[DeTomaso] Infrared Thermometers

[JDeRyke at aol.com]

In a message dated 10/19/07 4:15:03 PM, artstephens at charter.net writes:

> I just bought an IR thermometer from Sears that measures up to 1000 degrees 
> F.  I am wondering if I should get one that measures higher temps? If 
> exhaust gas temps are too high, could that be measured by pointing this thing at 
> the headers   I have seen my headers glow red at night while spinning the 
> engine up to 5 or 6,000 rpm. It seems that maybe these could be used on a dyno as 
> well? 
> 
Maybe if the gauge is an expensive one. I bought one like yours a few years 
ago with a 0-1000F range and tried it at idle a few inches out from the header 
flange (pipe temp drops off incredibly fast with distance from the heads). It 
turns out that these gauges have a projected spot size that influences the 
temp read, and the influence grows as the temp increases or the distance from the 
heat source increases. Even using the built-in laser aim and getting close 
enough to be uncomfortable,   I was unable to hit the same temp twice on my 
headers. A variation of only a few thousandths of an inch in the spot selected 
gave over 100 degrees F difference. It works fine at lower temps like checking 
radiators or my tortoise's night time temp without disturbing him, but the 
variation is just too much at 800 degrees with cheap gauges IMHO. Try it with yours 
about 6" out and see what I'm talking about. Good luck- J DeRyke



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