lessened due to a reduction in the vap prs....
At 212F,
water vap prs. = 14.7psig,
50:50=12.2psig
so 50:50 gives you about 3.5psi extra headroom (in your favour) at 212F.

At 130F (55C) (Wood's test temp) vap prs. water = 2.5psi - so much lower.

The 6lb radiator cap gives you another 6psi headroom = 9.5psi head room over plain water.


I remain a little sceptical about this cavitation issue - only because the pump is not a serious pump
ie: the CM90 is a "small" moderate speed pump with about 4psi output in application. Similar to your fountain pump.
In situ (in the car) - it is seeing a 0.8psi flooded suction.
I'm checking the Net Positive Suction Head Requirements (NPSHr) with lhmarine who are talking to Sweeden.

But have to respect Waldig's experience, "nous" and "optical integrator".

Anyone know the rpm of the CM90?