Volvo Engine Petrol 4 (VEP4) | VEA

Introduction

The Volvo Engine Architecture (VEA) was a family of modular petrol I3, petrol I4 and diesel I4 engines that commenced production in May 2013 at Volvo’s plant in Skövde, Sweden. Volvo marketed its VEA engines using the ‘Drive-E’ designation.

The four-cylinder VEA range consisted of two basic engines – theVED4 common rail diesel engine and the VEP4 direct-injection petrol engine – that were developed to power vehicles underpinned by Volvo’s SPA (Scalable Platform Architecture) and CMA (C-platform Modular Architecture) platforms. As such, the VEA engines effectively replaced eight engine architectures for three platforms. According to Volvo, VEA reduced the number of unique parts by 60 percent, thereby improving manufacturing efficiency and quality assurance.

All versions of the VEA were manufactured on the same production line. For this, the production line had to be re-modelled for cylinder block processing and thirty machining cells were replaced or converted at a cost of about 500,000,000 SEK. In total, around 2,000,000,000 SEK was invested in the Skövde plant for production of the VEA engines.

Initially, Volvo’s VEP4 engine range had a capacity of 1969 cc. In 2015, however, Volvo introduced 1498 cc VEP4 engines. This article will consider the 1969 cc VEP4 and VED4 VEA engines, before summarising the differences between the 1969 cc and 1498 cc VEP4 engines.

VEP4 and VED4 (1969 cc) commonalities

The 1969 cc VEP4 and VED4 engines had the following commonalities:

• A high-pressure die-cast aluminium crankcase and bedplate with nodular cast iron bearings. The bearings had a 60 mm diameter for the T6, T5, D5 and D4 engines, and a 53 mm diameter for the T4, T3, D3 and D2 engines. Beyond this, the cylinders had 82.0 mm bores – spaced at 91.0 mm intervals – and a stroke of 93.2 mm for a capacity of 1969 cc. Within the cylinder bores, VEA engines had cast iron liners that were sprayed with eutectic aluminium to develop a strong bond to the block, improve heat transfer and reduce distortion under load;
• The crankshaft and connecting rods were machined from a forged blank, while the crankshaft had reinforcing cast iron bearings;
• For the pistons, the top piston ring had a Physical Vapour Deposition-coating (PVC) to reduce friction and the piston pins had a Diamond-like Carbon (DLC) coating. Within the cylinder block, oil jets sprayed the undersides of the piston to reduce operating temperatures. For VEA engines, different machining of the piston top was used to achieve different compression ratios;
• Double overhead camshafts. A belt in front of the engine drove the exhaust camshaft with a timing belt pulley, while the intake camshaft was driven by the exhaust camshaft via gears in the rear of the engine;
• BorgWarner turbochargers;
• A one-piece aluminium housing for the counter-rotating balance shafts which operated on needle bearings. Please note, however, that the VED4 D3 and D2 engines did not have balancer shafts because its shorter pistons, lighter connecting rods and smaller piston pins reduced reciprocating masses by 20 per cent and, in turn, vibration. Similarly, the 1498 cc VEP4 engines also omitted balance shafts; and,
• A chain-driven variable oil pump (pressure ranged from 1.5 to 4.5 bar) in which pressure was controlled by a solenoid actuator.

To reduce friction, the VEA engines introduced an improved surface treatment for the cylinder bores and crankshaft, and thinner 0W20 synthetic engine oil. The VEA engines have also been designed to support ‘electrification’ whereby components such as an Integrated Starter Generator (ISG) could be connected easily. The compact dimensions of the VEA engine also meant that an electric motor could be fitted in the front or rear of the vehicle, with a battery pack positioned in the centre of the car.For an example of such an application, please see Volvo VEP4 T8 Twin Engine. 

Unique features of the 1969 cc VEP4 engine

Compared to the 1969 cc VED4 engines, unique features for the VEP4 engines included:

• For VEP4 engines, the cylinder head was made from AlSi7 aluminium alloy and subjected to T7 heat treatment;
• The double overhead camshafts were made from cast-iron and each had a phaser for variable valve timing. To reduce friction, the first cam bearing position used roller bearings;
• The four valves per cylinder were actuated by solid (or mechanical) tappets which had a diamond-like carbon (DLC) coating to reduce friction;
• The timing belt was 23 mm wide (compared to 28 mm for the VED4) and provided drive for the double cam phase and electrical water pump;
• The turbine housings were produced from sheet-metal and integrated with the exhaust manifold;
• The fuel pump generated pressure of 200 bar and fuel was injected into the cylinders by centrally-positioned six-hole solenoid injectors. On start-up, a stratified charge could be used for faster warm-up of the catalytic converters. According to Volvo, direct injection also provided better low-end torque than conventional port injection due to scavenging effects and charge air cooling;
• The spark plugs were centrally mounted in the roof of the combustion chamber (compared to side-mounted glow plugs for the VED4);
• Cooling system/thermal management: the outer cooling system differed for petrol and diesel engines because diesel engines had higher heat rejection at full load and lower heat rejection at part load and during warm-up. While VED4 diesel engines had a mechanical water pump, the VEP4 engines had a 400 watt fully variable electric water pump.

VEP4 T6 engines: supercharger and double water jacket

The VEP4 T6 engines were equipped with a turbocharger and a roots-type Eaton supercharger which was driven by the front-end accessory drive. The supercharger had an integrated clutch, two rotors and four lobes with 160 degree twist. The supercharger operated from idle to 3500 rpm and provided peak boost pressure of 0.6 bar. At 3500 rpm, however, the supercharger was de-clutched so that only the turbocharger operated. In contrast to the VEP4 T5 engines which had a single water jacket, the VEP4 T6 engines had a double water jacket to enhance cooling and flow.

1498 cc VEP4 engines

In 2015, Volvo introduced 1498 cc VEP4 petrol engines for the ‘2016 model year’. These engines differed from their 1969 cc counterparts in that:

• Stroke was reduced from 93.2 mm to 70.9 mm;
• Balancer shafts were omitted; and,
• All 1498 cc VEP4 engines had a compression ratio of 10.5:1.