*The radiator manufacturer will have a maximum number based on how
    stiff the flat sided tubes are. Too much pressure rounds those
    tubes and then pulls them loose from the fins when pressure is
    removed. Also the rounded tubes slow airflow through the radiator. *
    *Racing radiators tend to have higher pressure ratings than auto
    radiators. *
    *Most racers run 16 to 22 pound caps. Higher pressure means higher
    boiling temp for the coolant.  Also more stress on the
    connections. With a 2" hose and 22 pounds you have just about 70
    pounds trying to pull the hose off of the fitting. With silicone
    hose and safety wired clamps it would not be a factor. That does
    not include Chinese replica clamps. Just real American made name
    brand clamps. You can also use real aircraft quality clamps
    already drilled for safety wire. *
    *Many modern cars use no pressure cap. Just a sealing filler cap
    on a make up bottle.*
    *An air space above the coolant level provides a volume of air to
    compress to control the pressure. If the moron at the gas station
    fills that bottle all the way up while reading the message on the
    bottle not to fill above this line,*
    *the end tank will blow off of the radiator just like on my wife's
    car. *
    **
    *The 22 pound cap is middle ground, a bit more insurance, not
    likely to hurt the radiator. *
    **
    *I use 22 pounds. Distilled water with 10% glycol and either
    Redline Water Wetter or 1/2 teaspoon full of dish washing
    detergent. It is gentle on the hands. Never a problem since 1980.*
    *Lynn E. Hanover*


Hey Lynn and the rest of you smart guys, What is your opinion on scheduled hose replacement?  My plane has been flying for 6 years now and I just finished the annual.  I decided that 6 years was long enough on some of my radiator hose and decided to replace it.  In particular, I ordered up the AN-16 steel braided hose (Earls Perform-o-flex)  for my coolant out line but I just couldn't bear the thought of cutting and fitting that stuff and hoping I don't get leaks or damage the AN hose fittings or cut my fingers to shreds.  So I decided the current hoses were good for another year.  Maybe a justification...

Opinions on scheduled replacement of SS hose?

-- David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net