HISTORY AND TECH
The 997.2 made history by being the first Turbo since the 930 in 1974 not to use a Mezger-derived engine. The water-cooled 3.6-litre flat six that Herbert Ampferer had conceived for the 996 GT3 and developed for the 996 Turbo had served its purpose. Emissions reasons alone would have justified the end of production, but not only did a brand-new power unit offer better mpg possibilities, the fresh start enabled Weissach to improve refinement and especially torque at low RPM.
The new MA1 3.8 flat six introduced with the 997 Gen2 was also conceived to be turbocharged. This led the way for the separately manufactured Mezger, which had no common parts with the M97 unit, to be replaced by an engine that suited both n/a and turbo applications. Some 15 per cent of the 136,000 first-generation 997s built had been Turbos and there was speculation that the Gen2 Turbo cost Porsche as much as €6,000 less to build, thanks to powertrain savings alone.
The Turbo version of the MA1 3.8 required relatively few non-standard components, with the key difference being a specific crankcase. Assembly on the same line as the naturally aspirated versions simplified manufacture. Furthermore, commonality meant that Porsche’s growing list of drive technologies such as direct fuel injection, Variocam plus and PDK could be integrated on a single engine.
Combustion efficiency was at the top of the Weissach engineers’ list for the blown 3.8-litre engine, and induction ports were shaped to maximise rate of charge and a better fuel/air mixture. Still on the inlet side, valve lift increased by 0.5mm while the valves were 2.5mm greater in diameter. The valve train was lighter than the Mezger’s and the rev limit set at 7,000 instead of 6,800rpm. Similarly, the new design enabled the compression ratio to be raised from 9.0 to 9.8:1.
Beside changes to the intercoolers, the exhaust was substantially rethought. The previous one-each-side catalytic converters were now twinned, their monoliths constructed to reduce resistance yet work more effectively than before. Exhaust diameter increased from 60 to 65mm and the silencer received a less-restrictive baffle.
The Gen2 Turbo’s maximum power of 500bhp and torque 479lb/ft between 1,900 and 4,000rpm were, as intended, improved upon by the S. Here, Porsche claimed 530bhp and 700Nm between 2,100 and 4,250rpm. These increases were achieved largely by adjusting boost pressures and without changes to turbos or intercoolers.
The 997 Turbo S was the first Porsche to be available with PDK only.