2019 Porsche 911 RSR revealed

The multi-million-dollar 2019 Porsche 911 RSR wide-body GTE race car has been revealed at the Goodwood Festival of Speed in England.

Powered by a bigger, more potent 4.2-litre six-cylinder boxer engine, Porsche is serious about defending its World Endurance Championship crown.

With less than 10 of these exotic race cars expected to be built each year – only select buyers are invited to purchase the car – the updated German apex-predator's bigger, more powerful 4194cc naturally-aspirated (non-turbo) horizontally-opposed six-cylinder powerplant is the "largest ever boxer engine to be mounted in a Porsche 911 ex-works," according to the German sports car brand.

Despite the balance of performance (BoP) regulations that may have an effect on its ultimate power output, Porsche says the new engine will deliver improved driveability across a wider rev-band than its precursor.

The updated engine replaces the high-revving 4.0-litre donk of its predecessor and the boxer engine is once again located in front of the rear axle, or mid-engine.

When the previous Porsche 911 RSR made its debut in late 2016 it was the first time Porsche had flipped the 911's engine from rear-mount to mid-mount.

Regular Porsche 911 models are not about to make the switch to mid-engine machines, according to Porsche insiders.

Engine power is fed through a lighter, more rigid, faster-shifting sequential six-speed constant-mesh gearbox, which hangs aft of the rear wheels, and total output of 378kW (515hp), slightly more than its predecessor.

Reworked exhaust plumping sees a pair of side pipes exiting in front of the rear wheels, which improves aerodynamics by making room for an optimised rear diffuser.

Other changes to the GTE race car include a reworked interior to improve driver comfort in endurance races, while safety systems such as the roll cage and collision warning system have been upgraded.

It runs 390mm steel disc brakes up front with one-piece aluminium six-piston racing callipers with quick release coupling and brake cooling ducts. The rear brake rotors are 355mm in diameter, worked over by one-piece aluminium four-piston racing calipers.

Footwear comprises 18-inch forged alloy wheels, 12.5-inches wide at the front and 13-inches wide at the back, all shod with Michelin slicks.

With its various carbon-fibre body panels, the 911 RSR weighs just 1245kg and Porsche expects the new 911 RSR model will defend its FIA World Endurance Championship (WEC) drivers' and manufacturers' crowns in the GTE class.

A pair of factory Porsche 911 RSR race cars will make their race debut at the at the season-opening round of the FIA World Endurance Championship at Silverstone on 1 September, as part of the 2019/2020 WEC season.

The car will not be offered in Australia as there are no GTE races here.

Customer teams will take delivery of their Porsche 911 RSRs for the 2020/2021 WEC race season.

"Since 2017 the 911 RSR has yielded us more than 20 class wins in the world championship as well as at long-distance series in North America and Europe. Our job in the development was to make a very good car even better," said Fritz Enzinger, Porsche Motorsport vice president.

"Our engineers noticed room for improvement in a number of areas," explained Pascal Zurlinden, director of GT Factory Motorsport.

"We have made significant progress in the development of our car for the next three-year homologation period, especially in the complex areas of driveability, efficiency, durability and serviceability.

"Ninety-five percent of the car is new. The only components that we’ve kept unchanged from the predecessor are the headlights, brake system, clutch, driver's seat and parts of the suspension. Tests so far have run excellently. We're already looking forward to the first races of the 2019/2020 FIA WEC season," said Zurlinden.