This stretch of road I know. It runs from the A8 Autobahn to Muhlhausen and into the hills. A short downhill straight leads into a dip and then an open, uphill S-bend with good visibility. Normally, I’m hesitant to keep the throttle pinned here because the dip tends to unsettle most cars — right where you’ve got to turn in and commit.
After a couple hours of hard driving in Porsche’s 2010 GT3, however, I’m feeling a bit braver than usual. Its awesome capabilities are more accessible than in versions past, and that leads to the confidence to push harder. A quick heel-toe downshift to third comes before settling the car and getting ready for the dip. Old GT3s — especially 996s — would bounce their noses in a pronounced manner at the dip, unsettling the front end just when you needed all the grip you could get up there. The new GT3 processes the bump better, yielding the grip I need to commit to the turn on throttle.
Revised suspension settings mean the new GT3 is tangibly more neutral. It feels every bit as sharp as the last 3, but has less of a tail-led feeling at eight-tenths, two steps before exceeding the limits of the wide, grippy Michelin Cup tires out back. At least, that’s my read within sane limits on a deserted public road.
The new, 3.8-liter engine hasn’t lost the previous 3.6’s high-revving charm. If anything, the top end is more aggressive — now pulling 100 rpm higher, to 8500 rpm. Just as you think it might be fading past 7600 rpm, it keeps on going. The last 900 rpm may not be of much practical use on the road, but they’re very useful when you want to preserve momentum and ensure you’ll drop right back into the powerband from gear to gear. Low-end torque was already quite good in the first 997 GT3, but it’s even stronger here, the 3.8’s extra torque making the dash between curves an immediate, effortless affair.
If there’s one thing I’m wishing for, it’s the single-mass flywheel of the last GT3 RS. The 2010 GT3’s dual-mass flywheel is a shade lighter in line with an aggressive weight-savings program, but it is still a big, heavy dual-mass unit that doesn’t allow the 3.8 to rev quickly when blipping the throttle for heel-toe downshifts. Good thing the short shifter is as good as ever. The one in this 1,000-mile test car is a bit stiff, but it’s so, so mechanically positive.
Back on the Autobahn, traffic means it will be impossible to verify the car’s 194-mph top speed, but two runs to 174 mph prove the new GT3 is nearly hands-off stable at 150 mph and beyond. Also helping our appetite for high speed is the latest electronically variable suspension system. While the ride seems little different around town, the stiffer springs and revised damping translate into a noticeably better and more secure ride on the Autobahn.
It’s not a bad place to be at speed, this GT3. The interior is as good as any 997’s, which is to say very good indeed. The dash is laid out logically, and the revised PCM radio/nav/phone touch-screen first seen in 2009 Carreras is a welcome addition. Past that, the only changes for 2010 boil down to minor surface treatments, a new three-spoke steering wheel, and Alcantara on the lower dashboard.
When we reach Zuffenhausen, we’re greeted by a wide smile on the face of Andreas Preuninger, the head of Porsche’s high-performance road car division. He has just returned from a test at the Nürburgring with Walter Röhrl, where Ferrari’s F430 Scuderia was used as the benchmark. He won’t be drawn on lap times, merely saying that the GT3 was faster. (We later learn Röhrl managed a seven-minute, 40-second lap.) And, says Preuninger, a new GT3 RS is coming…
The real benchmark for the new GT3, however, wasn’t a car made in Modena. Explains Preuninger: “The previous 996 and 997 GT3 models were a huge success. We sold 5,200 cars — more than double the original sales projection, giving us a very strong business case. When we were tasked to make the car even better, we had a lot of sleepless nights as the GT3 had become so good and so well balanced, making it even better was not going to be easy.”
The development path lead the team down several new roads — one of them being new, “smart” engine mounts. In the past, there have been three approaches to motor mounts: soft rubber for mainstream models, firmer rubber for sporting models, and solid (or near solid) for race cars. All of these are compromises along a continuum. Soft rubber isolates engine vibration and road shock-induced movements the best, but it also lets an engine move around as the car takes a corner. In a rear-engined 911, especially, the fact that the engine can move separately creates a separate polar moment of inertia — a destabilizing factor as the engine may still be moving left as you quickly turn to the right. In racing 911s, where the isolation of noise and vibration for driver comfort is not an issue, the engine can be bolted in solidly so that the chassis and powertrain move as one.
Weissach’s solution is Porsche Active Drivetrain Mounts — an option that will be available in late 2009. In recent years, we have seen magneto-rheological damping in the Corvette, Audi TT, and Ferrari 599. PADM uses a similar concept to change the rigidity of the engine mounts. In normal driving, the fluid-filled mounts absorb vibrations and shocks that shift the GT3’s flat six on its mounts. When PADM recognizes more sporting inputs, however, an electrical pulse charges magnetic particles in the fluid, changing its viscosity and, in turn, the rigidity of the mounts. PADM even works as you accelerate from rest, improving traction and reducing the “torque twist” that stresses a drivetrain and obstructs clean gearshifts.
Part of improving any car is listening to your clients, and Porsche took note of buyers who viewed the GT3’s low, plastic front spoiler lip as “sacrificial.” This was especially true in the U.S., where steep driveways and aggressive ramp angles drove GT3 front lip sales to new heights. The team’s solution was a new, optional pneumatic front-end lift system.
Hydraulic lift systems are heavy and slow, some taking up to 20 seconds to raise and lower the front of a car. The Porsche system raises the front end by 1.2 inches in just a second or so and brings the nose back down automatically at 30 mph. The system weighs 11 pounds, sits very low in the car, and locates its pneumatic supply tank near the gearshift mechanism, in the tunnel used by the driveshaft in the all-wheel-drive Turbo and C4S. The pump is the same one used to power the PASM damping system.
If it sounds like Porsche’s purest 911 is getting more and more complex, it is. But Preuninger is quick to point out that his team worked hard to offset any weight gains that came with new technology: “We literally examined every piece of metal and plastic on the car to see where we could remove weight without losing strength.” Thanks to his team’s efforts to trim weight wherever possible, the 2010 GT3 is said to weigh the same 3,075 pounds as the 2008 model, despite all the extra equipment and technical improvements.
The new center-lock alloy wheels are just one example of this philosophy. While Preuninger does not deny the marketing advantages of going to center-locks, he says the 19×8.5- and 19×12-inch alloy wheels are lighter: “There is a 6.6-pound savings across the set of four, 1.1 pounds per rear and 2.2 pounds per front.”
Why do the narrower front wheels save more weight? Specificity — where the last GT3 wheels could be bolted onto a heavier 997 Turbo, the new center-lock wheels are unique to the GT3 and can thus be tailored exactly. With less maximum load capacity, they can be lighter. The system, an evolution of the center-lock hubs used on Carrera GTs and 997 GT3 RSRs, presents two real downsides for trade-up track-day enthusiasts: Their extra five-lug wheels won’t fit and aftermarket wheel choices will be limited, at least initially.
The new GT3 rolls on Michelin’s latest Pilot Sport Cup tires, in 235/35ZR19 and 305/30ZR19 sizing. These utilize a new compound, primarily due to new European laws preventing certain chemicals from being used in tire rubber. Says Preuninger: “Performance is pretty much the same as before in the dry, but wet grip is a bit better. With 4.5 millimeters of tread depth when new, wet performance is as good as any normal tire with the same tread depth. Of course, aquaplaning on standing water is the main issue. The driver has to realize that this tire is really focused on dry performance.”
The optional PCCB brake system is the same as the one used in 2008 GT3s, but the standard brakes have taken a significant step. “The old steel brakes used 350-millimeter front discs,” explains Preuninger. “We now use 380-millimeter discs with aluminum hubs located with stainless steel bolts. The weight saving is 600 grams per rotor compared to the old system, even though the discs are larger!”
The new, two-piece rear discs measure 350 mm and also shave 600 grams. While brake cooling is unchanged up front, Porsche fit new components to channel more cooling air to the rear discs. The company says these lowered rear brake temperatures by up to 140º F during intense track testing, with noticeable benefits in pad performance and wear.
The more capable standard brakes reflect changes made in the engine compartment. Weissach had decided that it was time for more cubic inches. Explains Preuninger: “We had reached the end of the road with the 3.6 in two respects. If we further increased power, we would lose tractability and emissions and impact long-term reliability. Secondly, the FIA GT rules had changed in the intervening years. Where we were previously only allowed a 3.6-liter maximum, we can now run up to 4.0 liters as we now do with the RSR. This gives us a lot more freedom to play around with the capacity of the road-legal homologation car. It is in our best interest to take full advantage of that.”
The racing department was consulted, and it viewed 3.8 liters as the optimum displacement for the road car. Says Preuninger: “The 4.0-liter RSR engine uses a different crankshaft, and we decided early on that we did not want to go down that road for a number of reasons. We wanted to retain the proven crankshaft from the 3.6-liter version of the venerable dry-sump GT1 motor because its short stroke gives the engine its free and high-revving nature, something GT3 drivers tell us is vital to the car’s character.”
Changing the 100-mm diameter pistons for 102.7-mm pistons reduces the amount of metal between the cylinders. To compensate for the loss of rigidity in the cylinder blocks, steel liners from the GT3 RSR replace the alloy liners used in the last GT3. The steel liners may carry the same part number as the ones used in the racing RSR, but they add weight — 6.6 pounds of it — to the back of the car.
“We went through a serious weight-paring process in other areas of the engine to compensate for this,” says Preuninger. “We looked at everything from tappets to the dual-mass flywheel, shaving off a gram here and a few more grams there, even using expensive parts like magnesium brackets.” The result is a 3.8-liter engine that’s 3.97 pounds lighter than the 3.6 six it replaces.
The 102.7-mm forged pistons are married to the same titanium connecting rods as before, but the forged steel crankshaft has been shot-peened for extra hardness. The combustion chambers in the cylinder heads are mechanically polished to ensure the compression ratio of 12.0:1 is precise across all six cylinders.
Previous GT3s used VarioCam Plus variable intake camshaft timing, and the new car benefits from refinements to this system as well as the intake plenum to take full advantage of the added displacement. The real news, however, is that the GT3 3.8 is the first Porsche to use variable exhaust cam timing, as well. “The new cams added 3.3 pounds to engine weight, but the low-rpm torque is significantly improved and exhaust emissions are lower, as well,” says Preuninger.
As the existing exhaust-pipe diameter did not restrict the 3.8, the exhaust system was carried over. “It is a relatively light system with a good acoustic, so we saw no reason to change it,” explains Preuninger. The final numbers seem to confirm that restriction isn’t a problem in the 3.8, which is rated for 435 bhp at 7600 rpm and 317 lb-ft of torque at 6250 rpm. The specific output of 114.6 horsepower per liter is an outstanding number for a normally-aspirated engine.
Some will wonder why Porsche didn’t adopt direct fuel injection. Preuninger is ready with an answer: “We already run a very high compression ratio on this motorsport-derived engine compared to a mainstream Porsche motor. So adding DFI would have meant a lot of extra work and weight for very little gain. As it stands, we improved fuel economy and emissions over the old 3.6 motor.”
The other bit of new Porsche technology not considered for the GT3 was the PDK double-clutch gearbox. “Apart from the fact that GT3 drivers want a manual and the GT3’s short shifter selects ratios faster than a normal manual, PDK adds 66 pounds to the wrong end of the car,” offers Preuninger. “Mechanically, it does not fit the GT1 block anyway; a special flange would have to be made. Beyond that, the PDK box is longer and would create a packaging issue.”
The six-speed manual is broadly similar to the previous one. “The differences came out of our weight-savings program, where we found ways to shave a few grams here and there without compromising strength or durability,” continues Preuninger. “The one significant mechanical change is a shift in the way the gears are locked onto their shafts. A few hard-core clients asked for more easily interchangeable ratios, so we adopted the motorsport system.” The limited-slip diff is carried over unchanged and locks up 40 percent on acceleration and 28 percent on decel. Gear ratios are unchanged, so top speed only moves up one mph.
“We did not set out to make the new car faster in top speed,” says Preuninger. “Even in Germany, there is too much traffic to extend any car past 300 km/h (188 mph) for more than a few seconds unless you get up very early on a Sunday.”
Attaining such speeds is one thing, doing it in a relaxed manner is another. The 996 GT3’s nose got light beyond 155 mph and it was nervous in crosswinds at high speed. The first-generation 997 GT3 was far better and very stable at 190 mph, but the latest GT3 takes aerodynamic stability to a new level with literally five times more downforce. “The trick was to achieve this without seriously affecting drag,” explains Preuninger. “We spent weeks in the wind tunnel, and achieved the significant downforce we were looking for with the Cd climbing slightly from 0.30 to a still-good 0.32.”
The GT3 boasts 88 pounds of downforce up front and 154 pounds in the rear at 188 mph. “Where most cars have 220 pounds of lift at that speed, we have 242 pounds of downforce,” says Preuninger. “This equates to over 440 pounds more downforce than a normal car. The added stability is significant — you can do a lane change at 155 mph without feeling like you’re going to fly off the road!”
The adjustable rear wing uses 7.0º of attack as the default setting, but can be adjusted to a maximum of 11º to increase downforce for tracks like the Nürburgring. “You can reduce the angle of attack to 3.0º for top speed,” notes Preuninger. “In the wind tunnel, this looks like it might benefit top speed by up to 3 mph, but in real-world testing we found the gain is only .9 mph. This is due to the fact that the slightly lower downforce changes the car’s attitude just enough to increase drag.”
The new front spoiler creates as much downforce as the one on current GT3 Cup racers. Says Preuninger: “The center section creates more downforce than before. You will find that the one on the next GT3 Cup does not look much different.”
Some suspension components had to be strengthened to deal with additional stresses created by more downforce. The hubs and their carriers were among them, and it was an ideal time to revise them as they were up for tweaks to improve the GT3’s handling dynamics. Says Preuninger. “We lowered the roll center up front by nearly two inches and changed the rear axle’s roll center so we have a straight line between the two points parallel to the ground. This gives less understeer and a more stable rear end.”
The fully-adjustable coil-over suspension is largely the same. Ride height and strut-top settings are both easily altered, while shims can be used to increase negative camber to the point that slicks can be used. The front springs are now rated at 45 Nm/mm while the rears are 105 Nm/mm — an increase of 5 Nm/mm all around. The anti-roll bars have been softened to compensate and recover ride quality. The front bar’s diameter has been reduced from 28 mm to 25 mm, while the rear bar diameter is now 23 mm instead of 25.2 mm — the same as the 997 GT2. To minimize weight, the bars are hollow.
Preuninger seems particularly proud of the latest electronic stability management system in the GT3 3.8: “We think our latest PSM system is the best of its kind, especially in wet conditions. Developed in conjunction with Bosch, the latest version allows you to deactivate Stability Control and Traction Control separately. It’s very unobtrusive and makes it hard to throw the car off line on a wet track.
“As before, so long as you are smooth, you can even drift the car at a reasonable angle with the system on,” he continues. “But you can now switch it off completely and it will not come back even if you hit the brakes — so you are on your own!”
With no track to sample the GT3 on, we weren’t about to throw the new car sideways at speed. Our time with the car on German back roads and autobahns did, however, give us a good measure of the car. So, how good is it? That’s a question that must be answered in terms of how much better it is than the last GT3.
Truth be told, the new car, for all its advances, is not a huge leap forward. Areas where the last GT3 was already good have been improved by tangible degrees to match the slight improvement in power and torque. The biggest benefit is an aerodynamic one. Together with the chassis upgrades, this yields a big difference at speed — but it’s something few Americans will be able to enjoy.
In everyday road use, the overall feeling isn’t much different, apart from a better torque curve. On a fast country road or an open stretch of autobahn, though, everything comes into focus. This is Porsche progress, subtle but sure. The continued development of the GT3 has created a civilized track-day toy that, unlike its competitors, really can be driven every day. And the fact that it is now quicker at the Nürburgring than Ferrari’s best bodes well for the GT3 RS to come…