With a new 911 on its way and the Carrera lineup featuring exclusively turbocharged motors, there's a suspicion that the next Porsche 911 GT3 and GT3 RS might move to turbo powerplants. We don't think this will happen, for a very specific reason.
It has to do with Balance of Performance (BoP) The most dreaded acronym in sports car racing plays a big role in the continued existence of Porsche's naturally aspirated flat-six. At the premiere of the mid-engine 911 RSR race car back in 2016, Dr. Frank-Steffen Walliser, head of Porsche Motorsport, explained why.
"We opted for a normally aspirated engine mainly for weight reasons," Walliser told R&T at the time. "Because power and torque are balanced by BoP anyway, we said 'what is best for the car?' And less weight is always better [...] that's why we opted for natural aspiration."
Without turbos, Porsche's racing engine is lighter. In the BoP era, where power-to-weight is theoretically equalized among all competitors, a lightweight engine means the ability to add more weight to the car in the form of aerodynamic devices; it also allows engineers to fine-tune the car's weight distribution as they add ballast to get up to the minimum weight prescribed in the rules.
For that reason, Porsche using a turbocharged engine in the RSR would neutralize that advantage. And that's where the 4.0-liter naturally-aspirated flat-six used in the GT3 and GT3 RS comes in.
that all cars in the LMGTE class—in which the RSR competes—must be powered by an engine derived from a series production unit installed in at least 300 street-legal cars. IMSA has similar rules for its GTLM class, where Porsche fields two RSRs. In other words, if Porsche wants to use a naturally aspirated engine in its race car, it has to offer one in a street car. That engine is, of course, the 4.0-liter naturally-aspirated flat-six in the 911 GT3 and GT3 RS.
So, why does this make us think the next GT3 will stick with a naturally aspirated engine? Well, unless the FIA and IMSA get rid of BoP—which is very unlikely—there's a benefit to Porsche leaving the turbos off its racing 911. That means, until the next major rules change, Porsche has a practical reason to build a naturally aspirated flat-six road car.
Of course, Porsche could pull out of GT racing entirely, but that's even less likely. Porsche may have abandoned LMP1 over escalating costs, but not racing the 911 would be unthinkable for the brand.
And Porsche Motorsport isn't dumb either. The people there know that the naturally aspirated flat-six plays a huge role in why people by GT3s and GT3 RSes, especially now that the rest of the 911 lineup has gone turbocharged. It's a win-win situation—the ideal race-car engine makes for a more compelling street car.
Speaking at the 2017 Frankfurt Motor Show, Dr. Walliser told R&T that while the 911 GT2 RS has moved to turbo power, Porsche is still committed to a naturally-aspirated GT3. He even pointed out that the GT3 would likely go hybrid before it went turbo, though there are no current plans to build such a vehicle.
So, if someone tries to tell you that the next GT3 will go turbocharged, don't listen to them. In a world where racing and street cars seem further apart than ever before, it's fascinating to see how BoP is dictating decisions on at least one of Porsche's production cars.