On to some tech info on the cars for those who are interested.
All cars run a common race chassis and common safety cell or cage assembly onto which the common suspension parts and various body structures for the different makes are attached.
5.0 Litre V8 Engines are unique to each manufacturer and intriguingly we have the American based pushrod motors from Ford and GM Holden running competitively alongside the four valve Nissan OHC mill. The engines are controlled brilliantly by having control camshafts, max 10:1 compression ratios and Rev limits of 7500R/min.
Engines do have freedoms to move power bands & shift the grunt to a degree, up or down the rev band but all engines are limited to a max Total BHP across the rev range (will explain how they do this in future posts)
Racing fuel is a 85/15% blend of Ethenol and Petrol (E85) with a Ron Octane of 115
The combination of specs noted above make for excellent power (630 to 640 Bhp for all engines) and brilliant reliability. Engines do roughly 3000km between teardowns ( they call servicing) and most components last to 6000Km.
Gearboxes are in fact transaxle assemblies mounted at the rear of the car and have sequential shift patterns like a motor bike. Axle ratios are stipulated for the various tracks by the race organisers.
Aerodynamic performance is homologated on each body type allowed into the race programme. Both downforce and aero are known factors and all car types go through extensive testing to ensure similar performance between brands.
Tyres are control tyres supplied by Dunlop and available in two compounds
The power and aero achieved allows maximum speeds of 300km/h at Bathurst and that is in a bend called The Chase….spectacular to watch the cars dancing through that right hander.
Some of the adjustments able to be controlled by the driver include fuel mixture (lean, rich for fuel saving), roll bars front/rear and brake balance.
All the above may sound controlling but necessary. The regs provide the two aspects absolutely critical to good racing, similar performance and first class reliability. With those two aspects in the bag it eventually comes down to car set-up, driver capability and to a small degree, the ingenuity of engineers on minor areas allowed on engine freedoms …..and that is exactly what we see on the track. At the last race at Sandown, qualifying had the top 24 cars 1.06 sec apart…..