|The new compact inline-six|
Volvo has introduced a new high-efficiency, compact six-cylinder engine to accompany its all new Volvo S80.
The new six-cylinder engine, designed by Volvo, is of an all-new, compact design. Its main structure is made entirely of aluminium and has a larger displacement than its predecessor, 3.2 liters as against the previous 2.9. Power increases to 175 kW (235 hp) as is torque, at 320 Nm.
This corresponds to increases of 31 kW (+21.5%) and 40 Nm (+14.2%) respectively. Fuel consumption decreases 0.7 l/100km to 9.9 l/100km (24 mpg), a 7% decrease.
An advanced valvetrain and a variable intake system (VIS) mean that the engine can be exploited efficiently throughout the rev range, thus promoting quick response and solid performance. At the same time, the engine is very fuel-efficient.
The valvetrain features VCT (Variable Cam Timing) and CPS (Cam Profile Switching) on the inlet side. CPS (Cam Profile Switching) means that the camshaft is designed such that the inlet valves are lifted to two different heights depending on engine speed and load.
In normal driving, with normal throttle opening and low engine revs, fuel consumption is modest at the same time as torque is sufficient to provide good driveability.
In more aggressive driving involving full throttle opening and high engine revs, the engine responds instantly to the accelerator and provides a thrust of power, both at low and at high speeds.
In principle, Cam Profile Switching creates two engines in one. We can unite widely differing demands on one and the same engine and easily meet the requirements of customers with entirely different wishes. For instance, we can equally easily satisfy customers who prioritize performance as well as those who are more interested in driving comfort and fuel economy.—Derek Crabb, Vice President Powertrain, Volvo Cars
The VIS is equipped with two throttle flap valves which adjust the intake manifold volume to suit the current driving situation. This results in a uniformly high and broad torque curve.
Through precise interplay with the flap valves we actually get three different torque curves that are integrated with one another. Consequently, we can exploit the engine’s capacity to the maximum and extract the highest possible power throughout the rev range.—Derek Crabb
Transverse mounting of the 3.2-liter engine.
The complete engine package is only 3 millimeters longer than Volvo’s five-cylinder engine, allowing for it to be mounted transversely. The engine itself cannot be made all that much smaller since the cylinder spacing and block structure are roughly the same as in a five-cylinder engine. Instead, the focus was on building the entire installation, encompassing the engine, automatic transmission and ancillaries, in as compact a package as possible. One additional condition that had to be taken into account was that the transmission would be a six-speed automatic.
The ancillary systems, such as the Power Assisted Steering Pump and Air Conditioning Compressor are placed behind the engine in the space above the gearbox. Consequently, there is no front-end drive of the ancillaries; rather they are driven via gears by the rear end of the crankshaft.
This design approach is known as READ—Rear End Ancillary Drive. The alternator is direct-driven and installed on the engine block. This solution means that the entire engine and transmission package takes up minimum space, particularly in the car’s longitudinal direction.
By designing the drive system in the form of a small gearbox with an intermediate shaft inside the driveshaft—known as a Shaft In Shaft design—it was possible to ensure a very short package. The two shafts are driven by different gears that give them different speeds (one speed for camshaft drive and one for the ancillaries).
The engine will start series production in week 13, 2006.