Porsche's idea for a six-stroke internal combustion engine

Engine concept & combustion strategy

• Many try to infer how the six-stroke works: intake → compression → power → compression → power → exhaust, with two different TDC/BDC positions via an eccentric crank “ring.”
• Hypotheses for the second power stroke:
  • First burn is very lean, leaving oxygen and partially burnt products to be recompressed and reburned.
  • Extra air (and possibly fuel) is introduced through scavenging ports between the two BDCs, making the second phase like a mini uniflow 2‑stroke.
  • Alternative idea: inject water into hot exhaust for an extra expansion stroke (referencing older six‑stroke concepts), though that’s not clearly what Porsche is doing.
• One commenter reads the patent and lays out the exact six strokes, confirming: first power stroke uses a longer expansion path; second compression uses a higher effective compression ratio.
• Overall goal is seen as Atkinson/Miller‑like: greater expansion than compression to extract more energy from a charge.

Efficiency vs power and Porsche’s priorities

• Repeated debate: does “efficiency” here mean more power from same fuel, or less fuel for same power?
• Several argue Porsche historically uses efficiency gains to make higher‑performance cars, not economy cars, though they do care about fuel use as a constraint (emissions, range, marketing).
• Discussion of Cayenne/Macan: disagreement over whether base models are just luxury family SUVs or fundamentally high‑performance, overengineered platforms repurposed as family cars.

Mechanical complexity and feasibility

• Multiple notes that modern ICEs already have very complex valvetrains (variable timing/lift, multiple cams).
• Porsche engines are seen as especially complex and expensive to rebuild; this six‑stroke crank mechanism adds yet more high‑precision loaded parts.
• Concern that such complexity limits down‑market adoption, but Porsche’s clientele is less sensitive.

ICE vs EV and market trajectory

• Some see investing in advanced ICE as like optimizing OS/2 in the Windows era; others argue ICE will persist for decades (long‑distance, racing, aviation, rural use).
• European data cited showing EV sales slowing, blamed mostly on price and infrastructure.
• Counter‑arguments: battery tech and charging will improve; majority of people could use EVs within a few years, though a minority will remain ICE‑dependent.

Driving experience and enthusiast culture

• Strong theme: sports‑car enthusiasts value light weight, handling, manual gearboxes, and engine sound more than 0–60 times.
• EVs praised for straight‑line performance and some Nürburgring times, but criticized for weight and “sterile” feel.
• Others claim attitude is shifting and electric or hybrid supercars are increasingly accepted, though many report ICE still dominates enthusiast meets.

Alternative engine ideas referenced

• Mentions of Miller/Budack, Atkinson, variable compression (Nissan), free‑piston generators, camless valves, rotary/vaned engines, and earlier six‑stroke concepts (Crower water‑injection, Ilmor/“5‑stroke”).