r/cars • u/Juicyjackson • 1d ago
Six Education: Inside Porsche's Six-Stroke-Engine Patent
https://www.caranddriver.com/news/a63266626/porsche-six-stroke-engine-patent-details/16
u/orhantemerrut 2024 Hyundai Elantra N 1d ago
Interesting, and of course puzzling. The second compression/stroke seems to happen along such a short amount of displacement that it's difficult to surmise its practical function. The first thing that came to my mind is to compensate for turbo lag as the fourth stroke contains both exhaust outtake and air intake. That small power might help with the lag... maybe?
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u/Gonnaragretthis 1d ago
IIRC, the 4th stroke allows for more complete combustion and helps reduce emissions?
With regulations tightening up, especially in Germany, I see this as a potential play for Porsche to keep ICE alive awhile longer.
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u/Snazzy21 1d ago
They should eliminate the intake valves, and use the intake port at BDC to simultaneously push exhaust gasses from the exhaust valve at the top while replenishing fresh air from below with the help of a supercharger, then close the exhaust valve and inject fuel and ignite for every rotation of the crankshaft.
Makes more power with the same or less weight, is more resistant to carbon build up than traditional valved DI engines, and fuel is added directly at the end-no chance of scavenging.
So basically a proven 2 stroke diesel that uses gasoline
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u/nguyenm '14 Civic EX 1d ago
That'd require mandatory forced induction for the scavenging effect, as well as a rather lengthy stroke to bore ratio to have somewhat of an efficient combustion process.
Furthermore, although I may be wrong on this one, most application of 2-stroke diesels are not subject to emissions regulations the same ways automobiles are. So it can forgo a lot of emissions equipment that would reduce the reliability of such engines.
There's the experimental opposed-piston engine that was featured on Engineering Explained but no commercial application yet, only a military contract.
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u/LordofSpheres 18h ago
It's already going to require forced induction because they're already using the ports for intake and prior to combustion - and because the intake ports are so low, there won't be time to use blowdown to equalize pressures.
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u/varezhka11 1d ago
It looks like a complex engineering for complexity's sake, just how Germans like it. Similar to expensive mechanical watches or Nissan's VC turbo. No thank you.