Porsche GT3, More Power From 3.6 Liter Engine

With 415 bhp, the new Porsche 911 GT3, is a terrific performer - the fastest 3.6 liter car around, says Porsche. Like previous GT3s, the new model is meant to be equally as home on the track and on the road, and has been honed to become a top performer. In fact, there are GT3 racing classes in several countries. The new car is based on the based on the 997 version of the 911, and promises to be a very exciting car.

Despite its track day ability, the Porsche 911 GT3 makes a very impressive road car, the extra power taking the car to 60 mph in about 4.2 seconds, and to 100 mph in 8.7 seconds, which is 0.7 seconds faster than the old model and that is a lot. Top speed is up slightly at 194 mph.

Distinctive body, but very much a Porsche 911

As usual, Porsche GT3 has some distinctive mods to the body to make it look the part while improving cooling and aerodynamics. At the front the hood is shortened to leave an extra slot so that air leaving the radiators exhausts over the hood. There are five air intakes beneath the bumper.

The sides are unchanged, but at the rear a large wing as well as a built-in spoiler increase down force, while a pair or vents low down at the rear get hot air away. Altogether a great looking car, like the current 911 Carrera with a more than a hint of the power available.

But what really sets the new GT3 apart is the superb new engine: 3.6 liter not the 3.8 liter from the 911 Carrera S. The 3.6 liter continues as the basis for Porsche GT3 because this is a capacity limit for both FIA GT and American Le Mans Series racing.

Porsche GT3 New engine, based on 3.6 liter sports-racer

This new boxer engine, developed from the old GT3 rather than the 911 Carrera develops 415 bhp at 7,600 rpm, and is redlined at 8,400 rpm. Maximum torque is 284 lb ft (385 Nm) at 5,500 rpm. That power output is 115 bhp per liter, which compares favourably with most high-performance engines, exceeding the 112 bhp per liter of the Ferrari V-8 in the F430.

This is a terrific, free-revving engine, with plenty of power from about 4,500 to 8,000 rpm. This extra power comes from changes to the cylinder heads, intake and exhaust system, including a larger air intake and throttle valve. 

Stiff structure, lighter moving parts

To get the engine to rev faster to liberate extra power reliably, Porsche engineers needed to fall back on their racing experience. The engine construction differs from that of the 911 Carrera in that the cylinder heads and cylinders for each bank are in one unit, forming a rigid sandwich construction.

A lot of effort went into reducing the weight of critical moving parts such as the crankshaft, connecting rods and pistons. The counterweights of the eight-bearing crankshaft have been lightened, which reduces 1.3 lb (600 grams) of weight.

Then, the titanium connecting rods are narrower and slightly longer, and each is 5 oz (150 grams) lighter than a steel one. Also changed are the forged aluminum pistons, which are carried on piston pins of smaller diameter. These changes have a critical effect on the ability of the engine to rev faster and produce so much power.

Porsche GT3 Three-stage air intake system

To maintain good power at low and medium speeds, Porsche has adopted a three-stage variable length intake manifold system one length for speeds up to 5,400 rpm, another for 5,400-6350 rpm, and the third for higher speeds. Most makers of high-performance engines have two-stage intake manifolds.

A new exhaust system, with pre-mufflers and the main muffler has been designed to reduce resistance. What’s more, when accelerating hard, the pre-mufflers are bypassed to improve the noise the driver hears all legal, of course. 

Typical attention to detail

Balancing these improvements, the ratios of the six-speed manual gearbox have been altered. All the ratios except first having been lowered slightly so that the full rev range is available at lower speeds.

To get the power on to the road, Porsche GT3 comes with 19-inch wheels and a traction control system as well as a limited slip differential. Ultra low profile tires are used 235/35s at the front and 305/30s at the rear.

This traction control system is developed from the Carrera GT high-performance supercar and features traction-slip and drag-torque control functions, offering the driver a new combination of control and safety. It can be switched off if required.

Further, Porsche GT3 gets a modified version of the PASM system used on the 911 Carrera. This system provides active damping, and when set to sport mode, the damping is quite a bit stiffer than normal ideal for track days.

As standard, the springs and dampers are firmer than on the 911 Carrera, and give the owner some adjustment in the ride height, which is already lower than the other models. The front camber can be adjusted for track driving.

At the rear, control is improved with the replacement of the rubber bushes on the trailing arms with metal joints, and as at the front the tubular anti-roll bar is adjustable.

Ceramic brakes still an option

As standard, the Porsche GT3 gets with 13.78 in (350 mm) diameter cast iron discs front and rear. However, 6-pot front brake calipers are used at the front, and 4-pot calipers at the rear. Porsche’s ceramic discs are an option, now improved with improved internal cooling ducts. The front ceramic discs are 15 in (380 mm) diameter. Apart from much improved braking at high speeds, the ceramic discs reduce un-sprung weight by 44 lb (20 kg) a set.

Overall, the 997 version of the Porsche 911 GT3 takes the model to new heights, with a fabulous engine built with love and care. Thanks to the other attention to detail, drag is low, but down force high, while the weight has been kept down to 3,076 lb, (1,395 kg) - less than 100 lb (45 kg) more than the previous GT3.