Our friend Richard Aucocks brings us all the way from UK an interesting report on the 2011 BMW 520d Touring. The diesel engine in the 520d gives an excellent ratio of power consumption and despite its 184 horsepower, the BMW 520d offers a standard consumption of just 5.1 liters of diesel per 100 km (46.1 mpg), which corresponds to CO2 emissions of 135 grams per kilometer.
Let’s have a look.
“BMW’s latest 5 Series marks the introduction of 4-cylinder engines into the F10 platform. Until now, it’s been all 6-cylinders or V8s.
Powertrain manager Jan Kretschmer revealed what’s been keeping them busy at the launch of the 520d variant, on the debut of this September’s F11 Touring.
My, they’ve been well-occupied, it seems. ‘4 cylinder engines are always a bigger challenge for our engineers,’ he explained; even ones like this, with counter-rotating balancer shafts.
They have, as you know, a different (‘and higher’) level of NVH – noise, vibration, harshness. ‘You have to consider this before you even start with the development and installation.
‘Luckily, our Body-In-White department is able to conduct a lot of simulation work (big investment in computer technology over the past half-decade facilitates this). This means we can predefine possible weaknesses where extra stiffening may help – or, actually, stiff areas where some weakness may be beneficial!
‘They start this 5 years before the vehicle hits the road.’
Concurrently, his powertrain team will be working to provide the smoothest possible engine for eventual implementation. With the 184hp (135kW) 2.0-litre diesel, Kretschmer explained the process was one of evolution. ‘We were tasked with further refining an already high-level engine, rather than reinventing it.’
Two key development areas were prioritised here:
• Engine Mountings: ‘These must be isolated. We fit electronically driven semi-hydraulic engine mounts, with 2 characteristics. At idle and low rpm, they are ‘weaker’, to absorb low-level vibration. When driving, there are fewer engine vibrations, so we stiffen them to improve handling.’”
To learn more about Fluctuating Torque and other technical detail, read the full article.