One more update, and what I learned about selecting an oil.
I had not raced the CRX since 2010, but this year I decided to make it to the Colorado race. In the past several years I continued to work on and test the car. Since the engine at least partly had a cooling issue I worked on that. I added: an oil cooler, air baffling to the radiator inside the nose, worked out how the car wanted to have its bypass coolant routed, and settled on a thermostat. I also made sure there were no vacuum leaks. All together, those efforts paid off. Temps never went over 200F after that.
Within the rules I did what I could to the suspension. Junkyard rear springs from a heavier car, stock rear shocks from another brand of Japanese car. I'm being vague here, because, well, I consider the specifics of these things secret. They took time and money to figure out. The front struts were wiped out and leaking so I just bought new OEM Monroe ones. No secrets on the front suspension except homemade upper strut mounts to get more negative camber. New parts are pretty cheap for this car, and performance parts for it are pretty scarce that fits well with the rule set.
While not specifically performance changes, I made arrangements for a second seat and harnesses to train drivers, and I put the battery, (previously in the passenger's place,) under the car ahead of the rear axle.
Oh, and I experimented with oils. Both the type and volume of oils. I knew I needed something thicker since the OP would drop a lot after the engine was fully up to temp. I'd been using some variation of 40 weight oil, either xW-40 or straight 40. Hot pressures would decay quite a bit to 40-50psi, so something heavier seemed a clear direction to go in. Straight 50 worked great when hot, but startup pressures were pretty high and likely getting bypassed at the pump and filter when cold even if not, 80+psi cold was making me uncomfy. 20W-50 seemed to keep oil pressures at both ends pretty steady. 70psi cold, 60psi hot. That'll work.
I needed to address one other thing with the oil. In sustained turns, like turn 5 at my local track, oil pressure would drop to 20psi under throttle. I didn't know if that was entirely due to oil slosh or oil slosh AND slow drain back from the top end. For a number of reasons, I suspected both. I added another quart to the crankcase and the problem seemed to go away. But, knowing that this might create a windage problem, I used 20W-50 racing oil with anti-foaming properties to head off any problems there. During the race, the pressures were pretty steady. They would only occasionally drop below 60.
The motor is still together and it seems unhurt by the abuse it endured. We lost our tachometer early in the first day, as well as our temperature gauge, AFR meter, and volt gauge. The only gauge we had was our oil pressure gauge. We were forced to let our oil pressure gauge fill in for our temperature gauge. Since high temps open up clearances and make the oil pressure drop, we kept a close eye on the oil pressure. It couldn't fill in for the tach, and I know the engine was routinely over revved for the entire race. I was likely the biggest offender there. But it still idles pretty smoothly at 600 rpm. I was only able to make one jet change before the AFR meter left the building, so I have no idea if we were spot on or a little rich. Rich is my bet. It ran pretty well though. Fuel slosh is a problem with these carbs and it's just something we have to live with.
Just thought some of the posters to this thread might be interested in an update.