trims)
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