Porsche Is Keeping Combustion Alive With a New Water-Injection System

https://www.autoblog.com/news/porsche-is-keeping-combustion-alive-with-a-new-water-injection-system

Spray Water Into Your Engine For More Power

While Oldsmobile, Saab, and even BMW have dabbled in water-injection systems for production cars over the years, Porsche has been quietly filing patents that indicate a strong interest in refining this technology at Stuttgart. For the uninitiated, water injection is a method of cooling the intake charge and combustion chamber by introducing a fine mist of water (or a water-methanol mix) into the intake tract. As the water vaporises and turns to steam, it absorbs heat from its surroundings, thus cooling intake and combustion temperatures. Cooler air is denser and nets more power, and a cooler combustion chamber is less prone to knocking — allowing for higher boost pressures and aggressive ignition timing without the risk of detonation. 

This technology has been around for a while, first seen in mid-20th-century high-boost piston aircraft engines, but its use in land vehicles has been limited and mostly confined to motorsports applications and the performance tuning world. Oldsmobile tried it out in their 1962 Jetfire, the world’s first turbocharged production car, Saab tried it in the late ‘70s and early ’80s, while the system was most recently seen on the short-lived 2015 BMW M4 GTS. While other manufacturers seem to have moved on, it looks like Porsche is intent on making the tech truly production-ready.

Porsche Still Focused on Internal Combustion

Now, at a time when most manufacturers are turning the attention of their R&D departments towards battery and charging technology, Porsche engineers are still working behind the scenes to drive innovation in the internal combustion space. Earlier this year, the German manufacturer filed a patent for a new water injection system, and now another patent has emerged, this one describing a method to diagnose and test the system. 

The Problem With Water Injection  

Porsche’s latest patent focuses on a method to monitor pressure in the system and ensure that the appropriate amount of water is introduced into each cylinder at any given point. Being able to precisely meter the correct amount of water into each cylinder is extremely important; too little leads to higher engine temperatures, a tendency to knock, and reduced power, while too much water can damage engine or intake components due to the water hammer effect, or worse, result in excess liquid entering a cylinder, leading to hydrolock and catastrophic engine failure. 

All water-injection systems so far can only correctly meter flow when the engine is at high rpm and under heavy loads. This means that a reliable diagnosis can only be carried out under these conditions, with the car being driven and accelerating hard. Porsche, on the other hand, is working on simulating these conditions on a stationary vehicle to enable on-demand diagnostics of the water injection system and its components. 

How Porsche’s System Works

The patent documents detail a rear-engined car with a hybrid powertrain equipped with all the necessary hardware for a water-injection cooling system. This includes a water tank with a pump unit leading to a pressurised rail and injectors meant to spray a fine mist of water into each combustion chamber. The patent drawings also feature a diagnostic device and an external workshop tester. 

The on-board diagnostic device uses the hybrid powertrain’s electric motors to momentarily increase engine speed and manage the load on the engine against the torque from the motors. This artificially simulates the conditions necessary to accurately diagnose issues or spot inconsistencies within the water-injection system, all with the car stationary in the workshop or service bay. 

The patent also highlights that the increase in engine speed required to carry out this test can be achieved automatically by the diagnostic device, or manually by a technician depressing the accelerator pedal. The system can then accurately diagnose the water-injection system by shifting the load point as necessary, and spraying water through the injectors at the right time to mimic real-world driving conditions. The results of the diagnosis and errors, if any, are then stored and displayed in the external workshop tester. 

The Bottom Line

Despite the challenges of incorporating water-injection systems today, chief among them the need for a refillable water tank that still requires manual intervention and complicates emissions compliance, Porsche’s persistence shows the brand isn’t ready to let combustion fade quietly into history. Instead, Stuttgart is pushing the boundaries of what a modern ICE can do, using clever diagnostics and hybrid assistance to make technologies like water injection genuinely viable. In an era dominated by electrification, Porsche’s latest patents prove there’s still meaningful innovation left in the world of pistons and boost.

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November 23, 2025 at 03:55PM