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 V5petrol engines, with a V angle of 15° and a displacement of. The VR5 was the first production block to use five cylinders in a V design with a 15-degree angle.
Technical Information
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 engines have a firing order of 1-2-4-5-3. 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 at 6000 RPM and 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 at 6200 RPM and at 3300 RPM. Both versions of the engine had cast aluminium alloy cylinder heads and cast ironcylinder blocks.
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 were of unequal length between the two cylinder banks. To mitigate this, Volkswagen used unequally sized valves to ensure even flow and power output from the cylinders.
The AGZ engine used a cast iron cylinder block with five staggered cylinders. Each cylinder was bore x stroke, resulting in per cylinder with a 0.90:1 stroke ratio. The top of each piston was angled to accommodate for the use of the 15° narrow V angle.
The AGZ engine was managed by a Bosch Motronic M3.8.3 engine management system. The engine used multi-point common railsequential 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, controlled by the ECU via a valve part of the engines vacuum system. The valve is opened and closed depending on engine load, engine speed and throttle position. This allows the engine to take advantage of pressure waves created by the intake valves opening and closing.
