GT3 tech

Want more from your GT3? Our six top tips should be your first point of call

Total 911 - - Contents - Writ­ten by Kieron Fen­nelly

“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.

2 en­gines

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.

3 Brakes

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.”

4 trans­mis­sions

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.

5 aero­dy­nam­ics

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.”

6 ex­hausts

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.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.