Porsche seems determined to keep combustion alive.
Porsche is at it again, and by 'it,' we mean refining the concept of turbocharging even further. CarBuzz discovered a new patent published by the German Patent and Trade Mark Office, and it outlines Porsche's latest design for increasing turbocharger performance and efficiency by – in a way – recirculating excess boost pressure and exhaust gases that would otherwise be wasted. But not in the way we already know of.
In a nutshell, the novel system diverts some of the exhaust gas of the engine toward a secondary turbocharger of sorts without impeding the performance of the main turbocharger. It requires a little bit of background information to convey how this works properly, so let's dig in.
The Premise
To understand how this invention is different, we need to understand how existing turbocharger systems work, so give our comprehensive explainer a read if you're new to forced induction. If not, keep reading.
In January last year, CarBuzz discovered a separate turbocharger design wherein the shaft of the compressor and exhaust turbines is connected to a generator feeding an electric motor that redirects energy back to the compressor again, using stored electrical energy harvested from exhaust gases to effectively eliminate turbo lag. Roughly seven months after we discovered the invention, Porsche formally announced its development along with other similar ideas.
This new invention builds on the idea of harvesting energy from the turbocharger, but instead of the turbine shaft powering a generator, this one sees the exhaust gases split into two channels. One powers the conventional turbocharger that compresses intake charge to the engine, while the other channel feeds what is effectively another (likely much smaller) turbocharger, but one that does not directly feed the powertrain – at least not all the time.
Dividing Turbo Gases
Gases leaving the cylinder head after combustion are divided by a two-way channel; one channel feeds the normal turbo and the other our secondary compressor. Instead of this pushing dense air back through the cycle, the secondary 'turbo' is coupled to a planetary gear affixed to an energy sink. Therefore, harvested energy can either be converted into stored electrical energy or used immediately.
Basically, you have two turbo-like systems in parallel. One harvests and deploys energy traditionally, while the other can either save it or reroute it.
On the one hand, the energy can be used to “operate the charge air cooler.” As a fixed piece of hardware, the intercooler is always working. Thus, it appears that Porsche means to restrict or increase flow to the cooler as needed, manipulating intake charge temperatures and boost pressures.
Therefore, if the traditional turbo is providing sufficient boost, the secondary 'turbo' pulls back without an overall performance drop. On the other hand, if the cylinders experience a drop in compression, this could compensate by increasing the pressure fed from the secondary turbo.
Key Points
The main takeaways of this technology are as follows. Porsche has found a way to manipulate boost without affecting the primary turbocharger's wastegate and can therefore maximize turbocharger efficiency. This system suggests that the turbo can be made to waste almost no energy (besides through heat).
If the turbo boost spikes, the engine is not hit with a sudden wave of connecting rod-bending torque. When the turbo is struggling somewhat to make sufficient boost, the secondary 'turbo' that has been saving all that wasted energy helps it along by increasing the flow to the intake plenum. This idea could be integrated with the other patent we cited at the outset for even more astonishing throttle response and efficiency.
Porsche can use a bigger turbo and make it feel less laggy. Or, Porsche can use a smaller turbo and ensure it always provides more performance than a comparably sized turbo of traditional design. It also means something like a stock Porsche 911 Turbo can potentially tackle Pikes Peak without altitude-specific tuning.
Finally, Porsche can harvest even more energy from a turbo without much more complexity and without a spiky (or excessively flat) torque curve. That bodes well for the feel of future turbo engines from Stuttgart but also for hybrid offerings. With an electric component of sorts, Porsche might be able to make the inevitable electrified 911 feel much like the great naturally aspirated flat-sixes of old and avoid incurring hefty weight penalties.
Porsche has promised that the 911 hybrid will not be a plug-in, which means it will use electrification for greater performance more than for better efficiency. Tech like this may potentially satisfy the legislative need for an electrified 911 without sacrificing the driving experience that characterizes the car.
The potential applications are huge, and we applaud Porsche for continuing to refine the combustion engine in the face of so much uncertainty over its long-term future.
Keyword: Porsche Will Save The Sports Car With New Turbo Tech