28 January 2023 - 'Passion for Speed' at Zwartkops Raceway
The car was tested for the first time since the extra anti-roll bar was fitted a week before the race. The handling was completely different and the new set-up stopped the skittishness and squirming under braking. It now braked comfortably in a straight line and also felt far more settled through the corners. The car was still relatively slow and the best I could achieve was a 1:24 around the track before the car started to misfire as if it had run out of fuel. By the time we got home to unload the car, it would not start at all and the fault was traced to the seals of the fuel filter, which had become soft and split. A new filter was sourced and replaced in time for the weekend's race. Tyre pressures were still a bit of a mystery and my friend Alan suggested that we increase the tyre pressures at the front from 2.2 Bar to 2.5 Bar and keep the rears at 2.2 Bar.
Qualifying took place on Friday afternoon and the car felt much better with the harder front tyres and I managed to take 3 seconds off the time from Sunday, qualifying 7th on the grid at 1:21.7. We decided to further increase the front tyre pressures to 2.7 Bar for the race.
​
For the first heat, the grid was revised and I found myself 5th on the grid behind two Minis, two Darts and a Lotus Elan next to me. I lost a place to the Elan in the first corner, but during the next two or three laps the Lotus made it's way up into third place with the Mercedes close behind. I was then able to pass the Lotus and by the second last lap was battling Kyle Brink in his Mini for second place with the Lotus Elan biting at my heels. It was very close and exciting racing.
I got into a rhythm late in the race and was very impressed with the performance of the big Mercedes, considering that it weighs 1550kg versus the 650kg of a Mini. I was able to brake as late as the lighter cars and and sometimes out-braked them - much to my surprise. I also found the big car could keep pace with the lighter cars through the corners - again to my surprise. The biggest surprise was to get down to a fastest lap of 1:19.5 - that was almost two seconds faster than in qualifying!
​
Heat 2 was not as successful. My fastest lap of 1:19.5 was below the minimum time restriction of 1:20, so I was bumped down the grid into 5th place again. I lost a place again in the first corner, but by the end of the first lap the two GSM Darts had taken each other out and I was up to 4th place. The safety car came out at the end of lap 2 and the next few laps were a procession. Racing resumed on lap 5, but the Mercedes started to lose power through the corners with fuel starvation which got progressively worse. I ended up in 5th in heat 2, but 4th overall and 4th in class.
The fuel starvation problem was traced to be the same issue as in the previous week's practice and it seams that the 102 octane racing fuel was reacting with the seals in the fuel filter, softening them and allowing them to split.
​
The video clip below is made up of all the clips sent to me by friends and some exciting in-car footage that shows how close the racing was.