25PSI radiator cap, any reason why not?
 

an I run a 25PSI cap? I am concearned about the O Rings, or anything else that may not have occurred to me. Thanks, Carl

copy / paste from Mazdamotorsports.com:

Pressure
Increasing the cooling system pressure by changing the cap will raise the boiling point of the fluid and will also keep the fluid from being expelled into the overflow tank. We recommend use of a radiator cap with a pressure rating no higher than 17-18 lbs.

Carl,

Have you considered the Evans coolant? Pineapple Racing swears by the stuff. A friend of mine that races an American Sedan Mustang cured his overheating with the stuff.

Water wetter works well too.
I assume that you have made some kind of ducting for the radiator?, because that nice huge IC seems to take all the air.

I can run at 450-480rwhp for 20 minute boosting about 60 % of the time, Occasionally(once) I overwhelm the 16lb cap, and all my coolant is expelled in about two minutes. I have replaced it with a 21-25lb cap for now, and sealed the system. about 1/3 of the frontal air is directed around the IC and into the radiator, and oil coolers. Carl

What temp was the coolant at when this happened?

I use a STANT high pressure cap on my HOWE aluminum radiator. 9600rpm 12a J-Bridge I think it's 25-29psi. NO coolant overheating probs. On cold days it'll run 140*F and I have to put duct tape in front of the radiator. On a typical summer @ Buttonwillow, it'll do 200-220*F.

I use 22lb cap on the ITS car. Never had a problem. If a couple hundred psi of combustion pressure isn't blowing the seal out I doubt the pressurized coolant will blow it in. Hell, with the amount of boost I'd guess you're running you're probably break even in the intake area. :D