porsche mid-engined 911rsr

2y ago


I have been a member of the Porsche Owners Club GB on two separate occasions in the last 20-odd years. The reason I let my membership lapse each time is because of the purist approach by some of the members. You know the types - the ones that have a nasally voice and often approach your car with their arms behind their back whilst wearing a frown. It's these people that really do not want evolution. They hated the 964 back in period, but now they love them. They have only just stopped having therapy from when the 996 was launched with WATER cooling the engine. And it's these people that were very quick to the Porsche forums when Porsche Motorsport announced the new 911 RSR.

New rear aero on the 911 is the real reason the engine has moved forward.

"It's a Cayman in disguise." Well, no it's not actually. Yes, it's true that Porsche have rotated the engine through 180° to make the new RSR mid-engined though. But we should ask ourselves why they have done that. It's no secret that a mid-engined sportscar is better balanced than one with a weighty lump slung out over the rear axle. But let's be honest, the magicians at Weissach have long understood how to get the best from their cars with this apparent 'disability'. In 2016 there weren't any Factory 911's running in WEC or Le Mans, but in 2015 they did very well...

What changed in 2016 was the rulings for aero. And some cars really benefitted from this change. The biggest winner was the beautiful Ford GT. This car alone re-wrote the rulebook - it's effectively a prototype GT car. They designed the racecar at the same time as the worked on the road car, whereas all other manufacturers are working on road car designs as the starting point. The Ford was hit with success ballast at various races, but left to run how it can then it would be almost unbeatable. The next two 'best' GT race cars in 2016 were the Ferrari 488 and Aston V12. The Ferrari is always a formidable package, but suddenly the ageing Aston was competitive again. And the reason why these three led the pack was aero. Specifically the aero at the rear. Take a look at the pics below:

And there we have the real reason that Porsche have HAD to rotate the engine through 180°. Yes it will aid balance - but the car will lose some of that traction pulling out of corners that actually helped the 911. So there's a trade off. But the big gain is the rear aero - those enormous rear diffusers can now go on a 911 because the engine isn't in the way anymore!

The key role of the diffuser on a modern racecar is to accelerate the flow of air under the car, creating an area of low pressure, thus increasing downforce.

Racecar Engineering

New rear diffuser on the 911. It's HUGE.

The diffuser increases in volume along its length, creating a void that has to be filled by the air passing under the body. This venturi effect means that the flow is accelerated through the throat of the diffuser, creating the desired low pressure, then gradually returned to the same velocity at which it joined the wake. This is often referred to a aerodynamic grip, and that will be new to the Factory Porsche GT drivers in 2017.

So there you have it. Some of the naysayers in the Porsche Club think Porsche have sold out and created a 'Cayman GT4 RSR', but they haven't. They've done what they needed to do to make sure they stay competitive when the rules allow such monstrous rear diffusers. And that's why the next GT3 or GT3 RS will NOT be mid-engined. They don't need that rear aero and therefore the 911 road cars from Weissach will remain rear engined. The Porsche Club owners will be happy.