Nissan VQ20DE Specifications
| Engine Model: Nissan VQ20DE |
| Engine Type: 4-cycle 6-cylinder V-block DOHC 24-valve liquid-cooled gasoline |
| Total Displacement: 121.7 cu.in (1.99 L) |
| Rated Engine Power: 147-158 Hp (110-118 kW) at 6400 rpm |
| Fuel System Type: Sequential multi-point fuel injection |
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The Nissan VQ20DE is a 2.0-liter, naturally aspirated
V6 gasoline engine produced from 1994 through 2003 as the smallest displacement
member of the VQ engine family. The VQ series, introduced as Nissan’s
next-generation V6 architecture to replace the VG family, was engineered with a
focus on reduced weight, compact dimensions, and enhanced refinement.
The VQ20DE was developed primarily for the Japanese and European markets, where
displacement-based taxation structures made a 2.0-liter V6 an attractive
proposition for mid-sized sedans requiring the smoothness of a six-cylinder
engine without the displacement penalty of larger 2.5-liter or 3.0-liter
variants. The engine’s architecture is defined by its all-aluminum construction,
featuring a cast aluminum cylinder block and cylinder heads, a 60-degree V-angle
retained for inherent balance, and a silent timing chain drive that eliminated
the maintenance requirements of belt-driven systems.
The VQ20DE served as the entry-level V6 offering in the Nissan Cefiro, Maxima,
and QX models, providing a level of operational smoothness that distinguished it
from four-cylinder competitors while delivering adequate power for urban and
highway driving.
The VQ20DE engine exemplifies the design philosophy that would make the VQ
family one of the most acclaimed V6 architectures in automotive history, with
the series earning multiple places on the Ward’s 10 Best Engines list. The
engine’s all-aluminum construction achieves a significant weight reduction
compared to the cast iron-block VG engines it succeeded, improving vehicle
dynamics and fuel efficiency.
The 60-degree V-angle, combined with a rigid aluminum block and a fully
counterweighted forged steel crankshaft, provides inherent balance that results
in exceptionally low vibration levels across the engine speed range. The
cylinder heads feature a dual overhead camshaft (DOHC) arrangement with four
valves per cylinder, actuated via hydraulic lash adjusters and roller rocker
arms, eliminating the requirement for valve clearance adjustments. The
micro-finishing process applied to the crankshaft and camshaft journals reduces
friction, contributing to both smoothness and fuel economy.
The timing chain system, with its hydraulic tensioner, operates with low noise
and requires no scheduled replacement under normal service conditions. The
VQ20DE’s power output, ranging from 148 to 158 horsepower depending on market
and compression ratio, is modest by modern standards, but its torque delivery is
characterized by a broad, flat curve that suits the engine’s intended
applications in sedans focused on comfort rather than outright performance. The
engine’s refinement at idle and under acceleration remains one of its defining
characteristics, with the VQ20DE often cited as one of the smoothest 2.0-liter
V6 engines ever placed into series production.
Production Period: 1994-2003.
Engine Code: VQ20DE.
Configuration: 60° V6.
Displacement: 1,995 cc (121.7 cu.in).
Bore: 76.0 mm (2.99 in).
Stroke: 73.3 mm (2.89 in).
Firing Order: 1-2-3-4-5-6.
Compression Ratio: 9.5:1 (European markets).
Compression Ratio: 10.0:1 (Japanese domestic market).
Combustion System: Sequential multipoint fuel injection (SMPFI).
Aspiration: Naturally aspirated.
Valvetrain: DOHC, 24 valves (4 per cylinder).
Maximum Engine Speed: 7,000 rpm (redline).
Maximum Power (9.5:1 Compression): 148 hp (110 kW) @ 6,400 rpm.
Maximum Power (10.0:1 Compression): 158 hp (118 kW) @ 6,400 rpm.
Maximum Torque (9.5:1 Compression): 137 lb-ft (186 Nm) @ 4,400 rpm.
Maximum Torque (10.0:1 Compression): 145 lb-ft (197 Nm) @ 4,400 rpm.
The VQ20DE cylinder block is manufactured from cast
aluminum alloy, utilizing a 60-degree V-angle that provides inherent primary and
secondary balance without the requirement for balance shafts. The open-deck
design at the top of the cylinder bores reduces weight while maintaining
adequate structural integrity for naturally aspirated operation. Cast iron
cylinder liners are inserted during the casting process, providing a durable
wear surface for the piston rings. The block features a deep-skirt design that
extends below the crankshaft centerline, contributing to reduced vibration and
improved main bearing alignment.
Four main bearings support the crankshaft, with the bearing caps integrated into
a structural aluminum ladder frame that also serves as the lower crankcase. The
crankshaft is constructed from forged steel with full counterweights, a feature
that contributes to the engine’s ability to sustain high engine speeds with
minimal vibration. Oil jets are integrated into the block, directed at the
underside of the pistons to provide cooling and reduce thermal stress under
sustained high-load operation.
The cylinder heads are manufactured from cast aluminum
alloy, with separate heads for each cylinder bank. Each head incorporates dual
overhead camshafts, with the camshafts driven by a silent timing chain system.
The valvetrain utilizes 24 valves total, with each cylinder served by two intake
valves and two exhaust valves. The valves are actuated via roller rocker arms
mounted on a shaft, with hydraulic lash adjusters integrated into the rocker
arms. This arrangement eliminates the requirement for manual valve clearance
adjustments and reduces valvetrain noise.
The intake valves measure 32.5 mm (1.28 in) in diameter, while the exhaust
valves measure 28.0 mm (1.10 in). The combustion chamber is a pent-roof design
with centrally positioned spark plugs, optimized for flame propagation and
thermal efficiency. The camshafts are hollow to reduce rotational mass, and the
camshaft journals are micro-finished to reduce friction. The cylinder head
incorporates the intake and exhaust ports on opposite sides, with the intake
ports designed to generate swirl within the combustion chamber to enhance
air-fuel mixing.
The fuel system utilizes sequential multipoint fuel
injection, with a fuel injector positioned at each intake port. The system
operates at a nominal fuel pressure of 3.0 bar (44 psi), regulated by a fuel
pressure regulator mounted on the fuel rail. Fuel is delivered from an in-tank
fuel pump through a filter and to the dual fuel rails - one for each cylinder
bank - constructed from stainless steel.
The injectors are sequentially fired by the engine control unit based on signals
from the crankshaft position sensor and camshaft position sensors. The engine
control unit calculates injector pulse width using inputs including mass
airflow, engine speed, throttle position, coolant temperature, and exhaust
oxygen sensor feedback. A hot-wire mass airflow sensor is located in the intake
tract, providing precise measurement of incoming air mass. The fuel system is
returnless on later variants, with the pressure regulator integrated into the
fuel pump module within the fuel tank to reduce fuel heating and evaporative
emissions.
The lubrication system employs a wet-sump design with a
gear-type oil pump mounted within the front timing cover, driven directly by the
crankshaft. The pump incorporates a relief valve to maintain consistent oil
pressure across the engine speed range. Oil is drawn from the sump through a
screened pickup tube and delivered through a full-flow spin-on oil filter
mounted on the cylinder block.
The filtered oil is distributed through internal galleries to the crankshaft
main bearings, connecting rod bearings, camshaft bearings, and the hydraulic
lash adjusters. Dedicated piston cooling oil jets are supplied from the main oil
gallery, directing a stream of oil to the underside of each piston crown to
manage combustion temperatures. An oil cooler is integrated into the system on
certain applications, utilizing engine coolant to maintain oil temperature.
Total system capacity, including the filter, is 4.5 to 5.0 liters (4.8 to 5.3
qt) depending on the vehicle application.
The cooling system is a pressurized water-cooled design
utilizing a crossflow aluminum radiator with plastic end tanks. A centrifugal
water pump, driven by the timing chain, circulates coolant through the cylinder
block, cylinder heads, and radiator. The water pump is a service item with a
lifespan commensurate with the cooling system maintenance interval. A
wax-element thermostat is positioned in the coolant outlet housing, with a
nominal opening temperature of 76.5°C (170°F). The system incorporates an
expansion tank to accommodate coolant expansion and to facilitate air removal.
An electric cooling fan, controlled by the engine control unit, provides airflow
across the radiator during low-speed operation and stationary idle. The cooling
system is designed to maintain consistent operating temperatures across the two
cylinder banks, with the water pump and thermostat housing positioned centrally
to ensure balanced coolant distribution. Coolant capacity varies by vehicle
application but generally ranges from 7.0 to 8.0 liters (7.4 to 8.5 qt).
| Intake and Exhaust Systems |
Intake System: The intake system consists of an air
cleaner housing with a replaceable dry-type filter element, a hot-wire mass
airflow sensor, and an aluminum intake manifold. The intake manifold
incorporates a plenum chamber that feeds individual runners to each cylinder
head. The runner length is tuned to optimize torque delivery across the engine
speed range. The manifold incorporates a resonance chamber to reduce intake
noise and a variable intake system on certain applications to adjust runner
length based on engine speed.
Exhaust System: The exhaust system utilizes a cast iron exhaust manifold on each
cylinder bank. The system incorporates oxygen sensors upstream of the catalytic
converters for closed-loop fuel control, with downstream sensors on later models
for catalyst monitoring. The exhaust pipes merge downstream of the converters
into a single system with a resonator and muffler.
| Ignition and Electrical System |
Ignition System: The ignition system utilizes a
distributorless design with individual ignition coils mounted directly over each
spark plug in a coil-on-plug configuration. This arrangement eliminates
high-tension ignition wires, reducing electromagnetic interference and ensuring
consistent spark energy delivery. The engine control unit manages ignition
timing based on inputs including engine speed, load, knock sensor feedback, and
intake air temperature.
Electrical System: The engine is equipped with a 12-volt electrical system. The
starter motor is a reduction-gear type, sized to provide adequate cranking
torque for the compression ratio. The alternator is belt-driven from the
crankshaft pulley and provides charging current for the battery and vehicle
electrical loads. The engine control unit utilizes a 16-bit or 32-bit processor
depending on the model year, with integrated control for fuel injection,
ignition timing, and variable intake systems.
Overall Length: 640 mm (25.2 in)
Overall Width: 670 mm (26.4 in)
Overall Height: 650 mm (25.6 in)
Dry Weight (complete engine): 145 kg (320 lbs)
Engine Oil: SAE 5W-30, 10W-30, 5W-40 API SG or higher;
synthetic oil recommended.
Oil Capacity (with filter change): 4.5-5.0 L (4.8-5.3 qt).
Oil Change Interval: 5,000-7,500 km (3,100-4,700 mi) under normal conditions.
Spark Plug Type: NGK PFR5G-11 or equivalent platinum-tipped plug.
Spark Plug Gap: 1.1 mm (0.043 in).
Spark Plug Change Interval: 96,000 km (60,000 mi).
Coolant Capacity: 7.0-8.0 L (7.4-8.5 qt) depending on vehicle platform.
Coolant Specification: Ethylene glycol-based antifreeze with corrosion
inhibitors.
Coolant Change Interval: Replace every 2 years or 40,000 km (24,800 mi).
Engine Idle Speed: 650-750 rpm.
Compression Pressure: Standard: 1.4-1.6 MPa (203-232 psi).
Compression Pressure: Minimum service limit: 1.2 MPa (174 psi).
Connecting Rod Cap Bolts: 45 Nm (33 lb-ft) + 60° to 75°
turn
Main Bearing Cap Bolts: 40 Nm (30 lb-ft) + 60° to 75°
Cylinder Head Bolts, Stage 1: 30 Nm (22 lb-ft)
Cylinder Head Bolts, Stage 2: 60 Nm (44 lb-ft) +90° + 90°
Camshaft Bearing Caps: 15 Nm (11 lb-ft) for M6
Camshaft Bearing Caps: 25 Nm (18 lb-ft) for M8
Intake Manifold to Cylinder Head: 20-25 Nm (15-18 lb-ft)
Exhaust Manifold to Cylinder Head: 30-35 Nm (22-26 lb-ft)
Flywheel/Flexplate to Crankshaft: 100 Nm (74 lb-ft) + 60° to 75° turn
Spark Plugs: 25 Nm (18 lb-ft)
Oil Filter Housing to Block: 25 Nm (18 lb-ft)
Water Pump Mounting: 20 Nm (15 lb-ft)
Nissan Cefiro: A32 Series (1994-1998): Cefiro 2.0-liter
variants for Japanese domestic market and Southeast Asian markets. A33 Series
(1998-2003): Cefiro 2.0-liter variants, the final application of the VQ20DE in
this model line.
Nissan Maxima (Japanese Domestic Market): A32 Series (1995-1998): Maxima
2.0-liter variants for Japanese market, marketed as the Nissan Maxima QX in some
regions. A33 Series (1998-2003): Maxima 2.0-liter variants for Japanese domestic
market.
Nissan QX (European Market): A32 Series (1995-1998): Nissan QX 2.0-liter
variants for European markets, representing the Maxima under a different name.
A33 Series (1998-2003): Nissan QX 2.0-liter variants for European markets.
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