- Porsche has secured a patent for a 6-stroke engine
- Except for the early Saabs, most gasoline engines in cars today operate on a 4-stroke cycle
- Porsche’s new 6-stroke patent suggests a potential for increased engine power
If you don’t own an early Saab, it’s likely that your vehicle features a 4-stroke engine. However, Porsche is investigating whether a greater number of strokes could yield better results.
The car manufacturer has submitted a patent application titled “Method for a Combustion Machine With Two Times Three Strokes,” effectively referring to a 6-stroke engine. The patent was brought to attention by AutoGuide and was published by the United States Patent and Trademark Office (USPTO) on September 12, following its submission by Porsche in February.
Porsche 6-stroke engine patent image
In this discussion, a “stroke” refers to the vertical movement of a piston within a cylinder. A 4-stroke engine requires four of these movements (or two crankshaft rotations) to complete a power cycle, which includes drawing in air and fuel, compressing them, igniting them (the power stroke), and allowing exhaust. Conversely, a 2-stroke engine, like those found in lawnmowers, accomplishes this with just one revolution of the crankshaft.
The engine design outlined in Porsche’s patent filing introduces an additional compression and power stroke by adjusting the stroke length. This innovation is facilitated by a series of eccentric gears that enable the pistons’ bottom-dead-center to be deeper, allowing for extra strokes. This design permits the opening of scavenging ports, which draw in extra air, followed by further fuel injection and combustion.
Porsche 6-stroke engine patent image
The primary aim behind this design appears to be increasing power output, as the 6-stroke engine features two power strokes compared to the single power stroke of a traditional 4-stroke engine. This translates to a power stroke occurring every third crankshaft revolution instead of every fourth, as is the case with a conventional 4-stroke engine.
However, a significant concern remains whether this arrangement can comply with existing emissions standards. This raises the possibility that, like many patents, this engine design may not transition into mass production. Nonetheless, several engine technologies once deemed impractical for regular use—such as variable compression ratios—have successfully reached the production stage as manufacturers continue to find ways to reduce emissions. Thus, there may still be potential for this innovation.
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