Road v Race - HSV GTS

It would have been excellent to have a Commodore Omega on test here, purely as an anti-benchmark, to demonstrate how far above it the bar is lifted by cars like the GTS. As things stand, in the present company, the GTS's performance is ... mundane. Like not being a medal-winner in an Olympic final.

The W427, which weighs 45kg (two percent) more than the GTS, understandably romps away on the straights. You'd expect that of a vehicle with an extra 58kW and 90Nm. But the GTS's wheel/tyre package is identical to W427's (245/35ZR20 front and 275/30ZR20 rear), so why the big in-corner difference?

The GTS is significantly slower than the W427 in four of the five cornering manoeuvres around Calder, across a wide range of speeds, and almost line-ball on the fifth (turn one, 64.0km/h versus 64.1). The 427's cornering edge is probably due to its suspension tweaks - lower ride height, unique MRC calibration, different spring rates.

The GTS is six percent slower through the first dogleg, four percent slower through both the kink and the second dogleg, and three percent slower through turn two. This relativity in the cornering stakes is reflected in the peak lateral G numbers recorded around the track - the GTS generates five percent less lateral G in left handers and eight percent less to the right.

It's worth noting here that speed and cornering load aren't directly related - cornering load varies with the square of speed, so the differences in generated cornering load between the GTS and the W427 in turn one, dogleg one, the kink, dogleg two and turn two are: negligible, 12 percent, eight percent, eight percent, and six percent, respectively. Small changes in speed make big differences to cornering.

Interestingly, there's less of a gap between the pair in steady-state corners - the two sweeping right-handers at either end of the main straight - and a more profound difference in the transient cornering (both doglegs and the kink). This is probably due to the ability of the W427's unique MRC settings and how it adapts to keep the chassis under control. (1800kg is a lot of mass to nudge one way and then the other through the kink at 150-odd km/h, even with such big tyres gripping the track.)

And don't be fooled by the lacklustre peak brake application number (0.9G versus about 1.0 for both Ford road cars). The GTS (and W427) didn't brake as hard or as late as either Ford. So the stops took fractionally longer (about 0.7 seconds) - which reduced the peak brake load. The average deceleration under brakes on the main straight was 0.58G for the GTS (versus 0.53G for the GT and 0.65G for the F6). On the back straight the numbers were 0.63G peak/0.91G average (GTS) versus 0.60/1.05G (F6) and 0.67/1.08 (GT). The different braking characteristic could be either a Holden/Ford thing or a Tander/Richards thing.

Price $78,170
Engine V8 (900), ohv, 16v
Capacity 6.162 litres
Bore/stroke 103.25/92.0mm
Compression 10.9:1
Power 317kW@6000rpm
Torque 550Nm@4600rpm
Transmission 6-speed manual
Kerb weight 1829kg
Power-to-weight 173kW/tonne
Tyres Bridgestone Potenza RE050, 245/35R20 (f); 275/30R20 (r)

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