Want more from your GT3? Our six top tips should be your first point of call
“Weissach has developed each generation of GT3 engine as far as it realistically can”
The GT3 remains a modern sportscar phenomenon. First revealed at the 1999 Geneva show as the homologation version of Porsche’s Cup 911, the GT3 is now in its sixth iteration. While the latest version is more tractable than ever, the GT3 is still a brilliant track car with an unbeatable combination of chassis, performance and responsiveness.
Yet, competition oriented though it is, most GT3S will be driven more on roads than racing circuits. This means the standard car has inevitable compromises in favour of street use. We show how this bias can be swung to the track in six key categories, without upsetting the GT3’S capacity to drive home afterwards.
1 Suspension and Geometry
This is crucial: even on a road car correct geometry set up is important, and before beginners spend anything on their GT3S, the first port of call is the fourwheel check. Only when the car is absolutely right, opines RPM’S Olli Preston, is it time to consider suspension upgrades. Those who track their GT3S regularly know that with the factory setting the car tends to roll off the tyre in corners. Greater toe-in helps to prevent this, and also brings vital stability during braking.
Simply lowering the GT3 does not bring automatic improvement – quite the reverse. Without some wheel movement the car will go into snap oversteer. A proprietary suspension kit, such as KW, has three-way settings, which are obviously more flexible than a two-way system, and allows a greater variety of circuits to be tackled. These kits can also improve ride for 996 and 997 GT3 road cars because they handle surface irregularities better.
Surprising as it may seem to some, there is not much you can do to GT3 engines. Specialists such as RPM Technik will tell you that Weissach has developed each generation of GT3 engine as far as it realistically can. JZM agree and warn against the temptation to change engine management software, despite the claims of improved performance from the chip purveyors. JZM cite the instance of 996s fitted with a chip from a well-known software merchant: these not only fail to improve performance, but mean ultimately that the GT3 ends up in the workshop because its vastly increased hydrocarbon emissions result in an MOT fail in the UK.
Another, often more productive, route to enhanced acceleration and response is straightforward weight saving. Switching from the standard steel discs to carbon ceramics can save 15kg per wheel. Olli Preston advocates the use of ceramic brakes purely from a retardation standpoint, telling us, “The technology is improving all the time and it’s worth switching to the latest materials available. An RPM client trying the most recent carbon ceramic set up was stunned, saying he had only ever experienced such retardation in a single seater.”
One route the specialists take to improve response is to substitute a lower final drive ratio. “For years, Porsche was obsessed with making a 200mph car,” says JZM’S Steve Mchale, “so gearing was far too high for most tracks.”
The final drive ratio is easily lowered, and a taller sixth can be fitted for cruising. For the differential, RPM Technik would advise use of the same harder friction plates as the Cup car, so deterioration does not become apparent until the need to do a routine rebuild of the diff is due. The specialists now favour a 40/60 LSD rather than 20/40: a diff that locks more on overrun will help to offset a tendency of the GT3 to spin on corner exit. Better friction plates also bring improved stability – with no wheelspin out of corners the rear is less likely to step out suddenly and provoke a spin. On the 997 GT3, the ABS intervenes to slow the faster wheel, and owners should be aware that this can cause heavy rear brake wear.
The specialists see the GT3 as a mechanical car. “It is not so reactive to aerodynamics,” says Mchale. “Spoilers will improve stability at a very fast circuit like Spa, but otherwise aerodynamics is not an area where it is worth spending money for the club track-day enthusiast.”
Porsche’s standard pipes and boxes are relatively efficient, but remain semimass-production items built to a price. Owners prepared to invest significant sums on lighter bespoke systems can expect some very minor improvements in power output on
996 and 997s, but more on the 991. The Akrapovic 400 pipe, for instance, not only saves 21kg, but also gains 23bhp more – and torque goes up by a similar percentage. However, one of the problems with modifying GT3 exhausts is noise levels. It is easy enough to end up with over 100DBA, which disqualifies the car at track days. A bespoke system like Akrapovic’s allows the driver to shut the sound amplifying valves all the time, which usually circumvents circuit noise regulations.
This will be especially important in 2018 with the arrival of periodic noise traps around the course rather than a traditional static decibel test carried out in the paddock.