I was just ordering some stuff from mazdatrix, and I noticed that they sold a pressure cap from Greddy. I believe that the pressure rating of the cap was 19lbs. What would be the advantage of raising the pressure of your cooling system?? I realize that it would change the boiling point of the coolant, but what would be the point of this. Id think that this would just put an unnecessary pressure on the system, but if there is a major advantage of doing this Id like to know. Anyone have any insight, or actually have this cap?

 

IMO, these are only a band-aid for a cooling system that’s right on the limit of boiling with a 13psi cap. It would raise the boiling point of the water from 253ºF to 266ºF (ouch!), and put more stress on your 15yo cooling hoses. There’s certainly no performance advantage from it.
Don’t be fooled by the expensive Japanese brand name. Just because it has GReddy/Trust/HKS/whatever written on it, doesn’t mean it’s guaranteed performance.

 

if i were to get one it would be for underhood dress up, not for performance.

 

I like the idea of a higher-pressure rad cap. When a rotary gets hot, localized boiling does a lot of damage - it can help act as a safeguard against that. IMO you shouldn't still be running the stock rad hoses anyway, so that's a moot point. The idea (again, IMO) is that it's a little extra bit of assurance that you can add to a well-cooled engine.

Brandon