There's no chance of a future flat eight engine for the Porsche 911, despite the prospect having been seriously considered.

The flat six layout is effectively constrained at 4.0 litres because of issues with the size of components that would be needed for a larger-capacity version.

Heinz-Jakob Neusser, who was previously powertrain boss at the Volkswagen Group, said a flat eight would have to be 5.0 litres in capacity and was “probably too big”.

Neusser said: “We have been in the pre-development phase with an engine like this, but we never did it.”

He added that the future flat six Porsche engines would still be able to run to high revs. “Moving to turbocharging is not a problem; it will give us more freedom [in future engine design],” he said.

A facelifted version of the 911 is due to launch at the Frankfurt motor show later this year, and will come to market with a range of new engines ahead of the all-new model coming in 2018.

Among the changes scheduled for the facelift is the introduction of a new range of turbocharged six-cylinder, horizontally opposed engines to replace today's naturally aspirated units.

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