Boost is heat = reduction in power at point X.
My experience is that naturally aspirated power is more reliable power on a road course. Heat soak is evil to boosted cars. There have been many methods tried to reduce it. Heak soak becomes a probem when the intercooler can no longer shed off the extra heat produced by the blower/turbo.
That said I have also seen boosted cars without over heating issues in the cooling systems. So It think we have two issues here. They collide at some point and feed off one another to make the entire situation worse.
For blown and turbo cars some of the soultions are:
Add an intercooler - Done
Add a bigger intercooler - Done
Add a water based intercooler - Done
Spray the intercooler with a mist of water to remove heat soak - EVO has one
Run water or methanol injection to cool the intake air - Lots of opinions here.
Add yet a bigger intercooler-
More air flow to the intercooler -
Water Wetter will help, but it is not real likely it would have totally solved your issues in a short tight track in very high temps.
We have two issues to attack. Improved cooling system performance can help the heak soak issues as well. But there are plenty of cars that do not overheat the cooling systems and still have heat soak that reduces power.
If you were to go to the EVO, Subie, BMW 335i forums you will likely see the same discussions on heat soak and some on engine cooling. If you go to the Corvette forums they will talk about oil temps getting too high on the C5 cars.
Personally I hate short tight tracks as they are hard on any car. Not much chance to ingest good air. Drafting other cars also tends to reduce the performance of the cooling system as well. Some call it getting dirty air. On short track you have to learn to rely on momentum vs. brute power.Your instructor is right, but I think 3,000 - 4,000 is pretty low. Maybe a 5,500 redline is what I would try for those kind of tracks in hot weather.