SharkWerks 997.2 GT3 Modification and Tuning Guide
Whether it's your first 911, or if you've upgraded from the previous generation GT3, the MK2 997 GT3 is once again a brilliant platform right out of the box. It's a throughbred GT3 as every other one past and present is. For 2010 Porsche not only increased the displacement and power output a little by going from 3.6 to 3.8 (415hp to 435hp) but they also revamped the aero and improved the PASM suspension system to boot. For those of you coming from the 3.6 MK1 version you'll perhaps appreciate the additional aero/downforce at the track and added compliancy of the suspension.
Creature Comforts vs the MK1?
Many owners agree the MK2 probably makes for a better "road" going car than the MK1 requiring less reaction/correction input on bumpier surfaces thanks to the revamped PASM suspension. Throw in the fact that it has the newer PCM 3.0 with options for an improved NAV and/or BlueTooth/ipod and you can see that Porsche was trying to broaden the appeal of the car a little more. Need we mention dynamic cornering lights?
The MK2 is both more comfortable inside and over rougher terrain. The second generation PASM was designed to decrease the amount of correction/driver input required to deal with bumps through rebound. Unlike the regular 997S in 2010, the GT3 came with proper adjustable coil overs. You'll notice that in the rear there's a shorter style spring. Using a larger diameter coil with less windings that's capable of supporting the same load (rate) reduces unsprung mass. In other words the spring is lighter but does the same job as before on the Mk1. And as we've said before, unless you're interested in more serious competition level racing we see no need to replace the factory shocks and springs for general use. It's easier to ruin the compliancy and make the ride far less comfortable and erratic by switching out your coil overs unless you're comfortable with proper fine tuning.
As it sits, the MK2 997 GT3 is more than ready to drive daily if you're inclined (and we are!) and on the track on weekends. We were excited to see what if anything could be done to possibly improve upon this very special 911 and ended up with the first GT3 in Northern California with our Silver 2010 MK2 R&D project car. It's certainly fine to leave the vehicle stock, but for those of you (and us) that like a little more edge, precision and performance, there are a few slices of cake we found.
For the 3.8 GT1 based engine Porsche added vario-exhaust camshafts, unlike MK1 cars that only had the vario-intake camshafts. Previous generation owners will feel noticeably more torque than the MK1 down low in the rpm range -- again making it easier to deal with in traffic.
Seriously, what more does it need? What more could one want? Truthfully, there's nothing this car "needs" and it's as track-ready as a modern day car could be from the factory. But as most owners past, present (and likely future!) will tell you, there are a few good tweaks, pokes, and improvements that can sharpen this already-sharp tool even more.
We are often asked "What would you do if this was your car?" While there isn't really a correct answer for every person and situation, and this isn't meant to be an "Official FAQ", it is our guide to playing/experimenting with your GT3 based upon our experiences having owned, driven and worked with these cars over the years. We refer to the 2010+ 3.8L powered GT3 cars as "MK2" or "997.2" in this article. The "MK1" refers to the previous generation 2007-2008 GT3 models.
Factory Porsche OEM Upgrades
Porsche tends to get slightly stingy on the non-RS versions of the GT3, and although the marketing material talks about a "lightened" flywheel you still have a 25-pound lightened dual-mass flywheel in there. There's nothing wrong with that per se but wouldn't you rather have the single mass and truly light 14-pound (964-based) flywheel which is standard issue on the RS models? Gearing aside, a major factor in the quicker acceleration of the RS is indeed the single mass flywheel (see more on the flywheel options below).
The other difference you'll see from underneath is that the RS model had split control arms in the rear, meaning the arm has a section where shims can be used to add camber when aligning the vehicle. One could use the factory rear GT3RS control arms to replace on their GT3 model, but we have an alternative (RSS Tarmac Series, mentioned below) that is more cost effective and also includes solid bushings for better handling characteristics.
The air intakes on the MK2 RS and 4.0 versions are certainly more open and efficient than the standard intake carried over from the MK1 that comes on the MK2 GT3. They can be fitted (albeit very expensively) but you would need to modify the factory decklid to properly feed the air inlet and duct it correctly.
The MK2 GT3 wing provides additional down-force over the MK1 (it borrows a lot from the MK1 RS actually) but for a pretty hefty sum (in excess of $14,000) you can indeed fit the larger/taller RS wing. There are front Cup or RS lips that can also be used for more downforce in the front.
You'll find many of the GT3s were actually optioned with regular sport seats as shown below:
Other cars were optioned with the factory carbon bucket seats, which offer more versatility for the track by allowing for the installation of 6-point harnesses thanks to openings in the rear. These can be purchased from Porsche dealerships in the range of $8000 or alternatively ask around and see if other 911 owners (2009+) desire to swap with you. Quite often we have seen new GT3 or 911 owners (especially larger and taller drivers) swap the carbon fiber bucket seats with someone else for a pair of more comfortable reclining sport seats.
There is no better sounding factory 911 in stock form period. The 3.8 engine actually emits a slightly deeper tone vs the 3.6 on the MK1. This isn't your vacuum-cleaner-like 911 Turbo sound here. The GT3 sports three mufflers and even then squeezes out some truly epic sounds. European sound restrictions and laws tend to be stricter than anywhere else in the world so with a little effort you can pump up the volume. The only down-side is that the three-piece system weighs in at hefty 78 pounds.
You can simply unplug your flapper valve connector from the controller (your sport button inside controls this function to a degree) or plug the vacuum lines that attach to the side mufflers and enjoy a louder version of what the factory intended. It's free, easy-to-do and rather cheerful at that.
There are many exhaust products on the market and at SharkWerks we offer a few solutions ranging from rather wild to absolutely obnoxious. Our center bypass replacement (http://www.sharkwerks.com/products.php?pid=153) is what we found most daily driven, street and/or track cars use. You save about 14 pounds off the back-end with our replacement and get what we feel is a pretty nifty sound. It's louder on the outside but there's no drone/resonance on the inside so it's perfect for a long trip across the country (yes we really did do that) or for a date into town. Because you retain the side mufflers your sport button activation still works so you can simply turn it off and be as close to stock as possible.
See the difference here:
For the track-heavy users we also offer a complete replacement race pipe (http://www.sharkwerks.com/products.php?pid=339) which saves about 55 pounds from the tail (a good thing indeed) but it can be heard for miles and miles:
It's best served with a helmet, the sort you'd need to wear at a race track with no sound restrictions. On the plus side when you're not ringing people's ears you do remove a bunch of cooped up heat away from those fat rear tires when removing the side exhausts. We have found that such a drastic change in back pressure robs the car of a small amount of torque down in the low-rpms (below 3.5k). This usually isn't important for the RPM ranges that track cars and spirited drivers use and some of that power can be recovered (along with the throttle response and additional top-end power) with our software tuning.
The stock tips are fine and dandy but for those of you that want something larger and more pronounced we offer our larger 88mm ceramic coated tips:
The Factory has Titanium!?
Indeed they do use titanium on the MK2 GT3RS center muffler, but it's very much a non-starter for this GT3. The single-wall thick Ti center section is actually prone to failure on the 3.8RS and doesn't really change the sound all that much either. It's lighter by about 15 pounds but your wallet will be a lot lighter than that - to the sum of $3000.
Headers & Catalytic Converters
Many of the factory cup cars sport almost identical header designs as what's found on the stock car so you're starting with something pretty spot on. Could it be better/improved? Certainly but at what cost and drawbacks? You'll be changing heat ranges the ECU reads, not to mention back pressure. All of these have an impact on what ignition maps your ECU calls for which can negatively affect power and drivability. Freer flowing headers sound good on paper but we usually see a low-end torque loss and in some cases a loss of power. Back pressure drops on a naturally aspirated engine do not produce the same level of gains/advantages as on a turbo engine. Since the headers and cats are a single piece on these cars, the oxygen sensors that provide the ECU with data can't just be moved around or ignored, either. They're vital to how the car will actually run and although you can make more power with less dense catalysts (200 cell versus 400 cell for example), we have seen many aftermarket cats break-down, come apart and fail. A check engine light is to be expected (even without visible failures) and something one should be prepared to face with this direction. The overall volume of sound will also increase.
We are still experimenting with freer-flowing cat/header designs on our MK2 RS, but for the MK1 cars and with our 500 HP 3.9L engine we are still using the stock factory header/cat system and have not found it stopping us yet! They do not cause a check engine light and to our knowledge do not have a high failure rate even when tracked extensively.
One interesting factory-made alternative is the 4.0 header/cat system. The headers themselves are identical however the catalyst element is reduced from 400 cell to 300 cell. It should be much more reliable than most aftermarket brands, but it's pricey...
If you plan to change the headers/cats on your car, you should consult local and federal emissions regulations, as tampering with this equipment is not legal for street use in most regions.
The 997.2 GT3 intake box is actually the same as found on the old 2004 996 GT3 and is derived from the 2001 Turbo. It's not perfect but it seals very well which is important. We have seen, tried, tested and even R&D' our own variations of intakes with cone filters et all both in single and dual-format but we were never able to produce real horsepower gains. We tried using different designs during our 3.9L engine program development and even at that level we did not find the factory airbox to be restrictive or particularly lacking. Most of what we have seen on the market tends to cause more turbulence but also sucks in hot-air and raises the intake temperatures. The ECU feeds off of sensor data from the intake and increasing the temperatures leads to ignition timing being reduced, which means the engine will produce less power. There was very little audible change either. If you're looking for more power the intake isn't where you're going to find it.
The factory does offer a solution in the form of the slightly improved 3.8 MK2 GT3 RS intake with a second inlet and dual feed through the decklid. An even more expensive option is the factory 4.0 airbox which sports two sealed conical filters in an extremely beautiful carbon box which is north of $6000. That alone won't suffice because you will also then need to modify your existing factory decklid to feed/funnel air to the second inlet in the box. Not exactly easy to do nor kind to the existing decklid (especially if it's the more expensive RS).
If you must tinker with your airbox we have used both the K&N and BMC filters in the past. We can't say you'll see/feel any difference but at least it does breathe better than a paper factory filter.
If you plan to change the intake air box on your car, you should consult local and federal emissions regulations, as tampering with this equipment is not legal for street use in most regions.
As a MK2 GT3 versus RS owner, you might feel a little short-changed by the latter's higher HP output. Even though it's never easy to eke out more power a high-strung GT3 engine, we spent several weeks and months (multiple dyno days/sessions) fine tuning our 2010 car with the EVOMSit tuning tools. A tremendous amount of time was spent fine tuning the software with 91 and 93 octane fuels not just on the dyno but on the street too. It's not just peak power but the drivability is also improved and much time was dedicated to the E-gas (electronic throttle pedal) settings which have been optimized in both sport and non sport modes. The improved throttle response in both modes provides a snappier throttle response as well as smoothing out some of the small dips.
With software only, the 2010 GT3 went from 392 RWHP to 404 RWHP at the peak. The car gained about this much horsepower for most of its RPM range. The car gained over 10 ft-lb of torque at its peak around 6600 RPM and more torque throughout the RPM range. With the exhaust and software, the gains were higher, bringing it up to 414 RWHP at the peak (22 RWHP net gain), more torque at the peak, and a large gain in torque between 3700 and 5400 RPMs.
You will notice a drop in torque at lower RPMs (below 3500) with the Track exhaust due to the greatly reduced back pressure, but there is a significant increase in torque after this point and horsepower throughout the RPM range. We still recommend our Street Bypass setup for most owners for several reasons, including that it does not lose torque like this (and it doesn't set off car alarms, cause your dog to run away, etc.).
One can also customize some of the settings including adding in the ability to left-foot brake. The throttle body will no longer closed when touching the gas and brake simultaneously.
The OEM ECU features what we call IST (Intelligent Switching Technology) that allows for automatic switching of ignition timing maps based upon input received from other engine sensors. The EVOMSit ECU tuning utilizes the multiple OEM ignition tables in progressive stages, which can optimize safe performance based upon outside conditions and different octane fuels. The ECU automatically switches to the best-suited ignition map creating an automatic “race mode” if race fuel is utilized. We often get asked if is worth running better gas. The answer is always absolutely! The ECU even in stock form can take advantage of it.
Not only are the power gains and overall performance impressive but we were able to improve the power while utilizing 91 octane fuel.
If you plan to modify the software on your car, you should consult local and federal emissions regulations, as tampering with this equipment is not legal for street use in most regions. Please read this page for more information.
Everything changes with the MK2 GT3 with respect to the wheel choices. Out with regular 5-lug wheels and in with Porsche centerlock system, which if not used correctly can certainly lead to issues. There is a very specific torque procedure (ask for the update from your Porsche dealership) and be sure to buy a sufficiently long torque wrench and have a spare person handy to sit inside and stand on the brakes while you loosen/tighten the wheels. The most important thing to remember is to get the wheel safety lock properly secured before you go ahead and torque the wheel tight.
The MK2 GT3 wheels are stunning aesthetically and they're reasonably light too (rear shown below)!
For those of you that do want to change them do try not to "add" weight and stay well away from 20-inch wheels. Your highly tuned suspension will thank you. We offer several lighter-weight forged options (we even have our own brand Magnesiums if you must) that we have bought and tested at the track that have held up over the years. We prefer to stick with our two long-standing partners (over 7.5 years) HRE and Champion Motorsport. Pick your flavor and go. From HRE we'd recommend either the single piece Monoblok series or the motorsport-derived Competition series. Shown below is a rear HRE P40S wheel:
And it's lighter too (by nearly 7 pounds per rear wheel):
Currently featured on many pro and club race cars is Forgeline. We have newly introduced their wheels into the SharkWerks line-up. We have found their wheels to be the lightest and most aesthetically pleasing of all and hence we run their forged 19 inch GA1-R on our own 2011 GT3RS 4.1 car:
The more track-minded you are, the more likely you will end up with a second set of wheels. One set for the track and one for the street. For those of us that drive the cars daily and/or in the rain, one set could be outfitted with a non R-compound tire such as the Michelin Pilot Super Sport. It tends to last longer as the tread-wear rating is considerably friendlier.
Want to go faster still and have an even better choice for race rubber? Then go with an 18-inch set up. Something like the HRE R40 race wheel which even fits over the PCCB caliper. It's both light and strong at 17-20 pounds and is currently used in real-world racing, rallying etc... The 18-inch wheel gives new options for tire choices.
Just say no to 20s. Get that idea out of your head. It won't look good. It won't ride well. The geometry and suspension was never set up for that sizing and we never put wheels larger than 19-inch diameter on the GT3.
Got steel brakes? Brilliant. They've been upgraded to larger 380mm pseudo two-piece rotors. Got PCCB's? Also bully for you (albeit with a slight twist). Trying to improve upon the factory system is like trying to take a top tier MMA fighter aside and saying, "I really like what you got and I need you to go more than 5 rounds". It's not something that's really necessary, nor is it easy to do. The factory brakes are world-class, make no bones about it. If you've come from any other Porsche wait till you put your foot into these -- especially PCCB's.
For a pure street car the PCCB's should be left alone. It's just not something one really needs to tamper with unless you're using the car extensively at the track. For steel brakes, you can certainly try running more aggressive pads but be prepared to change rotors (and induce even more noise) more frequently. When it does come time to change rotors a firm favorite is the two piece GiroDisc rotors (http://www.sharkwerks.com/products.php?pid=194) which are not only a few pounds lighter but have better cooling properties thanks to their slotted design and an aluminum hat which you re-use.
Over the years we've only seen a few GT3s, (each in the 50-60k mile range and driven hard with a 3.9 to boot) that have seen the calipers start to fail. In those rare cases we've switched to the Brembo GT system with great results (front: http://www.sharkwerks.com/products.php?pid=358 / rear: http://www.sharkwerks.com/products.php?pid=359). The 380mm front and rear kit can be set up with either drilled or slotted rotors. The rotors and calipers are lighter than the factory steel brakes and rotors.
Tracking with PCCB's
It's generally not a great idea to use the PCCB's if you plan to track more than a few times a year or at medium/higher skill level. The rotors will simply not last long enough to be economically viable. Sadly that $8800 option is usually replaced with a $5000 two-piece steel rotor set up that we provide our track customers from Brembo. Their Type III rotor kit (front: http://www.sharkwerks.com/products.php?pid=199 / rear: http://www.sharkwerks.com/products.php?pid=360) allows you to re-use those same yellow calipers in the front and rear but with 72-vein rotors (double that of standard) and intricate slots they've managed to survive well into a season even on higher HP turbocharged GT2 cars... let alone GT3s. A superb option/alternative and the only draw back is the use of a narrow annulus brake pad in the front. Because you're no longer afraid of destroying your PCCB rotors you can opt for more aggressive brake pad combinations and replace just the outer rotors (retaining the aluminum hats) when needed for a much cheaper price than ceramic. In the field, this set up has been used for One Lap of America on GT3RS', Club Racing with 3.9s and general Driver's Education events with great success. Your hand brake still works, unlike some other brake kits. A cheaper alternative is the 380mm Girodisc which we also offer.
We like to Mov it - Aftermarket Ceramic Replacement
A few West Coast GT3'ers have swapped out their factory PCCB's for a ceramic alternative from Mov' it. At $25,000 they might seem expensive but factor in replacement factory rotors vs. only having to buy these once (they are guaranteed to last the life of the car), and if carbon ceramic rotors are how you want to track then these are proven to last much longer than the factory option. Other than cost they are slightly larger, a tiny bit heavier and oh yes expensive.
In terms of improvements start with better cooling- brake ducts from the Gen2's are often used in the rear, for example.
The stock suspension on the GT3 is considered to be the best OEM 911 suspension available, and therefore it's ready to drive on a track or enjoy on the street with no changes. Do at least check on the alignment since it tends to be delivered from the factory somewhat erratically/inconsistently set up. If you want to go with a fairly aggressive set up off the bat you can use what Porsche has termed their "track setting" in the back of your manual. It's a good starting point.
Coilover Suspension - Springs and Shocks
The OEM suspension on a GT3 has a coilover system, meaning the car has adjustable ride height and an excellent sport shock from the factory. The shock has the "PASM" feature (Porsche Active Suspension Management), activated by using the shock button in front of the shifter. This button enables a stiffer dampening/rebound setting on the shock (via On/Off settings) which makes the handling firmer for flat roads. It will make rough roads appear bouncier, something that Porsche addressed on the MK2 GT3 by making the car softer (hence faster at rough tracks including the Nürburgring in Germany).
The stock coilover suspension, designed by Bilstein, is completely sufficient for most street drivers and track use, rarely being a concern for even very fast drivers who do not adjust their suspension meticulously for the fastest lap times. Although we generally recommend leaving this stock coilover system in place, as it's far easier to make the car worse than it is to make it better we have played, tested and lived with indeed better alternatives. First generation GT3/GT3RS' and their PASM have often been critiqued by both the press and owners for being too harsh and reactionary over variable terrain. The second generation PASM was much improved as far as compliancy is concerned and indeed for the 4.0 was darn-near considered perfect (also a possible upgrade). Indeed for canyon carving with uneven surfaces the the suspension can overly-react in terms of rebound (especially) and compression with undesirable results such as constantly having to correct/counter steer with compliancy suffering.
With excessive driving on rough terrain or track use, the stock shocks will eventually wear out, either by the shock body's shaft bending or the shocks simply wearing out. The best options when this happens, we've found, are to replace the OEM system with another set of OEM components or indeed to dispense with PASM altogether and go straight for the Motorsport Designed Bilstein ClupSport double adjustable coil over system. With narrow-band ranges for compression and rebound and acute adjustability for both compression and rebound we have found that by fine tuning we are able to get much-improved compliance, consistency and along with a more confident ride even on our own former Generation 2 PASM car. Proof that analogue can be better than digital after all. We really feel this ClubSport system is a game changer for 1st generation 2007-08 PASM owners that feel like they get "beat-up" and have inconsistent results when driving over variable terrain.
Suspension Links and Toe-Steer
The upper rear suspension links (2 per side, 4 per car) on all 997 models feature neoprene bushings and are non-adjustable in length. The RSS variant adjustable links provide a long lasting, quiet solution to both of these problems by giving adjustable length and monoball bushings on either end. These bushings stiffen up the handling and feedback on the car, giving quicker handling response and more direct results when you turn the car. The adjustable length helps to set the alignment to factory or race specs on modified cars. More info: http://www.sharkwerks.com/products.php?pid=204
One other issue with the rear suspension is the toe-steer link, that directs the toe-in/out angle of the rear wheels under cornering. The RSS replacement Toe-Steer kit also includes a monoball inner bushing, giving further tightened handling and feedback as it replaces another neoprene bushing. The length is adjustable for toe adjustment on the alignment beyond factory and the locking plates ensure that the toe-angle does not swivel and change as the suspension arm travels up and down with bumps, unlike the factory piece. More info: http://www.sharkwerks.com/products.php?pid=205
There are two choices for stock engine mounts on the MK2 GT3. One is the standard hydraulic engine mounts, and the drivetrain which will move independent of the chassis during acceleration, deceleration and cornering. This movement can upset the balance of the vehicle and create negative handling effects. The RSS engine mounts minimize these effects by utilizing specialized polyurethane bushings which offer a firmer, more direct driving feel with optimum feedback. This upgrade will not adversely affect ride quality or cause knock sensor issues commonly associated with solid engine mounts. More info: http://www.sharkwerks.com/products.php?pid=336
For those of you with the optional Porsche Dynamic Engine mounts, those are best left in-tact. We can't say we notice a world of difference but the fact that they supposedly "harden" during acceleration is at least useful.
Control Arms, Thrust Arm Bushings, Pivot Bushings
The GT3 has an adjustable front control arm due to its split design, meaning the negative camber on the front wheels can be adjusted using shims. The rear however lacks this component (it is standard on the GT3RS model).
If you plan to track the car often, you will most likely want to adjust the rear negative camber and will want adjustable rear control arms.
We recommend the RSS Tarmac Series Control Arms (http://www.sharkwerks.com/products.php?pid=322) for a couple of reasons: they're actually priced better than factory rear arms and they also include steel monoball pivot bushings and aluminum thrust arm bushings. The factory arms have two locations (on either end of each arm) where Porsche opted to use a neoprene bushing, to quiet and dampen the street driving. The RSS arms hold up well with mileage (we have seen some with 30,000+ miles of mixed driving now) and are very quiet despite these metal bushings.
The result is better feedback and more direct handling; a stiffer setup that won't cause headaches and back pain from extra jolts. Yes, these parts are okay for street use and it's unlikely you'll complain about the extra noise.
An alternative is to replace the neoprene bushings in your stock control arms, but this would only make sense in the front (as the rear would still not be adjustable) and due to the labor involved and the permanent nature of this modification, we find it's better, easier and cheaper to simply swap them out.
The stock sway bars on the GT3 have three adjustment points for low, medium or hard settings in the rear and five adjustment points in the front. We recommend keeping these stock, and modifying the settings based on your driving style, alignment setup and track conditions. A common mistake on the sway bar setting is to set it "full hard". This can result in excessive understeer (front), oversteer (rear) or a lack of traction at one corner. Typically a softer setting is recommended when dialing in the suspension.
Lift Systems and Daily Driving the Ultra Low GT3
For those of you that intend on driving the car every day, everywhere, the front lip and nose tends to take a beating. Getting in and out of driveways is hard enough on a normal 911, let alone a lowered GT3. For the MK2, Porsche actually addressed this by offering an optional pneumatic airlift system. If installed then leave it be.
For those of you without the factory noselift, there is actually a solid solution from TechArt . In fact, the TechArt Noselift system is not only faster but it also raises the nose even higher than the factory MK2 kit by an extra inch (a total of 2.5-inches). This makes it more convenient and faster to navigate out of gas stations, parking structures with "Black" Ski Slope-style driveways/entrances/exits. The high cost of the system does mean you need to factor in just how many lips you can buy for the price of entry though. Over the years this system has proved to be quite popular and we've installed them on GT2's, GTRS', MK2 GT3RS' and many Turbos.
An absolutely favorite modification in these waters. How can those titanium rods and other light weight internals possibly spin up/down as well as an RS that has a 50% lighter flywheel? The non-RS versions of the GT3 are outfitted with a quieter and heavier dual mass flywheel. That way the effect of transmission sizzle, rattle and reverberation is limited both inside and outside the car. Yes it's quiet, friendly and docile this way but you're leaving acceleration, enjoyment and performance on the table by staying with a dual mass. That GT3 engine was designed to be revved and the factory provides a solution from the factory RS and 4.0. It is worth noting that the latter kit is more expensive and certainly able to last longer with a beefier pressure plate. There have been many instances recorded from overly aggressive down-shifting in track-like conditions where the straps on the pressure plate have failed with the original 3.8 pressure plates (which are riveted together). The 4.0 pressure plate has straps that are bolted together. We recommend the 4.0 kit (http://www.sharkwerks.com/products.php?pid=154) and in fact Porsche dealers have superseded the 3.8 parts for these reasons. For a full race car some folks have switched to a Tilton multi-disk set up but this is neither practical nor friendly for a street car. The words "get a cup car" come to mind if you're racing.
Along with the clutch, ring gear, pressure, plate, flywheel et. al you should also upgrade to the GT3RS crank pulley, bolt and washer. Early cars sported different pulleys and in some cases were not sufficiently torqued from the factory and came loose.
LSD - Limited Slip Differential
The factory does provide an LSD on the 997.2 GT3, but it's a rather weak clutch pack and materials. More often than not, we find low mile GT3s that have been tracked a few times have lost any use of the factory limited slip differential (essentially running an open diff). It's certainly been documented as a weak point in the car and for those of you regularly going to the track this is an area we suggest beefing up.
When removing the transmission to do a LWF conversion we also suggest saving on labor/removal time and performing some sort of LSD upgrade. Most popular with us is the 60/40 split from Guard. Don't go overly aggressive on a street car as you can start to get the car walking into other lanes when letting off the gas...
The GT3 and/or GT3RS body/aero are both absolutely functional and visually gorgeous. There should really be a "Do Not Tamper" sign before changing any aero bits on these cars. However, the front lips get munched a lot. Replace the standard GT3 one with the more expensive RS one if you must or use the Motorsport CUP lips which are also popular and more aggressive.
A common complaint for daily driver GT3s/RS' is that the front end/lip scrapes and one can't get out of the driveway easily. We've had customers who literally have contractors out to change their driveways in downtown San Francisco to narrow the slope or you can keep on buying lips. It's disposable if you will.
As stated above you can adorn the rear end with a factory RS tail. It fits and does so very well however at sky-high price. We have seen some after-market looking RS tails before and although the price is about 1/4 of the real thing don't expect factory style fitment/finish/quality.
Here's an example of the RS tail/wing:
One nice addition from the factory to the MK2 vs the MK1 was radiator screens to protect your rads in the front. Now where did Porsche get that idea from? Either way it shows that sometimes the after-market really does get it "right" and Porsche made the necessary change. One modification that seems to have become popular is the addition of the 4.0 front canards which cost a pretty penny but we will let you get away with that one!
RMS Oil Leaks, Coolant Failures and Other Concerns
The GT3 is well known to be a very reliable car, especially considering its performance and how it's intended to be driven. However, it does have a few reliability concerns that will often be mentioned by owners and enthusiasts. The cooling system on the cars is completely sufficient for track use and the car can be raced from the factory without worrying about overheating, but it has a couple of flaws that need to be addressed. This is the case with all modern GT1 engine-based Porsches: 996 GT3, 997 GT3 and GT3RS, 997.2 GT3 and GT3RS, 996 Turbo and 997 Turbo, all GT2 models.
Rear Main Seal Oil Leaks and Smoking on Cold Startup
The GT3, by design, has a rear engine seal that will leak oil. This will leak especially after the car has been sitting for several days or longer. It is very common and considered normal by Porsche North America. The amount of oil that leaks varies, but it is typically a few drops per day, after a couple days of sitting. This is due to the way the seal works under vacuum, and while the engine is running it should not leak oil. Once the vacuum is released and the car is shut down, it will eventually begin to leak.
There are a couple ideas on how to fix this, including other engine seals (from the 996 Turbo for example), however nothing has been 100% proven effective to work. The best solution seems to be to drive the car regularly and accept the fact that it will leak when you do not drive it. You can try replacing the seal if the leaking becomes excessive.
On cold starts, especially after the car has been sitting for some time, the car will emit excessive clouds of smoke from the tailpipe. This is considered normal and is due to the way the oil recirculates in the engine. A pool of oil will form in the engine when it is not running. This oil burns and smokes upon startup after the car has been sitting. There is no fix for this and it will not harm your vehicle.
Coolant Pipe Leaks / Catastrophic Coolant Pipe Failures
One major concern, especially if the car is being tracked or driven at high speeds, relates to the six coolant pipes running from the heat exchanger, water pump and coolant manifolds. These pipes are sealed into their homes using a rather weak adhesive, which tends to fail at unpredictable intervals. The result is a rapid spilling of nearly five gallons of slippery coolant directly over your rear tires! Many owners have reported high-speed crash and spinning incidents due to this problem, least of your worries would be that you could overheat and damage the $25,000+ engine in your car.
There are a couple of methods for repairing these coolant leaks, typically either pinning or welding the tubes in place and re-sealing to ensure a permanent fix. The real problem is that the hoses are ejecting from the engine, not that they are leaking. The pin technique is our method, and we have used it on every vehicle that has come in for an engine rebuild with no failures to date. Welding may be an option, however the housings being welded to are porous cast aluminum and the tubes are ultra thin - an awful combination that as we have witnessed may result in porosity / micro leaks and even "clean" looking welds may be ineffective at preventing leaks, even if they fix the ejecting tube issue. More information on this process is available here:
We recommend removing the engine from the vehicle to perform this task.
There is one other cooling concern on these cars: two small plastic tubes on the engine that tend to crack due to ultra thin walls. This happens especially often on higher-mileage or tracked cars. These plastic coolant elbow pipes run to the oil cooler (aka heat exchanger). The stock molded plastic tube will break down at the o-ring slot (its weakest and thinnest point) over time and mileage, causing a crack to appear spilling coolant. Eventually the whole engine will need to be removed in order to replace a cheap plastic tube which could cost thousands of dollars. This issue has also been observed on the 997 Turbo model.
A razor blade is used to show where the leak occurs:
For this reason we created a stainless steel pipe with machined billet end to permanently replace the cheap plastic part. The engine must be removed in order to install these so we recommend performing the "coolant fix" at the same time or replacing these whenever an engine rebuild is in progress.
You can view this item on our site here:
Seats, safety and track prep
In RoW (anywhere except the USA) the GT3RS' were outfitted with skinny Carrera GT fixed-back buckets. In the US we got either the carbon GT2 style buckets with thorax airbags or the heavier regular sport seats. For track work the later need to be replaced before attempting to use any harness/restraint system. Those of us that are extremely skinny and don't mind paying the extra $10-15k can outfit a GT3 or RS with these Recaro made buckets. They're super light (see below) but not exactly for regular sized folks.
For most of us the MK2 carbon foldable bucket seats (found also in the 2008 GT2) are a great option (though still expensive expensive at $8000) and fit in just fine. They do seem to sit higher than you would expect for a taller person. A helmet could be tight...
For more serious track work, look into Recaro/Sparco alternatives. Be sure to get the correct bracket/hardware and leave enough clearance for your head and helmet.
RS' in Europe or Clubsport GT3s came with various versions of the factory rollbar. Not so in the US. There are a few good ways to address this and should you need/want to install 6point harnesses, we recommend Schroth Profil II pull-down with HANS capability. Also remember to plan on a good solution for the sub belt - we suggest either using the factory 996 GT3 sub belt bracket (modified to fit), or a Brey Krause alternative and/or eye-bolts in the chassis (you would need to drill holes into the chassis for the later option since US cars did not come drilled). It is possible to import the factory Tequipment roll bar or RS half-cages can be imported from Europe.
In the US it's much easier to go with after-market bolt-in roll bars such as the ones we use from RSS. A starter or analogue of the factory Tequipment bar is the 901 shown below:
For the GT3s the most popular is the 930 which bolts into the strut tops at the rear of the car (an improvement over the Tequipment). There is also a more serious Chromoly made weld-in option in the form of the extra-braced 931.
It's important to remember that none of these solutions are welded in nor do they provide the same level of safety as a professionally built and structurally improved full roll cage. If you intend on more serious track events or club racing, then we suggest finding an experienced cage builder. In our area we use TC Design for example.
These are usually welded to the chassis and do not have the points bolted into seat belt mounts etc... that could sheer. More serious track nuts tend to refer to these "bolt-in" roll bars as "jewelry" or "glorified harness bars". For driver's education they do the job just fine though.
For those of you that do not want to have a roll-bar you can actually use a Brey Krause harness bar which is easily removable and less intrusive.
SharkWerks Recommends (for Street Use)
- GT3 bypass exhaust
- EVOMSit Software
- Toe-steer kit & locking plates
- Adjustable rear links
- Lightweight Flywheel
- Coolant Pipe "Fix"
- Shark Werks Coolant Pipes
SharkWerks Recommends (for Track Use)
- GT3 bypass exhaust or SharkWerks GT3 race pipe for tracks with no sound limits
- EVOMSit Software
- Toe-steer kit & locking plates
- Adjustable rear links
- Lightweight Flywheel
- Steel brakes (if tracking regularly and using PCCB brakes)
- Harness bar & safety harnesses
- RSS engine mounts
- Coolant Pipe "Fix"
- Shark Werks Coolant Pipes
- Zinc-based racing oil such as Mobil 1 Synthetic Racing Oil
Items we would NOT recommend changing
- Headers / Catalytic converters
- Rear wing or body panels except to OEM parts from other models
- OEM Radiator and cooling system (except coolant pipes that fail)
- OEM Oil cooler and oil system
Recommended Forums & Links
Rennlist.com - The most active forum for GT3 owners, a wealth of information and especially for track use
6SpeedOnline.com - A great site for street enthusiasts and beginners to the GT3
Teamspeed - This forum has a wide audience including international GT3 owners and many news stories about upcoming GT3 models