What do you think of this plot

It’s my coolant logged from Torque pro on my evening drive home. Looks like my coolant flush and new parts didn’t help solve the problem. From the looks of it I see 2 possible reasons the chart looks like this:

1. air buble

2. Insufficient radiator capacity

The curve shows me that the T-stat is opening properly, and the high idle cooldown suggests that its not a lack of water flow. To me I see it like this:

Engine warms up internally at the right rate, heating curve slows and levels at the right rate with a thermostat opening, once a certain level of heat is reached the radiator simply can’t reject it fast enough and it snowballs.

It will run perfectly on this curve every time, It could be 110 out and it would heat up to 186, sit level there or maybe go to 190 for about 10 minutes, then climb. This was on a 95 degree day at 5000 feet on mostly level roads with light load.

I reached out to the radiator manufacture (CSF) to see if they will warranty their unit but I have low hopes for that. coolant is fresh 50/50, hoses are good, clutch fan kicking on properly and heats up at high speeds (with load) where the high airflow should solve any fan issues anyway...I mean at 80 mph the fan should only be a small part of the airflow equation. Any thoughts?