For those wondering about the 992 GT3 engine, this article is an interesting read, given the source...

"Porsche investigating 9500rpm street-legal 911"

The man behind the spellbinding new 4.0-litre, 9000rpm flat-six in the 991.2 911 GT3 has hinted that the ultimate naturally aspirated Porsche road car could still be yet to come.

With rumours of the next generation GT3 going turbocharged, some Porsche enthusiasts could be forgiven for worrying that the 383kW/470Nm unit in the latest 991.2 GT3 RS is as potent as atmo Porsche engines will ever get.

But speaking to MOTOR at the launch of the new GT3 RS, Thomas Mader, Project Manager GT Road Car Engines, said the latest iteration of the 4.0-litre atmo engine will not be the last. "I don't think so," he told MOTOR. "We're working on that with our team, we're looking at power, driveability, we're looking towards the future ... Developing is going on, so we will see."

Mader, who used to work in Audi's motorsport engine department, said it was possible to stroke the engine for further capacity, letting imaginations run wild of a 991-series equivalent of the fabled 997 RS 4.0, whose Mezger engine was then the largest capacity ever fitted to a road-going 911. Mader didn't say if Porsche had seriously investigated an increased capacity version of the GT3's engine, saying only "our engine designers would have to look at that".

Instead, he said more revs were a possibility for the road. The 4.0-litre GT3 engine is almost identical to that of the RSR, GT3 Cup and R racers, save for different airboxes, air filters and exhaust systems. The race engines also do away with the variable intake system of the road cars. The version of the 4.0-litre in the 991.2 RSR revs to 9500rpm.

"This is also a point for development," revealed Mader. "We will look at the things we have on racetrack to put it in the street car, that's our job. The point is, this makes sense, because you want to have power, driveability."

Mader stressed that any such execution would require a rethink of the rest of the car. "For [the new GT3 RS], [9000rpm] is matched perfect to the whole system. Now I have to speak to my colleagues and we will have a car, and we will have 9500 revs, and matched to that all to the gearbox, then we will work on that technical side, which should be possible ... but [although] we have that engine for the racetrack, the lifetime aspect for road car is different."

Mader was mum when asked about reports of the next generation '992' GT3 going turbocharged, instead saying that "there will be a future" for natural aspiration and that more gains are available in making naturally aspirated engines more fuel efficient.

"I would work on precise internal combustion," he said, in describing how to make an atmo engine more fuel efficient. "It must be very precise with timing, the amount of fuel you put in the engine, then you have very low emissions engine. Then you have the exhaust cleaning systems."

The 4.0-litre naturally aspirated unit in the new GT3 could go down as one of the greatest engines of all time, combining a 13.3:1 compression ratio and screaming 9000rpm redline for 383kW and 470Nm in the new RS, its 15kW/10Nm hike over the 'base' GT3 owing only to the ram air effect of the Turbo widebody inlets and more aggressive variable cam timing.

Mader also said it was "technically possible" to mate the Getrag six-speed manual transmission in the 991.2 GT3 to the higher output engine of the GT3 RS.

Watch this space.

Link: https://www.whichcar.com.au/news/porsche-investigating-9500rpm-street-legal-911