Porsche's new exhaust has saved the 9,000rpm flat-six

By topgear, 11 May 2019

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Hurrah! 911 Speedster's new exhaust tech helps future GT3s and GT4s avoid turbos

Porsche launched the 911 Speedster this week, effectively a swansong for the old-gen 911 and with the 991.2 GT3’s howling 4.0-litre flat-six sitting pride of place in its rump.

(Click HERE for a brief pictorial history of Porsche Speedsters)

It’s a stupendous engine, revving to 9,000rpm and making one of the very greatest noises on earth as it does so. As a reminder that naturally aspirated engines are often more fun than turbos, it’s as stark as they come.

Happily, Andreas Preuninger -; head of Porsche’s GT-badged cars -; all but confirmed this isn’t the engine’s swansong, with much of the thanks going to a clever new exhaust system. It incorporates a particulate filter, to lower the car’s emissions, but thanks to the fastidiousness of Porsche’s engineers it’s somehow gained 10bhp and lost 10kg, too.

'This is what happens when you push very good engineers to the limit,' Preuninger tells us. 'It has very thin steel sheet soldering which is super light, and losing 10 kilos at the back end of the car -; down low -; is something you really feel.

'You don’t lose a lot of sound either. This car is a little more well behaved, but it has a more cultured sound, which is okay for a Speedster. It fits the times we're living in at the moment a little better.

'The valving in the exhaust is electrically controlled, so it’s continuously moving. We are the only ones with an electric system that can take the heat of an exhaust. If you control the flaps mechanically the sports exhaust is either on or off.'

So, the soundtrack is still pretty exceptional, and friendlier emissions effectively futureproof this engine, too. So surely the next GT3 and GT4 models can duck out of turbocharging, too.

'We have saved this beautiful creature for the future,' says Preuninger, who wouldn’t be drawn on where we’ll actually see the 4.0-litre flat-six next. 'We are trying to keep the flame alive as long as possible. We think the high-revving naturally aspirated engine is an amazing thing that needs saving.'

We couldn’t agree more…

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