LA Auto Show 2016: Sneak Peek – Porsche 911 RSR
So what’s the huge sacrilegious change? This so-called 911 RSR is MID-ENGINE. Yup, no more engine hanging out the ass-end of the car messing up the polar moment of inertia and taking over four decades of tweaking and modern 4-wheel steering to tame the back-end. Phew, long sentence. But, the polar moment of inertia and weight distribution was not the reason for going mid-engine in the lead GT race car from Porsche.
This massive rear diffuser is the reason for the change to mid-engine in the 911 RSR. You see, Porsche got its butt whooped last year in GT racing because of the fundamental aerodynamic disadvantage of the rear-engine layout. The engine sat exactly where a rear diffuser wanted to live in order to maximize rear aerodynamic performance. The front and mid-engine layouts of the Ford GT, Ferrari 488, Corvette, and BMW M6 allowed for generous rear diffusers to maximize downforce while minimizing drag. On a side note, check out the rear tow hook which swings under the body. I wonder if it’s for aero reasons or just so no mechanic runs into it while running around the rear of the car.
With the mid-engine layout, you can see the diffuser now begins much further ahead than was possible before with the rear mounted engine. I’m guessing it’s somewhere in front of the rear axle line. There’s also this big fence to try to keep the dirty air coming off the rear tires from screwing with the airflow in the diffuser. The fasteners used to attach the diffuser are all round or flush head to reduce drag. Every little bit counts!
That’s a shiny, rear transmission case machined from billet. On the right side of it, the vertical rectangular box with ribs might be the transmission fluid cooler using coolant. You can also see the rear tubular structure, which I’m guessing makes up a rear subframe structure.
Each bank of the engine dumps out a muffler on top of the diffuser. The car must have been extremely loud to actually use a muffler on a race car. The exhaust tip has a v-band joint to allow for quick removal from the muffler. This is probably for when the diffuser is taken off to allow for easier transport. Heat shielding is all around the exhaust to protect the carbon fiber diffuser. The steel cable used to support the weight and downforce of the diffuser is a trick looking component itself.
The front tow hook also swings into the bumper. They even have rubber to seal off the slot. I’m guessing both of these features are to reduce aero drag. The tow hook folded in probably also saves a few bruised shins.