Interesting story on Gizmag this morning about how Porsche has patented a new type of variable compression ration engine technology. Partnering Porsche in this venture is Hilite International, already a long-standing client at Porsche Consulting.
Variable Compression Ratio (VCR) is a prime candidate for the next big step in internal combustion engine efficiency. It is particularly suitable for turbocharged engines, and we know that all 911s will adopt turbocharged engines over the next few years, alongside the many turbocharged model variants in the Macan, Cayenne and Panamera ranges already produced by Porsche.
Compression ratio is critical to performance, and is of particular importance on turbocharged engines. Turbos work by compressing the intake charge of air and fuel before ramming it into the combustion chamber under pressure. Because a turbocharger is powered by exhaust gas, and therefore is not always running at peak boost, the amount of fuel/air mix entering the cylinder varies from low volume when the turbo is not spinning to maximum volume when the turbo is running at peak revs. Turbocharged engines must therefore run lower compression ratios, to allow that higher volume at peak boost. This costs them power.
Why use Variable Compression Ratio technology?
One way to increase the efficiency of a turbocharged engine would be to constantly adjust the compression ratio, giving higher compression off-boost, and reducing the compression as boost pressure rises, to prevent detonation. The Porsche system (top) is clever, planting the piston on an eccentric mount that is automatically adjusted by control rods, which swivel the piston up or down on the crankshaft connecting rod depending on oil pressure, thus controlling the compression ratio.
Compare this solution to the nicely engineered but complex solution developed by MCE over the last decade (above photo shared under ‘fair use’), and it is perhaps easy to imagine how this new patent might better suit volume manufacturing, delivering less risk to reliability. It is also highly licensable technology: something which Porsche has done very well from over its history. So, even if the technology never makes it into a Porsche, it could be shared commercially with a wide range of other end users.
Bravo Porsche engineering! We look forward to seeing a fully developed version of this system come to production, and to experiencing the benefits on the road.