<VV> re:CHT readings

[Frank F Parker]

On Sun, 24 Oct 2004, tom zimmermann wrote:

>           I have a Raytek Rayriger ST2 i want to use to check actual head temp.As i don't have any instructions with it,i'm not sure yet how accurate it is,or how or if air temp affects the reading of surface temp. I tried using it last winter to spot attic heat loss after one window filled up with ice.Anybody else use one of these? Tom
>
>
You need to be carefull using an IR meter for measuring temps of alum or
similar shiny surfaces. They are designed for a "black body" surface or an
emision of about 0.9- eg typically a black surface. Some meters have a
knob to adjust for measuring the temps of surfaces of different emmision.

I had my meter at last weekends C5R race at Laguna and was measuring the
temps of the radiator, oil cooler, thermostat housing ( yes, we use one to
avoid having to tape radiator openings). When I measured the temp of the
dark blue hose and the alum tubing connected to the hose, the alum tubing
measured 60 deg cooler than the hose even tho they are about the same
temp. The meter was fooled by the shiny surface of the aluminum tubing.
Spraying a little flat black paint would solve that problem but I suspect
you do not wish to do that with your heads, tho you could mask a small
area, run your tests, and scrape it off.

regards,

frank