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Rear Engine vs Mid Engine… and Santa’s Beard

Image Courtesy Motorsport.com - 2017 Porsche RSR

Last week Porsche unveiled its 2017 911 RSR at the L.A Auto Show. Looking at the picture it’s obvious to even “non-petrol heads” that it’s a track car. That rear wing would make a Boeing blush and that rear diffuser would feel right at home on the front of a piece of earth moving equipment.

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The most interesting thing about this car isn’t its exaggerated body parts, it’s not the transmission, or carbon fibre body, or its collision avoidance tech, it’s all about the engine, specifically its position.

The iconic silhouette and the rear-mounted engine are what make a 911 a 911. Moving the engine would be like Santa Claus sporting a freshly shaved face this Christmas. It is like hanging the presents up on the tree and laying out the ornaments and tinsel at the base of it instead, it all still works but it’s all kinda backwards.

Could we see 911’s of the future sport a mid-mounted engine like their RSR sibling? What difference does it make?

The difference between a rear-engine and a mid-engine car for dummies, for dummies.

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Rear mounted engines sit behind the rear axle (like in a 911), the rear axle being the ‘connection’ between the rear wheels. This is great for getting off the line as the weight sits over the rear tyres assisting them with grip (part of the reason a Turbo S launches off the line so quickly).

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During braking weight shifts forward but having that weight over the rear tyres means that breaking force is shared more evenly between all wheels resulting in shorter stopping distances.

The downside is best explained by imagining throwing darts in a pub, now imagine turning the dart around and throwing it with the heavy end at the back, the heavy end is going to try swing round to the front.

The same happens in a rear engine vehicle, meaning the 911 has a tendency to oversteer, which is what’s generally happening when you see Clarkson smoking the tyres of a supercar around a corner.

That looks really cool but is far harder to correct than understeer and can land you in some trouble and by some trouble I mean a ditch or a pavement. Not that you can’t crash a front engine car, front engine cars are just easier to manage in the event of overstepping the mark.

Now the reason you would mount an engine towards the middle of the car is almost purely due to weight distribution and its effect on handling. The nearer the balance of the weight is to the centre of the car, the more agile it should be, think of the ease with which a spinning top rotates, be in clockwise or anti-clockwise. The downside being the loss of the advantages mentioned above and also that millions of 911 fans will shit themselves at the thought.

Porsche have refined this rear engine package over decades and what we have now are very balanced, very proficient sports cars. Porsche Fanboy or not, you can’t argue, they are mechanically impressive.

The question is, have Porsche pushed the limitations of their existing set-up to the edge of what’s possible? Is the only way forward to shift the engine position? Is it worth changing the character of an icon in the pursuit of what really, a track time?

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Yes, Santa could take years off his appearance if he shaved, and yes life would be easier for him without that cookie crumb collector on his face, but he wouldn’t be him, he’d be an intruder wearing red that happens to also give presents. So a very generous intruder who wears red. Which actually doesn’t actually sound that bad, let’s see what happens.

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