Im looking for advice on the pressure for my racecar engine cooling system. Currently on my 1990 3sgte Im using a stock 0.9bar coolant neck cap and today after shutdown my coolant temp went up to 105 Celsius and started overflowing. There was a lot of gurgling in the system.
 
I got a tridon 1.1 bar but the fit was terrible and I didn’t want to risk it. I have a TRD one which fits perfectly but its 1.5 bar and Im worried I will start popping hoses if I use one.
 
What are the others with racecars using?

105 C should not cause overflowing if the system is pressurized at 0.9Bar.  Be suspicious of that original pressure cap.    Test with a Mityvac. or similar .   1.5Bar should not cause problems with hoses but it is getting up there with radiator tanks ,water pumps and that poxy O ring on top of the coolant outlet.    More gentle cool down laps maybe.

Thanks for the reply Doug.
 
The stock radiator fan control is an issue so I bought an aftermarket controller and will fit it over the next few days. That combined with a proper cool down will help no doubt. The run today was just a blast down the freeway so nothing as intense as a hot lap.
 
To get the 1.1 bar cap to fit I would have to shave off 0.5mm off the 'wings' on each side of the cap and Im not comfortable in doing that. The lowest TRD one is a 1.3 bar so I might wander down to see what Toyota has.

I would be suspicious of a blown head gasket. Gurgling etc is a sure sign of it and thats what my original original 3sge ended up having.