5 Reasons The Porsche 718 Boxster Went To Turbo Four-Pot Power

We all accept downsizing as an inevitability, but why exactly did the Boxster's engine size reduce, and why did Porsche choose a four-cylinder flat-four specifically? We chatted to 718 Boxster powertrain chief Matthias Hofstetter to find out more

Remind me later

Emissions

Porsche - 5 Reasons The Porsche 718 Boxster Went To Turbo Four-Pot Power - General

Let’s start with the blindingly obvious. Manufacturers are under increasing pressure to lower emissions and raise fuel economy, and as Matthias Hofstetter rightly points out, “downsizing is one of the most economical things to do.” On paper at least, it’s done the trick: the standard 718 Boxster is up by 5.1mpg to 40.9mpg, and the 2.5-litre in the S gets a 4.3mpg bump to 38.7mpg, with emissions down for both.

Packaging

Porsche - 5 Reasons The Porsche 718 Boxster Went To Turbo Four-Pot Power - General

‘Ah,’ I hear you say. ‘But why not stick in the downsized 3.0-litre flat-six from the 911 Carrera?’ And you’d have a point: a detuned version would still give efficiency benefits, while retaining the Porsche flat-six noise we know and love. But there’s a rather big stumbling block: it won’t fit without extensive changes to the car.

“We have the same engine compartment as in the 981,” Hofstetter explains. “If we had gone for a six-cylinder engine, we would have had to build a completely different car, and it wouldn’t have looked like a Boxster anymore.” Not only that, but it would have been a lot more expensive to develop, particularly considering this is supposed to be a mid-life refresh rather than a whole new car.

It gives the 911 a unique edge

Porsche - 5 Reasons The Porsche 718 Boxster Went To Turbo Four-Pot Power - General

While Porsche hasn’t said this was its intention, the four-cylinder switch for the new Boxster has - from a model positioning point of view - a rather happy side effect. “Now we have a situation where we have a large gap between the Boxster and the 911: they are not so close together because of the engine,” Hofstetter tells us.

The same applies to the incoming 718 Cayman, which apart from the lack of folding roof, will be mechanically identical to the Boxster. Once that happens, flat-six engines will be - sadly - reserved only for the 911, making it seem a little more special than it used to.

However, it’s not quite panned out as brilliantly as Porsche would have you believe. After all, the fastest Boxster S (with PDK and Sport Chrono) has an identical 0-62mph time to the fastest 911 Carrera. And without the complicated folding roof, the 718 Cayman could be faster still….

Flat-four history

Porsche - 5 Reasons The Porsche 718 Boxster Went To Turbo Four-Pot Power - General

While we’ve come to think of a howling flat-six to be the signature sound of a Porsche, it’s easy to forget that once upon a time, it was all about less sonorous flat-fours. And that’s something Porsche decided to reference in the Boxster’s name. “If there is now a change from six-cylinders to four, we should reference to the old cars, because this is the chance to do it. The old four-cylinder boxer cars have been successful, and we’re proud of this,” Porsche PR boss Thomas Haag explains.

As one or two of you pointed out when our review went live, reviving the 914 name would have been a great fit, but it’s clear Porsche was aiming a little higher than the more humble sports car of the 70s and 80s, deciding instead to go for ‘718’ to reference the 50s/60s racing car of the same name.

I’m still not hugely keen on the idea as it does smack a little of desperation and I can’t help but think everyone will just shorten to ‘Boxster’. Interestingly though, Haag predicts the opposite: “most probably in the future they [owners] will say ‘it’s a 718’, ‘what kind of 718 do you have?’ ‘Oh mine is a Cayman’ or ‘mine is a Boxster.’” It’ll be interesting to see who’s right…

Power

Porsche - 5 Reasons The Porsche 718 Boxster Went To Turbo Four-Pot Power - General

It’s important to note that this wasn’t just about reducing emissions, it was also about increasing power while Porsche was at it. And doing so without just adding displacement or dumping in something enormously expensive and complex like the engine from a 911 GT3 (technically possible but not terribly feasible, I’m afraid) just isn’t going to work. So, that leaves turbocharging.

“If we didn’t make this decision [turbocharging], we would lose each [group] test concerning acceleration and things like that,” Hofstetter explains. A dinky turbo six-pot would have been nice but wasn’t chosen because “it makes no sense to build a six-cylinder 2.0-litre engine” due to the added complexity and weight, plus the lack of efficiency compared to a four-pot.

While the loss of sound is a massive shame, the performance goals have been more than met. The base 2.0-litre 718 Boxster puts out 296bhp and 280lb ft of torque, a 35bhp and 66lb ft increase over the old 2.7-litre six, while the 2.5-litre in the S also gets a 35bhp increase over the old 3.4 to bring the total to 345bhp, with the 310lb ft torque figure representing a boost of 37lb ft.

Going straight from one of the old cars to one of the new isn’t something we’ve done, but Hofstetter has: “when you drive for a few weeks in a 2.0-litre [718] Boxster and you go back to the 2.7, when you go on throttle you get the feeling the engine is broken,” he says…