The Porsche 911 GT3 is as a high performance version of the Porsche 911 sports car. It is the latest in a long line of high performance models which began with the 1973 911 RS. The GT3, named after the FIA GT class it was intended for, has a 3.8 litre naturally-aspirated six cylinder engine which is based on the unit used in the Porsche 962 and Porsche 911 GT1 race cars.
Since its launch in 1999 a number of variations, designed for both road and track, have been added to the range. The current range (997) includes two road and three racing models. In addition to this, Porsche are currently developing a hybrid version which uses two electric motors and a Kinetic Energy Recovery Systems which was initially developed for Formula One.
The GT3 has had a successful racing career both in the one make national Porsche Carrera Cup series, the international Porsche Supercup and also winning numerous championship and endurance races including the GT class of the American Le Mans Series seven times, the 24 Hours of Daytona outright and the 24 Hours Nürburgring five times.
The engine of the GT3 sets it apart from most of the other 996 models although it shares the same basic 3.6 liter displacement of the standard 996 type so-called “integrated dry-sump” flat-six engine. Along with those of the GT2 and Turbo, it is actually based on the original air-cooled 911’s versatile, true dry-sump crankcase, with an external oil tank. The original version of the GT3 had 360 PS (265 kW; 355 hp), compared to the 300 PS (221 kW; 296 hp) of the regular 996.
In GT3 configuration, this so called “split” crankcase (meaning the parting line of crankcase is on the crankshaft centerline) uses, instead of a fan and finned cylinders, separate water jackets added onto each side of the crankcase to cool banks of three cylinders with water pumped though a radiator. Thus, the GT3 engine is very similar to the completely water cooled 962 racing car’s engine, which is also based on this same crankcase. The 962 differs, however, by using 6 individual cylinder heads while the GT1/GT3, like the air and water cooled Porsche 959, uses 2 cylinder heads, each covering a bank of 3 cylinders. The GT3 engine could thus also be thought of as similar to a 959 engine, but with water-cooled cylinders.