Author Topic: Infered temp tester  (Read 4692 times)

barry100

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Infered temp tester
« on: June 19, 2009, 01:20:45 AM »
Hi All
I'm thinking of gettig a infered temp tester, I want to use  on multi cylinder engines ie HR 3, at the moment I put my finger on the corner of the cylinder heads  which is OK for about 30 seconds, I need to know if they are balanced in regard to heat/fuel supplied,The model I have in mind is a one that goes up 300 C, would that be suitable? and would check the same place the corner of head which is an  aluminium alloy.

Stan

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Re: Infered temp tester
« Reply #1 on: June 19, 2009, 02:03:33 AM »
I'm sure it would be fine.  If you are interested in the most accurate measuring method, get a can of flat black spray paint (the smallest, cheapest you can find) and determine where you want to check the temp on your engine.  Spray a small round section with the flat black everywhere you might want to check. 

That will give you the most accurate reading you can get.  Light colours, shiny surfaces both degrade the accuracy of the IR temp gauges.
Stan

adhall

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Re: Infered temp tester
« Reply #2 on: June 20, 2009, 02:45:24 AM »
The emissivity is only one of the factors involved.

The temperature indication is also affected by the the angle between the line of sight and the target. You will see a maximum reading when the device is pointed straight on at the target. The indication will drop off if you angle off in any direction.

Another factor is the size of the field of view with respect to the target. As you move farther back, the field of view will increase. If the field of view grows to include objects that are at different temperatures than your target, then the temperature indication will go up or down according to the weighted average temperature of everything the device can "see".

In other words, to get consistent results, you should shoot straight on at your target from the same distance each time. For small targets, get as close in as the device will allow (look at the spec sheet to find what the minimum sensing distance is).

By the way, some of these IR temperature guns have a laser pointer built in which helps considerably with hitting your target consistently.

Best regards,
Andy Hall
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Bluecometk

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Re: Infered temp tester
« Reply #4 on: June 20, 2009, 03:27:29 PM »
I have been using laser pyrometers for years on our team race engines. The units we have are very accurate at the high temps we use them. We also have pyrometers in the exhaust ports in each cylinder to compare the two temps. The average variation between the two test types is about 7 degrees F. This could be because they are reading two different types of temp, surface temp and gaseous temp. The only other difference is a slight delay in the timing from the two when they actually read the temp. They have saved us many times. The units we use are fairly high dollar units. We have some lower priced models that work quite well, they are a little slower and 1 or 2 degrease less accurate. They all are well worth the Expense.

Just my two cents
Bluecometk

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rcavictim

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Re: Infered temp tester
« Reply #5 on: June 22, 2009, 05:55:35 AM »
I have a laser thermomenter and use it a lot on my small disel engines.  Coudn't be without it!  Painting a flat black measuing spot of the various temperature monitoring spots is very good advice.
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barry100

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Re: Infered temp tester
« Reply #6 on: June 23, 2009, 01:19:38 AM »
Hi all
I have bought a Raytech ST20 PRO c/w a laser indicator, next question, what would be a reasonable temperature differance between the cylinders to aim for say 5- 10 oC ?
Barry

Bluecometk

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Re: Infered temp tester
« Reply #7 on: June 23, 2009, 02:10:23 AM »
If everybody is doing their job correctly I think the cyls should only see a 20-25 F difference between them under load. When you are checking big bore V12 and V16 turbo charged engines.50F to 75F is acceptable under high boost and that is sometimes dependant on cylinder position in the cooling system.

Just my two cents

Bluecometk
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nobby

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Re: Infered temp tester
« Reply #8 on: June 23, 2009, 12:42:18 PM »
Granted its a HR so no coolant, however still exhaust temp should be used for balancing cylinders, taken as close to the head as possible.  For coolant engines accuracy is based upon the balance of the coolant flow etc and only really tells you somewhat as to how hard the cylinder in question is working.

Cheers
Nobby
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