A 3.9L Flat-8 would offer plenty of options for Porsche.  Even if it starts with 650hp with 4 turbos, there will be enough headroom (with more boost) in such a setup to make around 1,000hp if needed.

It could also form the basis of a mean NA motor with ability to rev close to 10,000 rpm if desired (for GT3?).  Cylinders smaller than 500cc are much easier to rev than the big cylinders in the 4.0L and rumored 4.2L Flat-6 RS motors.  And there would be room to grow the displacement (which will be near max at Flat-6 4.2L).  Same cylinder size would give 5.6L in a Flat-8 with NA power at ~ 700hp if same efficiency as current RS.


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16 Cayman GT4, 73 Carrera RS 2.7 Carbon Fiber replica (1,890 lbs), 06 EVO9 with track mods. Former: 73 911S, Two 951S's, 996 C2, 993 C2, 98 Ferrari 550, 79 635CSi