We made two jetting changes during the morning, after a session of running. AFRs we originally in the 11:1 range, which is a bit rich, which we knew it would be. We bumped down from 165 mains to 160 and down to 155. AFRs were very solid in the 12.5 range after the last change, in the 90-95 degree heat. A funny thing happened too, as we leaned the car a bit. I picked up about 500rpm on the front straight! I'm now just touching 6,000rpm in 4th on the front straight.
The new cooling scoops seemed to do their job too. Oil temps would get up to about 220-230 degrees after a few laps, but just stablized there. The previous event with the new motor and cooling fan, temps would get to 250 pretty quickly and I couldn't run full throttle down the straights the last few laps of the sprint race. This time, I had no issues. and it was at least 10-15 degrees hotter outside temps.
I also had a Cylinder Head Temp gauge and sending unit installed for the first time. I didn't know what my head temps were before, so it is always a case of "new information can be too much information." Head temps generally ran in the 400 range, and never got much hotter after many laps in the heat. I have a temperature compensated Mini 1000 CHT unit from Aircraft spruce.
I did have two "funny" problems that caused me to have to get towed in. On the second track session, the car just shut off on the exit of turn 5. I was able to coast around and park it in a safe zone in a bypass road. Turns out the coil wasn't as tight as it should be in its mount, so it fell down and pulled the main hot 12v wire connection off. We fixed that, and got it nice and tight. The second problem happened on my last session. Again, the car just shut off on the main straight. I figured it was the same problem again, but it wasn't. In the pits, the car wanted to start, then wouldn't, then would, etc. It ended up being my last session so we just packed it up. We found a loose wire connection on the main power switch back in the garage. Over the winter I'm going to rewire the car anyways, as I've added a bunch of stuff lately and don't like the mess of wires behind the dash.
So I ended up not running the race sessions, but actually ran more in the day than I usualy do. I did a bunch of shorter sessions and am pretty pleased with the performance of the car, and the tuning we got done. I was 10 seconds quicker than the last time we ran the cyclone configuration on the dunlops vintage tires. Not bad!
It was also fun having Sean down for the event. He brought his Subie 2,5RS and ran his first track day at Thunderhill. I had a blast playing navigator for his first couple sessions. Makes me miss my Subie!
Coming in after a session:
Sean's tow and race rig:
Getting towed in:
Chris H.
