Said by Porsche to "cast aside all constraints of the FIA GT3 regulations", the 911 GT3 R-based sports car is destined for a 77-unit production run after its planned presentation on 28 October at Rennsport Reunion - one of the world's largest gatherings of Porsche enthusiasts.
Two versions of the 1240kg racer are available with different specifications based on racetrack noise regulations - an unsilenced variant and a silenced version, the latter available in two guises and with catalytic converters.
Power comes from the same 4.2-litre six-cylinder boxer engine as that used by the 911 GT3 R, but a host of efficiency tweaks boost its power from 557bhp to 611bhp, its redline to 9400rpm, and its top speed from 184mph to 196mph.
An output of 148bhp per litre is "a record for a naturally aspirated engine of a GT racing car", Porsche says. Power is sent to the rear wheels via a six-speed sequential gearbox.
The engine itself has been designed to run on bi-ethanol fuels and e-fuels to make it as carbon neutral as possible in operation. However, it can also run on conventional unleaded.
Thomas Luadenbach, vice president of Porsche motorsport, said: "The new Porsche 911 GT3 R Rennsport offers the experience of driving a 911-based racing car in what is probably the most primal form. It gives you goosebumps whenever you look at it and combines the finest motorsport technology with a design language that is typical of Porsche."
Designed by Grant Larson and Thorsten Klein of Porsche Style, the Rennsport is said to share only its bonnet and roof with the donor car.