Introduction
The Volkswagen Mk.4 Golf R32 was powered by a 3.2-litre VR6 petrol engine (codes: BFH and BML) which was a member of Volkswagen’s EA390 engine family. Key features of the Golf R32’s BFH/BML engines included its:
- Grey cast iron block;
- Die-forged steel crankshaft which operated on seven main bearings;
- 15 degree ‘V’ angle between its cylinder banks;
- Single cast aluminium alloy cylinder head for both cylinder banks;
- Double overhead camshafts driven by a simplex roller chain;
- Four valves per cylinder;
- Variable intake and exhaust valve timing;
- Twin path intake manifold; and,
- Compression ratio of 11.25:1.
| Model | Engine | Trans. | Peak power | Peak torque |
|---|---|---|---|---|
| Volkswagen Mk.4 Golf R32 | 3.2-litre BFH/BML VR6 | 6sp man. | 177kW at 6250rpm | 320Nm at 2800-3200rpm |
Block and crankshaft
The 3.2-litre VR6 engine had a grey cast iron block with 84.0 mm bores and a 95.9 mm stroke for a capacity of 3189 cc. The centreline of the cylinders was offset from the crankshaft by 12.5 mm, while the connecting rod bearing journals were offset 22 degrees to each other for a 120 degree firing interval between the cylinders and to accommodate the offset cylinder placement and narrow 15 degree ‘V’ angle.
The VR6 engine had a die-forged steel crankshaft which operated on seven main bearings.
Cylinder head and valvetrain
The 3.2-litre VR6 engine had a single cast aluminium alloy cylinder head rather than separate cylinder heads for wider angle ‘V’ engines. Within the cylinder head, the VR6 engine had double overhead camshafts – driven by a simplex roller chain – whereby the front camshaft operated the intake valves and the rear camshaft operated the exhaust valves. Each camshaft had twelve (12) cam lobes.
For the 3.2-litre VR6 engine, both the intake and exhaust camshafts were continuously adjusted variable via a vane pump regulator. The intake camshaft provided a 52 degree range of adjustment for the intake valves, while the exhaust camshaft provided a 22 degree range for the exhaust valves. Furthermore, the VR6 engine had four unequal-length valves per cylinder that were actuated by roller rocker arms with automatic hydraulic clearance compensation.
Twin-path intake manifold
The 3.2-litre VR6 engine had a twin-path intake manifold in which manifold length was controlled by the ECU. To change take port lengths, the ECU would activate a solenoid valve that admitted partial pressure into the vacuum box and, in turn, the vacuum box would actuate the rotary valve. Generally,
- At low engine speeds: the short path was used to reduce noise;
- Medium engine speeds: the long path was used to increase torque; and,
- High engine speeds or wide open throttle: the short path was used to boost top-end power.
Injection and ignition
The 3.2-litre VR6 engine had electronic sequential multi-point injection with the fuel injectors mounted behind the bend of the intake manifold. The EA390 engine had distributorless electronic ignition whereby each cylinder had its own ignition coil. Furthermore, the Bosch Motronic ME 7.1.1 engine management system controlled the following functions:
- Electronic throttle valve operation;
- Control of the inner exhaust gas recirculation via the camshaft adjustment;
- Secondary air injection; and,
- Electronically-regulated fan control.
The VR6 engine had a compression ratio of 11.25:1 and 1-5-3-6-2-5-4 firing order.
