Exhaust Manifold Surface Temperature Part 2

Today I made some more readings of the surface temperature of the driver side exhaust manifold from engine start through ten minutes total time.

I’m using a Craftsman IR temperature sensor to record the surface temperature of the exhaust manifold.  This time the exhaust manifolds on the car have a black thermal barrier coating on them, as shown in the picture below.

Ported & Polished Exhaust Manifold on Flowbench
Ported & Polished Exhaust Manifold on Flowbench

The ambient air temperature was about 20 degrees cooler today than when I made the previous recordings.

I have also noticed that where the IR sensor is pointed can affect the reading a good amount.  To try and minimize the affect on the results I picked a marking on the surface of the exhaust manifold to point the temperature sensors laser pointer at each time.

Below are the results from the previous testing with the latest results added on.

Exhaust Manifold surface temperature chart reading with IR temperature sensor

I am a bit surprised by how much less the temperatures recorded on the coated exhaust manifolds were.  The only apparent differences aside from the coating was the ambient temperature, but I would not expect it to have such a strong influence on the exhaust manifold surface temperature.  Ideally I would be able to log under the same ambient temperature conditions, but given the time of year that it is now it is unlikely that temperature conditions will be equivalent in the near future.

The other question I have is to how well these results would carry over to a longer period of time, when the car has been operating with a load on the engine.  This experiment only spanned ten minutes and was done entirely with the engine idling.