I had a customer ask this question today and figured I'd write it down and print it off for him
In the USA we usually see radiator caps sold with LB measurements on them.
Then we see a radiator cap with 1.1 and we think... 1.1 lb?
That's not very much?????
But in reality that is 1.1 Bar, not pounds.
1.1 Bar is equal to 15.95 pounds per square inch.
Below is a chart that shows various Bar to Pound conversions at sea level:
1.0 bar = 14.5 pounds per square inch
1.1 bar = 15.9 pounds per square inch
1.2 bar = 17.4 pounds per square inch
1.3 bar = 18.9 pounds per square inch
1.4 bar = 20.3 pounds per square inch
1.5 bar = 21.8 pounds per square inch
1.6 bar = 23.2 pounds per square inch
1.7 bar = 24.7 pounds per square inch
1.8 bar = 26.1 pounds per square inch
1.9 bar = 27.6 pounds per square inch
2.0 bar = 29.0 pounds per square inch
If you are at Sea level the boiling point of pure water is 212F
If you are a mile up at 5,280 feet, water will boil at 203F
So, keeping a cooling system under pressure helps raise the boiling point.
For every 1 pound of pressure the cooling system is under should allow you to about 3 degrees F more operating temperature.
Taking the above chart and adding the boiling points nets us the following:
1.0 bar = 14.5 pounds per square inch = a boiling point of 255 degrees F
1.1 bar = 15.9 pounds per square inch = a boiling point of 259 degrees F
1.2 bar = 17.4 pounds per square inch = a boiling point of 264 degrees F
1.3 bar = 18.9 pounds per square inch = a boiling point of 268 degrees F
1.4 bar = 20.3 pounds per square inch = a boiling point of 273 degrees F
1.5 bar = 21.8 pounds per square inch = a boiling point of 277 degrees F
1.6 bar = 23.2 pounds per square inch = a boiling point of 282 degrees F
1.7 bar = 24.7 pounds per square inch = a boiling point of 286 degrees F
1.8 bar = 26.1 pounds per square inch = a boiling point of 290 degrees F
1.9 bar = 27.6 pounds per square inch = a boiling point of 295 degrees F
2.0 bar = 29.0 pounds per square inch = a boiling point of 299 degrees F
These figures are for reference only...
If your running temps are close to the boiling point better do something about that FAST!
Note:
Do I recommend a 2.0 cap on my kx500?
Nope, I just ordered the 1.6 cap that is a factory option for the kx500.
P/N 49085-1073
Boiling point of 282 degrees F is more then enough for my usage
