PCGB Knockhill Track Day - Going for Gold
With a total of 35 cars entered for the annual PCGB track day at Knockhill, and the weather forecast turning out far better than expected with dry, sunny conditions tempered by a cool stiff breeze, any rain showers coming along would soon dry out. And so it proved.
In my case it was prophetic that the wrist bands for the Advanced Drivers group at signing-on were coloured gold. As things turned out, the day could not have gone any better for me. Having completed 20 or so dry laps at Knockhill the previous Sunday, I arrived at the circuit up to speed from the get-go. I therefore decided to forfeit my customary group sighting laps, and instead offered to sit-in as passenger with Chris Whittle in his much modified yellow GT4 for his 20 minute group lap session. I was looking forward to comparing the experience with previous passenger laps in Chris W's GT4, following the extensive engine conversion work he had commissioned in Germany earlier in the year. Immediately upon starting the group laps the extra power and torque extracted from the 981 GT4 engine became clearly apparent. From inside the cabin, the engine sounded smoother and quieter. A fact confirmed later when Chris was lapping in the company of another yellow GT4 on the track while I observed progress from the pit lane wall. After a few laps Chris had nailed the lines pretty well and was all set to give the track a real go.
I had a queue of people lined up for some passenger laps with me. My former school pal John, drove down from Aberdeen for the occasion. As a life-long motorsport enthusiast, John had been looking forward to passenger laps around Knockhill with me in my GTS, so this was an ideal opportunity for me to oblige. I am always conscious of my responsibility as the driver on track days. I try not to unduly alarm passengers by going too fast too early. The cornering speeds and braking forces on the track bear no relation whatsoever to normal public road driving. All Porsches are fast, and their true performance potential cannot be legally or safely demonstrated on the public road. I also have a responsibility for my passengers safety. Showing-off is not an option. My purpose during passenger track laps is to steadily build the pace to a level comfortably within the capabilities of both the car and driver. In my experience over many years, no passenger has pressed the panic button or yelled "stop the car I want to get out". It's not my business to scare people.
The PCGB track day team of George and James conducted a well organised and well practiced programme of administration. It was George who approached me in the paddock announcing that he had noticed I was circulating Knockhill quite quickly in my 718 GTS, and requested to sit in with me for a few laps to experience the 718. Altogether I had a total of 6 passengers accompany me around the circuit. My benchmark lap times with a passenger are normally in the 61 to 62 second bracket. I normally do 6 to 8 lap laps at a time, including an out lap and cooling down lap. I made an exception on lap timings with my final passenger, former Knockhill sprint champion Matt Collins, but more of that later.
First a word about tyres. Regular readers will recall my comments on the Michelin PS4S tyres being sticky for only two hot laps on the track before going "off" and becoming all slidey. I can now report a further development on this tyre's track performance in my experience. When the PS4S N0 reaches the slidey stage, this condition plateaus out and remains constant and surprisingly consistent for quite a number of subsequent laps. To be clear, I'm not talking about Top Gear power slides here, my track driving style is more akin to the STIG than Chris Harris. The way my 718 GTS geometry is set up, I found the car adopting a four-wheel drifting attitude on fast curves. This could be controlled by keeping the steering wheel almost straight ahead, with the car sliding uniformally at a tangent to the radius of the corner. It was an immensely satisfying thing for this driver to achieve, made so much easier by the extraordinary composure of the GTS chassis. I discovered that I could readily complete 4 such hot laps on the PS4S without unduly overheating the tyres. The maximum tyre temperature recorded during this period was 2.7 bar. Up 0.2 Bar from the initial warmed-up stage of 2.5 Bar. Michelin Cup 2's are still the daddy. But my experience last Sunday showed that PS4S N0 tyres at Knockhill, on my car with my geo settings, can turn in a very respectable performance for a road tyre.
Returning to Matt Collins. Matt is a very accomplished Knockhill driver and also a successful racing champion. With Matt's agreement, I requested he give me some feedback on a few hot laps as passenger in my 718 GTS. As he is a seasoned motorsport competitor, I pushed the boundaries a little harder with Matt on board and posted my first ever sub-one minute time at Knockhill with a 59.2 second lap. I was delighted to say the least, especially with the extra ballast of a passenger on board. Matt's feedback proved extremely helpful. He noted that I was perhaps carrying too much speed into Turn 4 causing my car to drift too far to the left for an optimum entry into the chicane. Even so, a sub-one minute lap time was dream come true. Now for a go on my own in the car.
At track speeds the threshold of grip is considerably compromised by the extra weight of a passenger. Having such a well developed and balanced chassis the 718 GTS handling is notably different at track speeds with only the driver on board. Cornering, braking, and acceleration dynamics are all improved without a passenger. I had already decided this was probably going to be my final track day as a driver. Now was the time for me to give it a real go. All the planets were in alignment, I felt good, the track was dry, I had a light car with low fuel, the traffic on the track was light, and the sun was shining. I had already experimented with gearing at Turn 3 and proved second gear as being faster, with a short shift on the paddles to 3rd before the right hand kink, Butcher's, leading up to the chicane. I had also tried full auto mode with a manual override a selected points, but for my ageing brain this was too much to think about at critical places. So manual shifting was best for me.
With a clear track in front and behind, I reawakened my competitive motorsport spirit and absolutely went for it in qualifying lap style. The subsequent result exceed my wildest expectations with a best lap of 58.7 seconds and a top speed under the Beatson's bridge of 123 mph. I had smashed the one minute barrier at Knockhill by a considerable margin. This time and speed was recorded by GPS on the Porsche Track Precision app. No dodgy self timing on the PCM. I also have the data on my iPhone to analyse and look back on. Unfortunately, in my mental preparation for this special lap, I forgot to activate my GoPro camera. No matter, I couldn't have wished for a more fitting end to my motorsport and track driving experience. I was over the moon! To post such an incredible time on road tyres, in a mainstream Cayman at 72 years of age, was way beyond previous comprehension. The high will now be with me for more than a week.
Some photos to follow from my fabulous final day at Knockhill as a driver for your interest.
Brian
]
