radiator cap

hi,

i have 914 HOMEBUILT Aircraft.

on 50/50 DEX COOLANT, i have run the Engine i.e SUFFIX01, the COOLANT become boiled at 115C. IT filled the expansion bottle at 115% THROTTLE. i was worried.

should i go for FLYING? whereas ambient TEMPERATURE was 39C during Ground run.

what to do?

If you boiled at 115°C, your radiator cap vented at 0.7 Bar instead of 1.2 Bar. 

1.2 Bar does not boil until 124°C.

If you boiled at 115°C, your radiator cap vented at 0.7 Bar instead of 1.2 Bar. 

1.2 Bar does not boil until 124°C.

what you suggest for keep me out of boiled? either changed pressure cap? or else.   or any other suggestion?