Porsche has filed a new patent with the German Patent and Trade Mark Office that seeks to improve the acoustic quality of the turbocharged engine.
A naturally aspirated engine sucks air into the engine through an air filter and intake system that flows directly into the cylinder head’s inlet ports, through the intake valves, and into the combustion chamber. Once the mix of air and fuel has been burnt, it exits through the exhaust valves, out the cylinder head, and into an exhaust system. With a turbocharged engine, this air flows from the intake, through a compressor into a charge air cooler, and then into the intake ports of the head. On the other side, the exhaust turbine of the turbocharger comes into play. Each of these additional steps muffles the usual intake and exhaust sounds. Porsche’s patent aims to remove this muffling effect through a novel sound device.
How It Works
Artificial sounds are noticeable as such, so Porsche has tried to improve the aural quality of turbocharged engines in an authentic manner. The patent describes a new component that is added downstream of the charge air cooler. This cannot restrict the flow of air, so it simply allows the air to flow through a port. But as the air moves from the inlet section of this component and out toward the intake manifold, it also moves over a membrane. This so-called “flow guide surface” can be conical or hyperboloid in shape, which means that it can magnify sound through a trumpet-like design.
Various fins and restrictors/openings are used to modify the sound as it is channelled toward the firewall between the cabin and engine bay. Elastic bellows connecting this sound device to the engine help to ensure that its carefully designed noise is not diluted by the movements of the latter.
Why It Matters
Porsche has used a mid-rear-engine vehicle like a 911 to describe this patent and repeatedly notes that its only purpose is to improve the enjoyment of driving for keen enthusiasts who value the aural quality of their driving experience. A mid-engine design is probably best for keeping the sound as undiluted as possible, as the intakes are closest to the cabin.
Porsche also notes that a boxer or V engine layout is best, which suggests that this sound device could manipulate sonic waves in a similar fashion to an equal-length exhaust setup. How effectively this system would mimic an unassisted engine can only be judged once it is heard in the real world, but it’s encouraging to know that it exists and that it would be hardware-based. The GT3 is still forced induction-free, but with ever-tightening emissions regulations, that may soon change. Porsche wants to have the answer to an authentically visceral turbocharged aural experience before it is asked the question of how to keep one of the most engaging cars on the planet as such.
