Aside from the GT3/RS, there have basically been two naturally aspirated (non-turbocharged), water cooled, flat 6 cylinder engine designs manufactured by Porsche since the introduction of the 1997 Boxster.
These two engine designs are classified with the M96 and the M97 nomenclature. The M97 is superior and has various upgrades over the M96. These upgrades mainly lie in the IMS (intermediate shaft) bearing area, but the M97 was not introduced until the 2006 MY (Model Year). The M96 IMS bearing has been to blame for many of the commonly known engine failures, hence the desirable larger IMS bearing in the M97 engines.
The new 997-2 (2009 on) engine (MA1) appeared and is quickly proving to be mechanically superior to both the M96s and M97s. It is classified as the MA1.01 for the 3.8 liter, and MA1.02 for the 3.6 liter. Eliminating the Intermediate Shaft and even one more timing chain, the engine utilizes just two camshaft timing chains, which simplifies the water cooled modern flat-6 engine design even further.
The only commonly feared issue with the new MA1 engine is based in the direct Fuel Injection (DFI) system. All automobile manufacturers are having issues with gasoline engine DFI implementation. This is due to the fact that with a DFI system, the fuel injector nozzle sprays directly into the combustion chamber (cylinder and piston area) causing excessive carbon to build up on the intake valves which adversely affects engine performance and operation.
Earlier fuel injection system design had fuel spraying before and on the intake valves. This helped to keep the intake valves cool and clean. We are interested to see how Porsche rectifies this situation.
Tony Callas & Tom Prine