Nissan RB25DE NEO Specifications
| Engine Model: Nissan RB25DE NEO |
| Engine Type: 4-cycle inline 6-cylinder DOHC 24-valve liquid-cooled gasoline |
| Total Displacement: 152.5 cu.in (2.49 L) |
| Rated Engine Power: 197-200 Hp (146-148 kW) at 6400 rpm |
| Fuel System Type: Multi-point electronic fuel injection |
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The Nissan RB25DE NEO engine is a 2.5-liter,
inline-six, naturally aspirated gasoline engine developed as the
advanced evolution of the RB25DE. Released primarily for the Nissan
Skyline R34 and other high-end rear wheel drive sedan platforms, the
RB25DE NEO represented the final refinement of Nissan’s naturally
aspirated RB lineup before the RB-series was discontinued.
The “NEO” designation signified a major engineering upgrade focused on
emissions improvement, torque enhancement, fuel efficiency optimization,
and improved high rpm stability without sacrificing the smoothness
characteristic of Nissan’s inline six engines.
Compared to earlier RB25DE versions, the NEO engine introduced upgraded
intake port geometry, revised combustion chambers, higher compression,
lighter valvetrain components, redesigned pistons, improved cooling
passage locations, coil on plug ignition, and new generation NVCS
(Nissan Variable Cam System). These improvements enhanced torque output,
broadened the usable powerband, and significantly reduced fuel
consumption and exhaust emissions.
The RB25DE NEO, though often overshadowed by its turbocharged sibling
RB25DET NEO, remains extremely respected for its reliability, smooth
operation, linear power delivery, and strong base architecture. It is
favored in restoration projects, JDM swaps, and motorsport categories
where turbocharging is restricted.
The RB25DE NEO 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 engine uses an oversquare configuration ideal for high rpm
breathing. Compression ratio is approx. 10.5:1 - 11.0:1 depending on
model variant, higher than earlier RB25DE units due to combustion
chamber efficiency improvements.
Power output is 197-200 hp at 6,400 rpm. Torque output is 188-195 lb-ft
(255-265 Nm) at 4,800 rpm. The firing order is 1-5-3-6-2-4. Idle speed
is approx. 700-750 rpm. Redline is 7,200 rpm depending on ECU
calibration. The engine features smooth, naturally aspirated power
delivery across the rpm range.
The RB25DE NEO retains the robust cast-iron block with deep skirts.
Key bottom end details include:
- Forged steel crankshaft with seven main bearings
- Forged connecting rods
- Aluminum pistons with low friction skirt coatings
- Full floating wrist pins
- Reinforced ring lands for high compression operation
- Optimized oil galleries for improved lubrication under high rpm
The bottom end is designed for stability, long life, and high rpm
operation. Oil flow was refined compared to earlier RB25DE
configurations to reduce valvetrain starvation during extended highspeed
driving.
The RB25DE NEO uses a significantly upgraded aluminum DOHC cylinder
head.
Enhancements include:
- Completely redesigned intake and exhaust ports
- Revised combustion chamber for high swirl, efficient burn
- Lighter valves
- Stiffer valve springs
- Roller rocker type cam followers
- NVCS (Nissan Variable Cam System) on the intake camshaft
- Four valves per cylinder
- Timing belt driven DOHC system
The redesigned ports improve torque and midrange efficiency. The
combustion chamber update allows higher compression without detonation.
NVCS enhances low rpm drivability while maintaining high rpm power.
The RB25DE NEO uses a multipoint electronic fuel injection (MPFI)
system.
Components include:
- Electric in tank fuel pump
- High-pressure fuel rail
- Multi-hole injectors (approx. 250-300 cc/min depending on version)
- Hotwire mass airflow sensor
- Engine Control Unit (ECU) with improved maps
- Throttle body
- Closed loop O2 sensor control
Fuel pressure approx. 36-43 psi depending on regulator.
The ECU uses input from:
- Oxygen sensor
- Crankshaft position sensor
- Camshaft position sensor
- Throttle position sensor
- Coolant temperature sensor
- Intake air temperature sensor
- Knock sensor
The lubrication system is full pressure wet sump with improvements over
earlier RB engines.
Specifications:
- Oil capacity 4.2-4.6 liters (4.4-4.9 US qt)
- Oil pressure 45-65 psi at 3,000 rpm; 15-20 psi at idle
- Recommended oil: 5W30, 10W30, or 10W40 synthetic
Features:
- Crankshaft driven trochoid oil pump
- Improved oil pickup and return passages
- Full flow spin-on oil filter
- Enhanced cooling around valve seats and combustion chamber
The cooling system is forced circulation liquid-cooled.
Components include:
- Belt-driven centrifugal water pump
- Aluminum radiator
- Thermostat
- Coolant expansion tank
- Electric cooling fans
- Block and head coolant galleries optimized for heat distribution
Specifications:
- Thermostat begins opening approx. 82°C (180°F)
- Fully open approx. 95°C (203°F)
- Cooling capacity 7.0-7.8 liters (7.4-8.2 US qt)
| Intake and Exhaust Systems |
Induction components:
- Air cleaner housing
- Paper air filter
- Hotwire MAF sensor
- Large diameter throttle body
- Redesigned long runner intake manifold
- Resonator chambers to reduce intake noise
The Nissan RB25DE NEO intake manifold provides improved torque characteristics
compared to earlier RB designs.
Exhaust system features:
- Cast stainless or cast-iron exhaust manifold
- Catalytic converter
- Primary O2 sensor
- Secondary O2 sensor on emissions regulated models
- Resonators and muffler tuned for low noise and smooth tone
Nissan RB25DE NEO manifolds improve exhaust flow and emissions compliance.
The RB25DE NEO uses a coil on plug electronic ignition system.
Components include:
- Six individual ignition coils
- Crank angle sensor
- Cam angle sensor
- Knock sensor
- ECM controlled ignition timing
- Platinum or iridium spark plugs
Sparkplug gap approx. 0.9-1.1 mm (0.035-0.043 in). Ignition timing
automatically adjusts to prevent knock under high compression.
- Length 780-830 mm (30.7-32.7 in)
- Width 630-650 mm (24.8-25.6 in)
- Height 690-720 mm (27.2-28.3 in)
Dry weight 165-185 kg (364-408 lb) depending on accessories.
Recommended intervals:
- Oil and filter: every 5,000-8,000 km (3,000-5,000 miles)
- Air filter: every 20,000 km
- Spark plugs: every 40,000-50,000 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. 170-200 psi. Cylinder 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)
- Connecting 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 lbft (24-30 Nm)
- Exhaust manifold nuts: approx. 25-30 lb-ft (34-40 Nm)
- Oil drain plug: approx. 25-30 lb-ft (34-40 Nm)
- Spark plugs: approx. 15-20 lb-ft (20-27 Nm)
The RB25DE NEO engine appeared in:
- Nissan Skyline R34 (non turbo trims)
- Nissan Stagea WC34 (late models)
- Nissan Laurel C35 (upper trims)
- Nissan Cedric / Gloria (limited markets)
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