Technology explained Porsche 911 GT3 RS 991 magnesium roof

Technology explained Porsche 911 GT3 RS 991 magnesium roof

Use of a new, lightweight, yet strong material broke new ground for Porsche in 2015

Porsche once again broke new ground upon the release of its 991.1 GT3 RS in 2015, its magnesium roof meaning Porsche was the first manufacturer to feature a magnesium body panel on a production sports car.

Porsche has used magnesium on its 911 sports car before of course, namely for the crank case on its earliest models in the 1960s but, as we’ll see, the decision to produce external body panels was clearly thought through, and possible thanks to 21st century manufacturing practises.

There are many advantages to using magnesium in this way. The alloy is 33 per cent lighter than aluminium, yet boasts a comparable strength-to-weight ratio with the latter. It is for this reason Porsche used magnesium for the 991 Rennsport’s roof, significantly lowering its centre of gravity – a shrewd move when it comes to the handling credentials of any sports car. Porsche went further in refining the use of the alloy, too. Due to the roof being a key panel in terms of crash safety and, seeing as it was deployed on a sports car with track use in mind, Porsche incorporated two ridges running longitudinally down the panel’s entirety. Giving what we now know as a ‘double bubble’ appearance (the look has been replicated on the 911 R and subsequent 991.2 GT3 RS and GT2 RS), the ridges are there chiefly to serve a purpose of increased strengthening. There are also acoustic advantages to be had, as magnesium parts can be tuned to reduce vibration and overall noise, which is key in a vehicle that is otherwise stripped of sound insulation while running huge 325-section rear tyres.

There are also manufacturing advantages too, as magnesium alloy is quicker to produce thanks to a longer die life and faster solidification when setting – handy when Porsche ended up producing many thousands of 991.1 GT3 RS over just two model years!

There are drawbacks to the use of magnesium in automotive, namely the high manufacturing cost, which is why a magnesium roof is reserved currently for Porsche GT cars only (magnesium wheels are also offered as part of the optional Weissach Pack on the 991.2 GT3 RS and GT2 RS). The use of magnesium as a new material on automotive body parts has been a pioneering move, and we can expect to see a greater use of it on 911s of all variations going forward as manufacturers look to increase the efficiency of its vehicles by saving weight. 

Chris Rees

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