my $.02.
In my earlier days of tracking the NSX I too experienced oil related pressure problems. As I pushed the engine harder and harder for longer periods of time the oil pressure dropped as oil temps came up and the RPMs remained high. The oil pressure problem was solved after realizing the oil that I was running appears to have been foaming at high RPMs. A fellow racer and I changed the oil at the track to straight 50w (not my first choice, but perfect for this test) racing oil and this problem was solved.
As I pushed the car harder yet the stock cooling system, with water wetter and water only, could not keep up...water temps went into the red. I may have gotten lucky with my track car's cooling system so I thought I would share the set up. I ran Willow Springs last week and the car is running 7-8k rpm constantly and I am seeing water temps of 180F - 200F. California Speedway and Button Willow in the summer had the same temps.
Ron Davis Radiator (with a stone shield in front of it)
Water with Water Wetter (no Anti-Freeze)
2 FAL Cooling fans
Heater removed, (heater hose by-pass has bleeder in it)
O.E. Thermostat (fully assembled and functioning)
Cooling fans triggered by Thermoswitch and also by a cockpit mounted Thermoswitch By-Pass switch.
In this car the cooling fan By-Pass switch really makes a difference on overall water temp. If I allow the thermoswitch to activate the fans on the track the temps will go to 220+ F, but if I turn on the fan By-Pass switch as I roll onto the track, so the fans are running 100% of the time, I never see water temps climb beyond 200F, even in July. It appears that once the cooling system saturates with heat the upward cycle of heating begins and will not stop until you reduce the RPMs. By never allowing the temps to reach the capacity of the cooling system it seems to be able to maintain a reasonable temperature. I can't fully explain why my fan by-pass switch works so well to keep my temps down on the track, but I don't really care, it's clear that ram air is not enough and that with the aid of the fans running 100% of the time the cooling system is adequate. Slow speed corners at high RPMs and close proximity to other vehicles obviously reduces the ram air affect drastically and the slow response time of the thermoswitch may explain why a by-pass switch works so well.
Three other notes that are benefiting the cooling system and should be considered:
1- This car is running a 12 qt engine oil capacity with a large oil cooler. Oil temps are usually 215-218 F under hard track use.
2- This car is running a 4 qt transmission capacity with a moderately sized oil cooler.
3- This car is 500 pounds lighter then stock.
I don't know if this info. helps at all, but at least it will give you a bench mark for a track car that is cooling correctly.
Good Luck,
Chris
