The VR5 engines are a family of gasoline internal combustion engines developed by the Volkswagen Group and produced from 1997 to 2006. They are derived from the VR6 engine family, also developed by Volkswagen, but with one less cylinder. VR5 engines are narrow angle V5 petrol engines, with a V angle of 15° and a displacement of 2,324 cc (2.3 L; 141.8 cu in).The VR5 was the first production block to use five cylinders in a V design with a 15 degree angle.
A VR5 engine block consists of two cylinder banks, one bank containing three cylinders and the other containing two. In a transverse layout the three cylinder bank is located towards the front and in a longitudinal layout towards the right. Due to the narrow angle the cylinder arrangement appears like a staggered inline five cylinder.
The VR5 was initially made with 2 valves per cylinder as the AGZ engine from 1997 until 2000, resulting in a 10 valve engine producing 150 PS (110 kW; 148 hp) at 6000 RPM and 209 N⋅m (154 lb⋅ft) of torque at 3200 RPM. The engine was updated in 2000 as the AQN/AZX engine adding an additional 2 valves per cylinder and variable valve timing, resulting in an 20 valve engine now with 4 valves per cylinder, producing 170 PS (125 kW; 168 hp) at 6200 RPM and 220 N⋅m (162 lb⋅ft) at 3300 RPM. Both versions of the engine had cast aluminium alloy cylinder heads and cast iron cylinder blocks. 
Valvetrain and cylinder head
The AGZ engine was the first version of the VR5. It had ten valves in total, with two unequal sized valves per cylinder and chain driven camshafts. Due to the use of a single cylinder head, a key design principle of the VR engines, exhaust and intake ports where of unequal length between the two cylinder banks. To mitigate this, Volkswagen used unequally sized valves in order to ensure even flow and power output from the cylinders.
Engine block and pistons
The AGZ engine used a cast iron cylinder block with five staggered cylinders. Each cylinder was 81.0 mm × 90.2 mm (3.19 in × 3.55 in) bore x stroke, resulting in 464.8 cc (28.4 cu in) per cylinder with a 0.90:1 stroke ratio (undersquare/long stroke). The tops of the pistons were angled to accommodate for the use of the 15° narrow V angle.
Aspiration, fuel system, and engine management
The AGZ engine was managed by a Bosch Motronic M3.8.3 engine management system. The engine used multi-point common rail fuel injection, with fuel injected indirectly into the lower intake manifold section just before the cylinder head intake ports. Fuel and air delivery was controlled by a cable operated throttle body, with a potentiometer monitoring throttle position and allowing the Motronic ECU to deliver the correct amount of fuel. The engine also had a vacuum actuated variable intake manifold operated by a solenoid air valve controlled by the ECU dependent on engine load and speed. This allows the engine to take advantage of pressure waves created by the intake valves opening and closing. This higher pressure air is stored in a section of the intake manifold behind the vacuum operated valve and released under certain engine conditions, allowing higher pressure air to enter the engine resulting in increased power output.
|Engine Code||Production||Displacement||Power(PS)||Torque||Compression Ratio|
|AGZ||1997-2000||2324 cc||150 @ 6000 RPM||209 N⋅m (154 lb⋅ft) @ 3200 RPM||10:1|
|AQN/AZX||2000-2006||2324 cc||170 @ 6200 RPM||220 N⋅m (162 lb⋅ft) @ 3300 RPM||10.8:1|
- "List of discontinued Volkswagen Group petrol engines", Wikipedia, 2019-04-30, retrieved 2019-05-01
- "Self-Study Programme 195 The 2.3 ltr V5 Engine - Volkspage" (PDF). Volkspage. 01/05/19. Archived from the original (PDF) on 08/05/19. Check date values in: