Gemballa Widebody 996 Twin Turbo Cabrio
That this car is no ordinary 996 is obvious from a distance. The fenders are widened front and rear, and the rocker panels are replaced with wider sills featuring integrated air intakes. Gemballa's modifications are distinguished from most others by being all in steel, making them an integral part of the vehicle. The wheel wells are extended, and all the exterior metal visible on the relevant panels is new. The changes are cleanly integrated with the remaining bodywork and avoid a pretentious racer wannabe look. As far as I could tell, all the steel was perfect, and the paint appeared to be of factory quality.
Many of Gemballa's competitors modify bodywork by adding fiberglass. In theory, I prefer steel for a variety of reasons. Steel won't pop off the steel if it is bumped, especially in cold weather. Steel can be given factory levels of corrosion protection, while resins absorb water if they are not sealed absolutely perfectly. Steel can be repaired without starting over or using excessive filler. Steel should be lighter than fiberglass, which requires a great deal of filler to be integrated perfectly, and, for the same reason, steel fenders ought to be faster and less labor-intensive to install. In real life, only time will tell how much of this reasoning applies to any given car.
In addition to the changes in steel, Gemballa added a new front bumper with three air inlets and a spoiler lip, and a carbon-fiber hood. The hood calls to mind every previous 911 with its wide air intake, but also illustrates why I prefer steel body parts. The resins used to make most composites are not dimensionally stable through the curing process, so it is difficult to make perfect composite parts. On this car, the gaps between the edges of the hood and surrounding panels were wide and inconsistent, and, at the cowl, the corners of the hood did not line up well with the corners of the fenders.
Gemballa gave this car's interior the full leather treatment, and the results could not be more sumptuous. I thought our long-term 996 looked good, one of a few cars that can compete with the TT on interior design, but the factory plastics look almost cheap next to the Gemballa car, in which virtually every interior surface has been covered with a finely finished leather. Nowhere could I find a wayward edge or an imperfect stitch, and the color was tastefully chosen to match the factory leather, rather than some contrasting hue of annoyo-glow. It was truly beautiful.
Additionally, Gemballa replaced the pedal surfaces, steering wheel and seats. The latter are Recaros with electrically adjustable backrest, integrated headrest and a backrest ventilation system. They are prepared for the installation of four-point harnesses and covered on every surface with the same leather as the rest of the car. Any customer who is fortunate enough to not have to ask how much it costs will undoubtedly be very pleased with the leather package.
The performance enhancing modifications on this car are significant. Most obvious is the turbo, a step other tuners have been reluctant to take in light of early problems with the new watercooled engine. Gemballa was well aware of the dangerous and expensive ground it was treading, and spared no cost in preparing the hardware to deal with increased loads. It began by reinforcing the block itself and specially modifying the cylinder heads. Stronger connecting rods were attached to forged pistons that lowered the compression ratio from 11.3:1 to 9:1.
The turbo installation itself is nothing if not elegant. A pair of KKK turbochargers resides at the back of the engine, blowing upward through an air-to-liquid intercooler directly to the factory throttle body location. There is no giant wing to house an air-to-air intercooler, and no long, circuitous plumbing to undo much of the turbos' pressure-building work. The pump that circulates intercooler liquid to a front-mounted radiator is driven from the crankshaft, eliminating the weight of an electric motor. The 9 liters of water in the system provide a significant thermal reservoir that can potentially provide transient performance superior to an air-to-air intercooler system. Of course, the turbo package includes a free-flow exhaust system, as well as an additional oil cooler and a heavy-duty clutch capable of handling 515 lb-ft of torque. If one reads the dyno graph included in Gemballa's literature and converts from kW and Nm correctly, one finds that the twin turbo engine produces 445 bhp at 6950 rpm and 390 lb-ft of torque at 5300 rpm. Those numbers are fairly close to the factory's turbo, so there are no signs of certain impending doom on the horizon, especially if the internal reinforcements perform as intended. Unfortunately, the software is not yet perfect. The engine would not start without a touch of throttle, whether it was cold or hot. Sitting still at idle, waiting for instructions from the photographer, the car was smelly. I don't know exactly what I was smelling, but my guess is the fuel mixture was imperfect. Generally, I expect not to smell the exhaust of a 2000 model-year car.
On a straight road, first-through-third-gear acceleration is what you would expect in a 3,100-lb car with 445 bhp and at least that many pounds of humanity inside it. Which is to say, suburb. We didn't have the opportunity to get real numbers, but Gemballa claims a believable 0 to 100 km time of 3.9 sec. and says the car can reach redline in sixth gear, which would occur in the vicinity of 190 mph.
Suspension upgrades were as thorough as those done to the engine. It is usually difficult to improve meaningfully on a car that's as good as the 996, but Gemballa has done just that, despite one or two stumbles. The front control arms were replaced, and rubber rear suspension bushings were exchanged for solid ones. Stiffer anti-sway bars were installed front and rear. The heart of Gemballa's system is H&R's performance street coilover system with adjustable ride height front and rear. These coilovers are hand-built in-house by H&R in Germany to ISO 9001 standards and are specified from the factory on the 911 GT3. Roland Graef of H&R stated the system is engineered to provide a nice, comfortable street ride while also working well for competition and recreational track use.
The total effect of the suspension changes was to transform the Porsche, giving it sharper and more precise responses, both in turn-in and while in a turn.
The Gemballa was a fine-handling car, certainly among the most enjoyable I have driven, and a very fast one, too, thanks to the twin turbos. In several ways, it is not as perfect as the factory car, but that is a price to be paid when you must have what the factory will not build. This car is faster and handles better than a stock normally aspirated 996. It remains to be seen how its performance will compare to that of the factory Turbo, but to many eyes, Gemballa's coachwork is more beautiful than the factory car's, and anyone will admit that the interior is far more luxurious. Furthermore, there will not be a 996 Turbo Cabriolet. For customers who must have a convertible and a turbo, that will make the difference. Not everybody wants to be Darth Vader.
AutoThority's 993 Turbo
Six hundred and seven horsepower means there's never enough road. In fact, you rarely get the chance to use sixth gear. Roads that were once long sweepers requiring barely a nudge on the steering wheel become corners with turn-in points, apexes to hit and a wheel to unwind. Flying through these sweepers, hard on the gas, the front end starts to wash out due to the weight transfer of the squatting rear end. The steering gets lighter, and the tires turn down the volume on your conversation. But, as much as you want to stay on it, you lift just enough to get the front tires to start biting again.
It's not how fast AutoThority's Stage 3 993 Turbo reaches triple digits that impresses (0 to 60 in 3.21 sec., 0 to 100 in 7.11, quarter mile in 10.16 at 143.04 mph), it's how hard it charges once it's there. Where most cars start to struggle, this straight-seeking missle is just begining to show its strength. The needle flies by 110, 120 and 130 as if it were unleashed from a high-tension spring. Passed cars seem to be sitting still or going in reverse. On short straights, we saw 140 mph with the only things keeping us from more being a lack of road and the fear of jail time.
AutoThority's Stage 3 993 Turbo may be the only car large enough to match Donald Trump's ego. To wring out 607 bhp, AutoThority replaces the stock compressor wheels with larger units so they keep flowing where the stock units start to drop off. The ECU is reprogrammed for boost control, ignition timing and fuel injection metering. A GReddy fuzzy logic boost controller then allows the driver to add as much as 1.2 bar. To flow enough fuel, AutoThority uses a fuel pressure regulator from a 993 GT-2. A high-input mass flow sensor, wastegate actuators that hold boost longer and blow-off valves are also part of the Stage 3 package.
Special cams are integral to this process, while the Stage 1 and 2 kits use stock cams. The numbers on the cams are similar to the GT-2's. The stock intercooler is replaced by a unit twice the thickness and twice as efficient. Exhaust is improved via high-flow cats and a stainless steel exhaust system. The sound is throatier, angrier and battles the flat six's frenetic heartbeat for your ear's attention.
Blip the pedal, and the revs spike and drop quickly due to the lightened flywheel. The clutch, from the GT-2, engages quickly and asks for light feathering of the gas. From idle, the engine pulls with as much vigor as an unmodified twin turbo. Driveability has not been lost. Boost comes on at the same revs as stock--2800 for the first turbo and 4000 for the second--only with a much bigger wallop. The interior is filled with the "whoosh" of spinning turbos, and a lift of the throttle causes the "hiss" of bleeding wastegates. It's chicken soup for the soul of a madman, and it's incredibly addictive. This Stage 3 kit should also come with a 12-step program for those who get drunk on the thrill of warp drive. A false identity wouldn't hurt, either. And for passengers, adult undergarments and mild sedatives are recommended.
To apply the extra power, AutoThority replaced the stock tires with Michelin's new Pilot Sport tire, adding an extra 10mm for the front tires (245/40) and a sizable 50mm in back (335/35ZR-18) on Fikse forged, three-piece wheels (9x18,11x18) anodized an ominous black. The result is heavier steering and a tad slower turn-in response. The tires also ask for a bit more steering to make the same arc as before. Its cornering attitude is much like the stock 993 Turbo, mild understeer, and it responds well to trail-braking in tight corners. The back end can be coaxed to step out with a stab of the throttle at the right time, and, again, like the stock Turbo, oversteer is corrected when the front wheels bail out a sliding rear end.
Lowered to the point where there's no gap in the wheelwells, it rides on an H&R coilover setup originally designed for the GT-2. Working closely with H&R, AutoThority tested a variety of spring rates until it found the desired ride and handling setup. As expected, the ride is firm but not uncomfortable. The shorter travel stroke can get overworked by a series of big dips, but compared to the stock 993 Turbo, the H&R set does a much better job of controlling roll, dive and squat. The legendary Turbo brakes remain intact; Porterfield race pads are the only modification. Their intial bite isn't as immediate as the stock pads, and they require more heat and greater pedal effort to get working.
Driving the AutoThority Stage 3 Turbo is the kind of experience that inspires deliquency. You become what proctologists look at all day. You look for gaps to squirt through and long lines of cars to pass, any excuse to get on it. Luckily, with the amazing brakes and the four-wheel-drive platform, you're allowed a bigger margin of error. You're forgiven for minor mistakes, incidents that are quickly forgotten when you get on the throttle and take off to that world where the brutal becomes the sublime. You never want to get out of the car.
After the apocalypse, after the earth has regenerated and started new life forms, the next forms of "higher" intelligence will unearth this beast and think AutoThority's masterpiece was built in some secret skunkworks called Area 51.
SPE Twin-turbo 911
Force-fed flat-six motors have been a tuner favorite, because the gains are huge and long-lived. At places like Le Mans, Daytona and Sebring, 911s are so ubiquitous because of their reliability that you can jump from 911 hood to 911 hood and never touch the ground. And while the 911 featured on these pages was intended for street use, it could hold its own on a race track...hell, it might even win.
"We started with the best of the best," said Alex Shen of SP Engineering in Temple City, California. "The 911 biturbo is basically a race car; we expanded its capabilities largely through Porsche's GT2 parts bin."
An engineering graduate at Texas A & M, Shen and his team have been building high-end project cars for six years, both domestic and imports. Our new sister publication, Turbo, just featured SP's 650-bhp Toyota Supra Turbo, a street-legal monster capable of covering the 1/4 mile in a tic over 10 sec. This car isn't quite that brutal--1/4 miles in the high 11s, 0-60 in 3.9 sec and a top speed that exceeds 180 mph. However, reducing this car to mere numbers is like counting the brushstrokes on a Van Gogh. This car does everything with such brilliance, it belongs in very rare company.
The view from inside the SPE 911 is largely factory-spec save for an elaborate Breykrause strut brace mounted between the rear towers and SPE's carbon-fiber inserts Although the stock seats look like basic buckets, they are deceptively comfortable, offering superb support--that's a good thing, as launching this beast without proper restraint would be like shaking a ball bearing in a coffee can.
First gear is laughably brief.
The Porsche pings off the rev-limiter so violently you're thrown forward with enough force to eject old fillings.
Second is about the same.
The engine builds boost fast, and the gear is over by the time your hand leaves the knob for the steering wheel. SP chose a GT2 cam profile that retained much of the bottom end, so the term "turbo lag" does not apply here. Additional fuel comes by way of an upgraded fuel regulator, which feeds blueprinted GT2 injectors.
Third lasts a bit longer but not much, just enough to press internal organs against the spine.
GT2 turbochargers feature larger exhaust housings, which gives the Porsche bigger lungs--coupled with SP Engineering's own free-breathing stainless steel exhaust, you'd swear this car will never run out of steam.
Fourth gear is something just shy of automotive nirvana.
Shen chose a Gemballa ECU for the engine management, because it provided a good compromise between spirited track sessions and trips to the grocery store.
Fifth gear and the Porsche exceeds the take-off speed of a 747 (168 mph).
The pronounced bodywear is as purposeful as it looks. The big GT2 wing provides considerable downforce at speed and features an adjustable lip to fine tune its effectiveness. The nose has been fitted with a Motorsport airdam, and the side skirts are Gemballa pieces--all of which are fabricated from carbon-kevlar composites.
"I have an extension for the wing, another GT2 piece that adds even more downforce, but I don't really need it,"said Shen. "Besides, every kid with a Wings West Honda wants to race me...it's kind of embarrassing."
Sixth...well, 200 mph seems entirely possible.
The underpinnings have been massaged with custom-wound H&R lowering springs and Bilstein dampers, and the front/rear swaybars are thicker GT2-spec units. Shen had the crew at BBS build him a special set of wheels--super lightweight shoes wrought from magnesium. The mags measure 9x18 in front and 11.5x18 out back and carry Bridgestone SO-2 rubber sized at 235/40ZR-18 and 285/35ZR-18, respectively.
The folks at Irwindale Speedway were kind enough to let us flog the biturbo around the track's banked oval. While it was great fun, its 1/3-mile circuit seemed to frustrate the Porsche's exceedingly long legs. Despite all-wheel drive, its 400 bhp, combined with the tight course-induced understeer--made the experience less impressive than had the car run, say, Talladega.
There are faster biturbos out there, but I doubt they blend power and handling as seamlessly as the fly yellow rocket featured here.
PSI Motorsport RTS-1
PSI Motorsport's RTS-1 ("Road & Track Star 2001") is a road-legal 911 Turbo developed with PSI's racing experience and aimed at the owner who takes track days very seriously.
With an engine boasting 620 bhp at 7400 rpm and 601.5 lb-ft (815 Nm) of torque at 5500 rpm, the RTS-1 qualifies as a hyper-Porsche. Tipping the scales at 1,280kg (2,818 lb), it has a power-to-weight ratio of 1.06kg/hp (2.12 lb/hp) or 172 bhp/liter, so you would expect it to be fast. Against the stopwatch it records 0 to 100 km/h (62 mph) in 3.9 sec., 0 to 200 km/h (120 mph) in just 11.2 sec. and a top speed of 345 km/h (215.6 mph).
PSI Motorsport wanted its prototype to be light, stiff and rear-wheel drive only. As a team which prepares Carrera Supercup race cars, PSI knows that the Carrera 4, GT3 and Turbo shells are reinforced, so it based the car on a new Carrera 4 and removed all the 4WD components.
The outer panels are an interesting hybrid of current 911s. Wider arches were needed to contain the wheels and tires necessary to deploy 620 bhp, so the front wings and bumper/spoiler are GT3, and the rear wings and valence are Turbo with the intake vents removed and blended in. The fixed rear spoiler is a PSI Motorsport item, resembling a Turbo rear wing in the fully extended position. This sits on a new rear engine cover.
The wheels and tires are Fikse three-piece forged alloys in 10.0J and 12.5J x 18-in. sizes, shod with 245/40ZR18 and 315/30ZR18 Pirelli P-Zero Assimetricos. The low ride height comes courtesy of H&R coilovers with helper springs and race-grade Bilstein dampers valved for road and track use. The bigger anti-roll bars are H&R Supercup items, and the suspension is Rose-jointed. The end result is effectively a Supercup suspension set-up made more civilized for the road.
I drove the car from PSI's base near the Belgian and German border to Spa-Francorchamps, one of Europe's most highly regarded racetracks. In the process I saw over 180 mph (288 km/h) on the clock several times but was prevented from going any faster by slower traffic. However, the relative ease with which the car reached these speeds compared to the new GT2 I drove recently substantiated the monstrous power and torque claims.
Despite being handicapped by an extra 300kg, the RTS-1 is just 30 bhp short of the output of a Le Mans Porsche 962 sports prototype, more than sufficient to catapult the black 911 from the corners like a Patriot missile jumping off its launch rail.
It is very evident how a bit of sacrifice in comfort on the road can make a huge difference to a car's track behavior. Despite possessing much more power and torque, the relatively lower and stiffer RTS-1 utilizes its power coming out of bends better than even the mighty GT2. Even on street tires, its rear-wheel traction on the dry track is immense, a condition which normally sends a powerful street 911's nose wide in a bend. Here, with the relatively stiff semi-race suspension keeping the rear axle roll in check, the car is less affected by weight transfer, and the normally greater front roll stiffness of the basic 911 is toned down to make the car more neutral. This is used to great advantage when you want to slingshot out of a bend.
One of the great things about the firm suspension set-up, with its 30mm lower than stock ride height, is just how little attitude pitch, yaw and roll there is compared to a stock 911 on the track. On public roads, the ride is still good for a car that can control 620 bhp effectively. It is considerably firmer than a Turbo or GT2 and more like the original Carrera RS (964) in the way it squirms over short, sharp bumps. And another characteristic reminiscent of the RS is the way the ABS can be felt to pulse when you draw to a halt at a road junction on a slightly bumpy road. But, that front stiffness is not as bad as the RS. The ABS pulsed just once in this car where I remember the RS's system hitting the sole of my shoe several times in similar circumstances.
It is just as well that a 911's engine is behind doing the pushing, for when the motor is in full cry, its rapidly increasing thrust gives the impression that, if it were in front, it would rip itself from its mountings and head for the horizon on its own!
This level of power means you can reach phenomenal velocities in very short distances. Coming on to a short straight in third at 80 mph, with the next bend in the near distance, you light the afterburner and watch the horizon being reeled in as the speedometer rapidly swings round to 120 mph (192km/h) on approach to the braking threshold.
If you think a stock 911 Carrera has good brakes, these 355mm and 330mm race brake discs with massive Porsche GT2 four-pot calipers hammer out the word STOP! in capital letters. With its endurance helped by racing fluid, the brake pedal is firm, the responses incredibly positive and easy to modulate, and the result a very dramatic eyeball-popping loss of forward motion. In fact, unless you are used to very quick race cars, you will always start by braking too early. Even when you are used to the car, you will still surprise yourself with just how late you can brake from seemingly suicidal approach speeds.
There is no way one of the new Carrera 2/4 engines can be made to produce this level of power reliably from 3.4 liters, and the crank and crankcases are not strong enough to withstand the tremendous thermal forces. This is why PSI started with a GT3 3.6-liter engine and substituted new, low-compression forged pistons to give a CR of 8.5:1, which works nicely with the 0.9 bar boost from the twin KKK K24 turbos.
The two massive intercoolers are made in-house and flow 40-percent more air than the factory Turbo intercoolers. They are married in one casing perched above the engine in the time-honored 911 Turbo position. PSI felt that this configuration would work better in this application, and to further improve airflow to the intercoolers, PSI redirected the slats on top of the new engine cover to shovel more air into the engine bay.
The cams are ground to PSI's specification and are based on Porsche cams rather than being ground from fresh billets. They are used in conjunction with solid lifters.
The fuel pressure regulator is uprated to give 5.0 instead of 3.5 bar pressure in the system, and it feeds bigger fuel injectors. The Motronic ECU-605 is the GT3 unit, modified to fuel and spark this wild engine. Larger water radiators are used in front along with a big oil cooler. There is also an oil cooler for the gearbox, positioned just in front of the rear axle, under the flat floor panels. The exhaust system is all new, starting with a manifold made from Inox. The end pipes are bought in but were modified to match the system.
The GT3 short shifter and PSI aluminium knob help quicken the gearchanges, and the single-plate sintered competition clutch has quite a fierce engagement. But, if you take the revs up to 1500 rpm, there is no problem making a smooth getaway from rest.
On the road, another aspect of this mighty fast 911 becomes clear. Twin-turbo 911s of between 450 and 550 bhp behave fairly close to stock around town, with a steady idle and good low-speed tractability. To achieve its heady 620 bhp output, however, this car requires quite radical camshaft timing, which even the advanced Motronic engine management cannot completely tame. Thus, the car idles with the lumpiness reminiscent of tuned cars of the pre-ECU era. Out of first gear, however, the car does not like its revs to drop below about 2000 rpm or it protests quite noticeably. This is no fault of the Motronic ECU or PSI Motorsport's expertise. The simple explanation for this shunting is that so long as you have an injection system with an air-mass flow sensor, wild cam timing will create air mass oscillation in the inlet tracts at low engine speeds when the air in the inlet tract has insufficient velocity.
As the valve opens and the piston draws down the cylinder bore, the suction increases the velocity of incoming air. When the valve snaps shut, the incoming air bounces back, causing stalled flow and even standing waves in the inlet.
Imagine an air molecule being shot forwards, suddenly brick-walled and kicked back 2.0 in. before being drawn forwards again, and you get the idea. The oscillating air confuses the air-mass sensor, causing the mixture to go from full rich to full weak, hence the unstable running. Only a system that uses airflow sensing like Weber Alpha rather than air-mass sensing of this Bosch Motronic can get over this and calm down the effect of wild cams.
Of course, on the track or when being driven fast, there is no hint of this; it is only when you insist on letting the revs drop below 2000 rpm that the car begins to protest. If you are paying attention on the road, you would not let this happen anyway, as the sound and feel of the motor revving is so intoxicating. No surprise that it sounds like a distant 962LM racer or that there is the gentle "psst, psst" of the wastegates blowing off excess boost when you upshift.
The spartan interior certainly adds to the race-car feel. The cabin follows the traditional lightweight 911 formula with Recaro race seats and no rear seat. There is no rollcage in this car, but anyone doing a lot of track work would want one. The cage would add further stiffness to the shell, making the already great handling even better.
The PSI Motorsport RTS-1 was developed to be equally at home on both road and track, and it largely succeeds in both these roles. It is just comfortable enough to be a road car, although I could not imagine it as an only car. It is also stiff enough to deploy all of its 620 bhp on the track. It is a stupendously fast and remarkable balancing act with more than enough power to satisfy even an off-duty race driver.