Nissan MR20DD

The Nissan MR20DD is a 2.0 l (1,997 cc, 121,68 cu.in.) straight-four 4-stroke natural aspirated gasoline engine from Nissan MR-family.

The MR20DD features lightweight aluminum block with the fully balanced five-bearings crankshaft and aluminum head with two camshafts (DOHC) and four valves per cylinder. Compression ratio rating is 11.2:1. Cylinder bore and the piston stroke are 84.0 mm (3.3 in) and 90.1 mm (3.54 in), respectively.

The MR20DD engine is equipped with the direct injection fuel system, electronic throttle, Twin CVTC (continuous variable valve timing system) on both the intake and exhaust camshafts, EGR system and electronic ignition with individual coils on each spark plug (NDIS).

It produces from 144 PS (106 KW; 142 HP) at 5,600 rpm to 150 PS (110 KW; 148 HP) at 6,000 rpm of horsepower and from 200 Nm (20.4 kg·m; 147.6 ft·lb) at 4,400 rpm to 210 Nm (21.4 kg·m; 155.0 ft·lb) at 4,400 rpm of torque.

The breakdown of the engine code is as follows:

• MR – Engine Family
• 20 – 2.0 Liter Displacement
• D – DOHC (Dual Overhead Camshafts)
• D – Direct Injection

General information

Cylinder block

Cylinders in the Nissan MR20DD engines are fitted at an offset to minimize friction arising from the angle of the connecting rod as a piston descends into the cylinder. The crankshaft and camshaft journals are finished with a polishing tape to produce a mirror-like finish. The result is a thorough reduction in friction on these bearing surfaces of key engine components. Each piston is equipped with two compression and single oil control ring.

Main bearing cap bolts tightening procedure and torque specs:

• Step 1: 34.3 Nm; 3.5 kg·m; 25 ft·lb
• Step 2: Turn all bolts 60°

After securing bearing cap bolts, make sure crankshaft turns smoothly by hand.

Connecting rod bearing bolts

• Step 1: 27.4 Nm; 2.8 kg·m; 20 ft·lb
• Step 2: 0 Nm; 0 kg·m; 0 ft·lb
• Step 3: 19.6 Nm; 2.0 kg·m; 14 ft·lb

Crankshaft pulley bolt

• Step 1: 68.6 Nm; 7.0 kg·m; 51 ft·lb
• Step 2: 0 Nm; 0 kg·m; 0 ft·lb
• Step 3: 29.4 Nm; 3.0 kg·m; 22 ft·lb

Flywheel (M/T) or Drive plate (CVT) fixing bolts

• 108 Nm; 11 kg·m; 80 ft·lb

Cylinder head

The cylinder head is made of strong, light aluminum alloy which gives it good cooling efficiency. Each camshaft is supported by five bearings. The MR20DD has continuous variable valve timing system (C-VTC) on both the intake and exhaust camshafts. C-VTC enables variable valve timing in response to engine rpm and throttle opening. Enhanced control and reduced system friction improve response and optimize torque characteristics.

Intake valves are 34.0 mm (1.34 in) in diameter, intake duration is 240°, and the exhaust valves are 27.7 mm (1.09 in), exhaust duration is 220°. The MR20DD motor does not have hydraulic lifters, so special valve lifters are used to adjust the valve clearance.

Head tightening procedure and torque specs:

• Step 1: 40 Nm; 4.1 kg·m; 30 ft·lb
• Step 2: Turn all bolts 100°
• Step 3: Loosen all bolts completely
• Step 4: 40 Nm; 4.1 kg·m; 30 ft·lb
• Step 5: Turn all bolts 100°
• Step 6: Turn all bolts another 100°

Camshaft sprocket bolts

• Intake: 35.0 Nm; 3.6 kg·m; 26 ft·lb
• Exhaust: 88.2 Nm; 9.0 kg·m; 65 ft·lb

Maintenance data

Valve clearance adjustment data

Calculate the thickness of new adjusting valve lifter so valve clearance comes within specified values.

R = Thickness of removed valve lifter
N = Thickness of new valve lifter
M = Measured valve clearance

Intake:
N = R + [M – 0.30 mm (0.012 in)]
Exhaust:
N = R + [M – 0.33 mm (0.013 in)]

Valve lifters are available in 26 sizes range from 3.00 mm (0.1181 in) to 3.50 mm (0.1378 in), in steps of 0.02 mm (0.0008 in).

Example (intake valve):
R = 3.10 mm
M = 0.52 mm
N = 3.10 + (0.52 – 0.30) = 3.32 mm, so we need a valve lifter with identification mark 332H.

Vehicle applications

Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.