Hi everyone,
Spring rates of 6kg/4kg used were as per "Circuit/Road" spec Group 4's to suit road tyres. If we were running R spec tyres we would reccomend and fit "Race" spec spring valve combination at around 7.5kg/5.5kg. High performance road and or R spec semi-slicks can not generate enough grip to warrant spring rates in excess of 8kg, particular when used on a relatively poor surface track like Wakefield.
For what it's worth, most cars we test and develop with at Wakefield will see a 1.5 to 2 second per lap improvement when using R spec tyres vs performance street tyres and another 2 seconds for slicks. For example, our P-Rex XRD (Tarmac rally setup '97 STi with pro driver) holds the club record on slicks at 1:05.80 using Michelins, our P-Rex I (99 WRX with gifted amateur) had a class win at 1:08.27 using Dunlop D-01's. Best case for similar car with performance street tyres using a good setup is late 1:09's or low 10's.
As a rule of thumb, expect a 2 second reduction per tyre class change. So I would suggest a DC2 VtiR on R spec with a good driver should be able to get into high 13's to low 14's if properley setup, particularly with some extra power and better brakes.
Apart from all the above, we did not post lap times as an absolute or as a challenge to others. We do not use race drivers for testing road setups and nor do we compare results from different days when weather and track conditions can dramatically vary the results. Our testing is about acheiving predictable handling with consistency while logging maximum sustainable G's and handling bias. Its also done primarily for road/weekend race hybrid product which is our main market. We can and do prepare some tarmac rally cars but these are not driven on the road and can be designed more toward a race biased compromise.
Best
Jim
Whiteline
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