just curious what makes this engine so great ?
thanks

The biggest differences I read in one of the 911 design books I bought were in the oiling passages and the dry sump.

Mike

This is about the GT3, but much will apply for the turbo as well:

Track bred, street ready
The Porsche 911 GT3 is the most direct link between a road-going sports car and a track-proven racing car. Conceived, designed and built for undiluted driving dynamics, the drivetrain, suspension and aerodynamics of the car provide a unique synthesis of everyday driving qualities and thoroughbred racing technology. The heart of the new Porsche 911 GT3 is of course the six-cylinder boxer engine. Originally built for the Porsche 911 GT1, this exceptional engine has proven its qualities time and again throughout several stages in the evolution process, boasting the same technology and engine features in the Porsche GT3 Cup, the GT3 RS, and the GT3 RSR. Developing a specific output of 115.3 bhp per liter, this power unit ranks at the top of all normally-aspirated engines in cars currently homologated for road use. This performance is the result of a consistent, far-reaching process of ongoing development seeking to increase engine output without increasing the size of the engine itself. Displacing exactly 3.6 liters, the six-cylinder featured in the new 911 GT3 capitalizes on the displacement limit allowed in its category of motorsport, developing 415 bhp at 7600 rpm and reaching a maximum engine speed of 8400 revs. Peak torque, in turn, is 300 lb-ft at 5500 rpm. By comparison, the former 911 GT3 developed maximum output of 381 bhp at 7400 rpm and peak torque of 284 lb-ft at 5000 rpm. Over and above the efficient power and torque of this extremely compact engine, the new 911 GT3 excels in its quick-revving qualities and immediate response throughout the entire rev range.

Lightweight technology promotes a high-revving powerplant
The objective in developing the engine was to enhance the high-revving concept. To reach even higher engine speeds, Porsche's engineers have reduced mass and the mechanical loads acting on the engine's moving parts. On the new GT3, this applies most directly to the pistons, connecting rods, and crankshaft. The result of these improvements is an increase in maximum engine speed from 8200 rpm on the former GT3 to 8400 rpm on the 2007 911 GT3. The improvements made on the forged pistons involve not only the new shape of the pistons, but also the size of the piston pins, which have been reduced in diameter by 1 millimeter to 21mm. This adds up to an overall reduction of weight on each piston (including the pin) of approximately 30 grams. A further improvement is the re-design of the piston crown for enhanced combustion. To increase maximum engine speed, the titanium connecting rods have been extended in length by 1.5 millimeters to 131.5mm. This allows a smoother transition of reciprocating force from the connecting rods to the crankshaft, while reducing loads acting on the various components. Since the upper conrod opening now houses a thinner piston pin than before, the entire connecting rod is also thinner. Weighing just 418 grams, the titanium connecting rods are approximately 150 grams lighter than comparable steel rods. In the process of revising the crankshaft, which runs in eight main bearings, Porsche's engineers concentrated on optimizing the shape and design of the crankshaft webs to lighten the structure by 600 grams. This allows higher engine speeds, but also improves the engine's response. The crankshaft bearings are now also hardened in a nitro-carbonating
process.

Dry sump lubrication for the toughest racing requirements
As before, Porsche's classic dry sump lubrication system with a separate tank ensures a reliable supply of oil to the engine even under the extreme conditions encountered on a race track. The oil pump is driven by the crankshaft via a layshaft and a connecting shaft. The pump itself is made up of three segments, one of which is responsible for supplying compressed oil to the engine. This supply unit extracts engine oil from a separate oil tank, sending the oil through an oil/water heat exchanger and oil filter before continuing into the engine oil circuit. The other two pump segments draw out the oil accumulating in the crankcase and pump it back to the oil tank. The increase in power and performance obviously means higher temperatures and thermal loads within the new GT3 power unit. To offset these higher temperatures, Porsche's development engineers have opted for a larger water pump and a radiator with larger surfaces.

Engine block in sandwich structure
The engine block is fundamentally the same as that of the former GT3 power unit, meaning that it is built in a sandwich structure. The cylinder cases, cylinder head and camshaft cases of each row of three cylinders on the right and left side are combined to form one unit, to increase the torsional stiffness within the engine. Unlike the engine in the 911 Carrera®, the cylinder cases are not connected with each half of the crankcase. This is because the power unit of the GT3 serves as a homologation engine for motorsport, and this elaborate configuration was chosen in order to respond quickly to any changes in engine-size categories. The cylinders cases are made of a light alloy featuring aluminum, with Nicosil-coated liners. In the interest of more efficient combustion as well as enhanced fuel economy, the compression ratio has been increased from 11.7:1 on the previous-gen GT3 to 12.0:1 on the 2007 model. The cylinder heads are made of a temperature-resistant light alloy, and are nearly identical to the cylinder heads on the former model. The exhaust valve rings are now cooled directly by coolant running through an additional duct, and heat dissipation is enhanced with sodium filled exhaust valves. The valves are precisely engineered for minimum tolerance and interact with cup tappets also optimized for minimum weight and feature hydraulic valve play compensation. To ensure that the valves always close properly even at lofty revs, both the intake and exhaust valves feature double valve springs. The finishing touch is polished intake and exhaust ducts to provide minimum resistance in the gas charge cycle.

No RMS, like all the other engines.

I would of thought it would of been the predecessor to the new 996 turbo being a twin turbo ,watercooled 4 valve engine compared to the previous aircooled two valve engine of the 993 turbo.

I know the block is great, are they going to keep the block???

If not. wet sump + lesser block = fail.

GT1

This has been the standard (super stiff) block generally reserved for the turbocharged 965-993-997 (or GT2/3) series of Porsche. There have been changes to the basic design, but this GT1 series is specifically the 3.6 liter powerplant, though the 965 Turbocharged cars had different cylinders and thus were a 3.3 liter Turbo on the same base GT1 engine block. I *believe* that the 993 3.6 liter motors (in naturally aspirated form) also kept the GT1 block but that the 996-Series was the one in which the N/A cars (with the 3.4 liter motors) did not some with that foundation (block).

So a 996-Carrera with the 3.4 liter and the aero-kit is never going to be a GT3, for example. They just don't have the same motor. Fundamentally different. You can dry-sump ANY motor you want so that doesn't have anything to do with it. The GT1 was a race-inspired design which was much stiffer. It's likely a reason that most of the 1990-1998 Porsche's were so indestructible pretty much no matter which car you purchased. It's also probably a reason I have heard of several 996-N/A cars experiencing cracked blocks under severe usage. Yes it's a Porsche.... but they just don't hold up as well. It's definitely a motor designed for STREET duty.

SY