low pressure or high pressure radiator cap??

[FlyinGN]

I have a low pressure cap on my rad now and just got a beCool alum to replace it. My question is..
* does a rad cool better (or worse) when you have a low pressure cap on vs a higher pressure cap?

Im talking a 7 lb vs a 15 lb

 

[buickboy]

Frank-
Stock pressure is suppost to be 15-16 lbs. Don't go over that as it will blow out the heater core and other components in the system. Been there, done that.
Mitch

 

[FlyinGN]

I know Mitch. Im talking about the stocl 15 lb vs 7-8 lb low pressure..

 

[Nick Micale]

There should not be any difference in cooling from a stock 16 psi cap to using a 7 psi cap. However, at 15 psi water will boil at 250 degrees and much less at 7 psi. The low pressure cap may also allow coolant to escape after shut down as the heat released from the engine will raise the radiator temps/pressure.

We cannot do that with our temps here, and even a worn 16 psi cap will leak, sometimes when driving.

 

[FlyinGN]

Thanks Nick, thats what I was looking for..

 

[chevyII]

ratio

3 degrees for every pound most components wont give till 20-22 lbs. if you can find an 18 it would cool 33 degrees less than 7

 

[FlyinGN]

are you saying that a 7 lb cap will cool 33 degrees *BETTER* then an 18 lb cap?

 

[chevyII]

the other way around 18lbs=33 to a 7lbs. that is not cooler but raising the boiling point=water boils at 212,18lbs=52dgrees+212=264 that your water will begin to boil plus antifreeze mix will raise that alittle more. your car runs the same temp but it makes it about impossible to boil the mix