The Nissan QG18DE is a 1.8 liter (1,769 cc, 107.94 cu in) straight-four 4-stroke natural aspirated gasoline engine from Nissan QG-family. The engine was produced since 1999 as substituted of the SR18DE and was discontinued in 2006. The Nissan QG18DE engine received the RJC Technology of The Year Award of 2001
The QG18DE motor has a cast-iron cylinder block and aluminum alloy cylinder head with two overhead camshafts (DOHC). The engine uses multi-point fuel injection system; variable valve timing system on the intake side (NVCT); electronic ignition system with individual ignition coil for each cylinder; electronic throttle body; intake manifold with vortex valves, ERG system, and three-way catalyst. The engine is also equipped with a mixture ratio self-learning control system. Redline is 6,500 rpm. The engine version without variable valve timing system (NVCT) was also available.
The engine has the same cylinder block with QG16DE, but cylinder bore is enlarged to 80.0 mm (3.15 in), piston stroke is the same 88.0 mm (3.46 in). Compression ratio is 9.5:1. It producted from 115 PS (85 KW; 114 HP) at 5,600 rpm to 125 PS (92 KW; 123 HP) at 5,600 rpm of horsepower and from 158 Nm (16.1 kg·m; 116.6 ft·lb) at 4,400 rpm to 165 Nm (16.8 kg·m; 121.8 ft·lb) at 4,400 rpm of torque.
The breakdown of the engine code is as follows:
- QG – Engine Family
- 18 – 1.8 Liter Displacement
- D – DOHC (Dual Overhead Camshafts)
- E – Multi Point Fuel Injection
Engine systems description
Engine Control System
The QG18DE engine uses the ECCS (Electronic Concentrated engine Control System). This system controls the fuel injection, ignition timing and idle RPM as one single control unit.
Multiport Fuel Injection System (MFI)
The amount of fuel injected from the fuel injector is determined by the engine ECM. The ECM controls the injection pulse duration. The amount of fuel injected is a program value in the ECM memory. The program value is preset by engine operating conditions. These conditions are determined by input signals from the crankshaft position sensor, camshaft position sensor, and the mass air flow sensor.
Two types of fuel enjection timing system are used.
- Sequential multiport fuel injection is used when the engine is running. Fuel is injected into each cylinder during each engine cycle according to the firing order.
- Semultaneous multiport fuel injection system is used when the engine is being started or if the fail-safe system is operating. Fuel is injected semultaneously into all four cylinders two times each engine cycle.
Electronic Ignition System (EI)
The Nissan QG18DE ignition system is controlled by the ECU to maintain the best air-fuel ratio for every running condition of the engine. The ignition timing data is stored in the ECM, this data forms the map shown. The ECM receives information such as the injection pulse width and camshaft position sensor signal. Computing this information, ignition signals are transmitted to the power transistor.
|Layout||Four stroke, Inline-4 (Straight-4)|
|Displacement||1.8 L, 1,769 cm3 (107.94 cu in)|
|Fuel system||Multi Point Fuel Injection (MFI)|
115 PS (85 KW; 114 HP) at 5,600 rpm
117 PS (86 KW; 115 HP) at 5,600 rpm
120 PS (88 KW; 118 HP) at 5,600 rpm
122 PS (90 KW; 121 HP) at 5,600 rpm
125 PS (92 KW; 123 HP) at 5,600 rpm
158 Nm (16.1 kg·m; 116.6 ft·lb) at 4,400 rpm
161 Nm (16.4 kg·m; 118.8 ft·lb) at 4,400 rpm
163 Nm (16.6 kg·m; 120.3 ft·lb) at 4,400 rpm
165 Nm (16.8 kg·m; 121.8 ft·lb) at 4,400 rpm
|Dimensions (L x H x W):||–|
The QG18DE motor has a cast-iron cylinder block, cylinder bore is 80.0 mm (3.15 in) and the piston stroke is 88.0 mm (3.46 in). The pistons are each fitted with two compression rings and a single oil ring. The compression ratio is 9.5:1.
The engine uses forged-steel connecting rods with 140.5 mm (5.53 in) length (center distance). The crankshaft main journal diameter is 49.95 mm (1.966 in) and pins journal diameter is 39.97 mm (1.57 in).
|Cylinder block alloy||Cast iron|
|Cylinder bore:||80.0 mm (3.150 in)|
|Piston stroke:||88.0 mm (3.465 in)|
|Number of piston rings (compression / oil):||2 / 1|
|Number of main bearings:||5|
|Block Height:||213.95-214.05 mm (8.4232-8.4271 in)|
|Cylinder inner diameter (standard):||80.000-80.010 mm (3.1496-3.1500 in)|
|Piston skirt diameter (standard):||79.965-79.975 mm (3.1482-3.1486 in)|
|Piston pin outer diameter:||18.989-19.001 mm (0.7476-0.7481 in)|
|Piston ring side clearance:||Top||0.040-0.080 mm (0.0016-0.0031 in)|
|Second||0.030-0.070 mm (0.0012-0.0028 in)|
|Oil||0.045-0.155 mm (0.0018-0.0061 in)|
|Piston ring end gap:||Top||0.20-0.30 mm (0.0079-0.0118 in)|
|Second||0.32-0.47 mm (0.0126-0.0185 in)|
|Oil||0.20-0.60 mm (0.0079-0.0236 in)|
|Connecting rod center distance:||140.45-140.55 mm (5.5295-5.5335 in)|
|Connectin rod small end inner diameter:||19.000-19.012 mm (0.7480-0.7485 in)|
|Connectin rod big end inner diameter:||43.000-43.013 mm (1.6929-1.6934 in)|
|Crankshaft journal diameter:||49.956-49.964 mm (1.9668-1.9671 in)|
|Crankpin diameter:||39.968-39.974 mm (1.5735-1.5738 in)|
|Crankshaft center distance:||43.95-44.05 mm (1.7303-1.7342 in)|
The engine has an aluminum cylinder head with two chain-driven overhead single-piece cast camshafts and sixteen valves (four per cylinder). The QG18DE has a single timing chain. Intake valves are 30.0 mm (1.18 in) in diameter and the exhaust valves are 25.0 mm (0.99). Intake valves duration is 236° and exhaust valves duration is 222° for engines with valve timing control system and 222°/222°, respectively for engines without NVCTS.
The QG18DE does not have hydraulic lifters, so special shims are used to adjust the valve clearance.
|Cylinder head alloy||Aluminum|
|Cylinder head height:||118 mm (4.6456 in)|
|Valve Arrangement:||DOHC, chain drive|
236° for NVCTS engine|
222° for non NVCTS engine
|Exhaust duration:||222° for NVCT and non NVCT engine|
|Valve head diameter:||INTAKE||29.9-30.2 mm (1.177-1.189 in)|
|EXHAUST||24.9-25.2 mm (0.980-0.992 in)|
|Valve length:||INTAKE||92.00-92.50 mm (3.6220-3.6417 in)|
|EXHAUST||92.37-92.87 mm (3.6366-3.6563 in)|
|Valve stem diameter:||INTAKE||5.465-5.480 mm (0.2152-0.2157 in)|
|EXHAUST||5.445-5.460 mm (0.2144-0.2150 in)||Cam height (QG18DE with intake valve timing control):||INTAKE||40.610-40.800 mm (1.5988-1.6063 in)|
|EXHAUST||40.056-40.246 mm (1.5770-1.5845 in)|
|Outer camshaft journal diameter:||№1||27.935-27.955 mm (1.0998-1.1006 in)|
|№2-5||23.935-23.955 mm (0.9423 – 0.9431 in)|
Head tightening procedure and torque specs:
- Step 1: 29.4 Nm; 3.0 kg·m; 22 ft·lb
- Step 2: 58.8 Nm; 6.0 kg·m; 43 ft·lb
- Step 3: Loosen all bolts completely
- Step 4: 29.4 Nm; 3.0 kg·m; 22 ft·lb
- Step 5: Turn main bolts 50-55° or 58.8 Nm; 6.0 kg·m; 43 ft·lb
|Valve clearance (HOT)|
|Intake valve||0.32-0.40 mm (0.013-0.016 in)|
|Exhaust valve||0.37-0.45 mm (0.015-0.018 in)|
|Standard||13.5 kg/cm2 (13.25 bar, 192 psi) / 350 rpm|
|Minimun||11.5 kg/cm2 (11.28 bar, 164 psi) / 350 rpm|
|Compression differential limit between cylinders||1 kg/cm2 (0.98 bar, 14 psi) / 350 rpm|
|Oil consumption , L/1000 km (qt. per miles)||up to 0.5 (1 qt. per 1200 miles)|
|Recommended engine oil||
|Oil type API||SE, SF, SG, SH or SJ|
|Engine oil capacity (Refill capacity)||
With filter change 2.7 l
Without filter change 2.5 l
|Oil change interval, km (miles)||10,000 (6,000)|
|Oil Pressure, kPa (bar, kg/cm2 , psi)||
Idle speed: More than 98 (0.98, 1.0, 14)
2,000 rpm: More than 294 (2.94, 3.0, 43)
6,000 rpm: More than 392 (3.92, 4.0, 57)
Standard: BKR5E-11 (NGK), RC10YC4 (Champion)|
Hot: BKR4E-11 (NGL)
Cold: BKR6E-11 (NGK)
|Spark plug gap||1.0 – 1.1 mm (0.039 – 0.043 in)|
|Spark plug torque||19.6-29.4 Nm (2.00-3.00 kg⋅m, 14.3-21.7 lb·ft)|
Valve clearance adjustment data
Calculate the thickness of new adjusting shim so valve clearance comes within specified values.
R = Thickness of removed shim
N = Thickness of new shim
M = Measured valve clearance
N = R + [M – 0.37 mm (0.0146 in)]
N = R + [M – 0.40 mm (0.0157 in)]
Shims are available in 50 sizes from 2.00 mm (0.0787 in) to 2.98 mm (0.1173 in), in steps of 0.02 mm (0.0008 in).
Example (intake valve):
R = 2.10 mm
M = 0.52 mm
N = 2.10 + (0.52 – 0.37) = 2.25 mm, so we need a shim with code 225.
|For adjusting||For checking|
|Intake||0.32-0.40 mm (0.013-0.016 in)||0.25-0.33 mm (0.010-0.013 in)||0.21-0.49 mm (0.008-0.019 in)|
|Exhaust||0.37-0.45 mm (0.015-0.018 in)||0.32-0.40 mm (0.013-0.016 in)||0.30-0.58 mm (0.012-0.023 in)|
*: At a temperature of approximately 20°C (68°F)
Whenever valve clearances are adjusted to cold specifications, check that the clearances satisfy hot specifications and adjust again if necessary.
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