"Engine" Temperature Measurement.

[Dusk Blue Z]

Sam,

I use these in my line of work (Predictive Maintenance) I’ll try and explain the short version of how they work and how you can get different readings from them. All the Infrared units work off a diverging cone starting from the sending unit, the farther you are from the source the bigger the area you will be measuring. You could get the specs on your tool but a circle of 12” over a distance of 10’ would not be unreasonable. The laser pointer will just show the center of the circle. Try and change your distance to the target and see if the temperatures don’t change as well.

Any temperature measurements that you get from the surface of an object are radiated readings. Different colors radiate heat differently; there is a reason that radiator’s and race motors are painted black. Materials will also have an effect on the radiation of heat.

Thinking of the temperature differences of your sensor, your lower reading is reading the casting and sensor, the middle reading will be mostly sensor and the top reading could be the black Bakelite material and the background surface.

If you were to use Thermography to capture a thermal image of your engine you would need to have some point of reference to determine what the actual temperatures of the different colors and materials would be. In industrial electrical applications we use a piece of black electrical tape as our reference point.

There are a lot of areas where Thermography could help to solve some problems in automotive applications. I have heard that some NASCAR teams have used it to look at their tires surface temperature during test sessions.

Not so short an answer, but hope it helps.

Mike