Randall, Thanks for the feedback on the fans & water wetter. I went with 1 bottle of Water Wetter, 1 gallon antifreeze and then topped off with water to get ~30/70.
To see if my mods were effective, my race profile had me getting up into the 160s at mile 4 thru 10.
I maxed out at 239 coolant & 169 engine oil
When I slowed down to high 140s the temps dropped to 232 & 168
The cooling improvements had modest, but noticeable positive impact.
The needle on gauge was always close to top line, and just barely over.
In May, needle was almost out of range and service light was on.
Decision now was whether to stay with the Race Profile that had me trying for checkpoint challenge or back off and only go for Finish.
The temps seemed reasonable enough, but I decided to ditch the checkpoint profile, because the car did not seem responsive enough.
Plan B was to average ~152 up to the narrows and then be in the low 150s post narrows which worked out well.
Temps popped up Coolant-240.8 and Oil-172 and 300.2-rear diff when I had throttle at 80-90%, I assume going uphill at ~23 minutes into race
After that, temps went down to 217 and then ranged for Coolant: 217 to 237, Oil: 168 to 173, rear diff: 280s-300 and maxed out at 304 at end/finish where I had 100% throttle again briefly.
Intake air ranged from 70-77 and didn’t seem to have a relationship to speed.
I measured the air flow with an air speed indicator and an absolute pressure sensor and the data didn’t point to any noticeable back pressure.
I monitored the Coolant fan activity by measuring voltage at positive side of fan 2.
If the voltage is half of battery voltage, then the fans are in low speed mode.
If the voltage is full battery voltage, then the fans are in high speed mode.
The fans started out in low speed and when I reached 120 MPH and coolant temp of 205, they kicked in to high speed and stayed that way until ~2 minutes past the finish when the coolant temp was 199.
They went off ~3 and a half minutes after finish when coolant temp was 195
I've attached the HPTuner Coolant Fan params.
The shop that does most of the work on my car had made some tuning adjustments based on some mods and they provided me with a snapshot of the Coolant Fan params.
Dave, the tuning mods look similar to yours so I don't know why the fans are still on.
Sluggishness:
There was a head wind and I heard others also complained of some performance issues.
I am also wondering if I might have limited air to engine by my trying to force more air to radiator.
I might change some of the ducting to see if more air will flow up to air intake.
I will also try to block off any air from escaping the air intake & radiator area.
End result was car ran cooler and I made it to finish OK so I was happy.
Andy