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-   -   How to use my temp guage correctly. (https://www.rctech.net/forum/nitro-road/79521-how-use-my-temp-guage-correctly.html)

silacomalley 07-31-2005 05:28 AM

How to use my temp guage correctly.
When I use my infra red temperature reader, do I point it at the heat sink or down inside the heat sink toward the glow plug?

Temp against the heatsink is 179 f & the temp against the glow plug is 210 f.

gonzoY5 07-31-2005 07:37 AM

POint it at the plug. you're looking for the hottest temp

goosein LV 07-31-2005 08:55 AM

goose is quackin
make sure to have an accurate thermometer trust me :nod:

Dishy 07-31-2005 06:15 PM

I have a couple of quick questions,

1. Is it an infra red thermometer designed to be used with RC engines?

2. Have you check it againist any other thermometers? You can always compare it to other thermometers at the track or maybe your friends have one.

3. Why don't you use a thermocouple? It is probably more repeatable, you can record highest temperatures reached and it is cheeper.


silacomalley 08-01-2005 01:25 AM

Well it is an infra red designed specifically for r/c nitro temp reading. I checked the review of the product before purchasing & found that it got thumbs up all round from various sources. I haven't checked it against anything else, though thats a good idea.

It has a couple of features, it lets me take multiple temperatures and monitors the temp over time to give me an average. It stores temperature readings etc.

Whats a thermocouple?

Tommy Bergfeldt 08-01-2005 01:57 AM

One thing that's very important is that you should'nt just point and shoot at some distance to the plug, you should press the temp gauge as close to the plug you can get, then you will get more exact measurements

silacomalley 08-01-2005 02:41 AM

Yes, I try to push it down on the top of the cylinder head & point it toward the glow plug. I think it's fairly accurate.

This is the temp guage I'm using http://www.tempgun.com/order.html#pe1

It's the PE-1

Dishy 08-01-2005 06:01 PM

Just had a look at the PE-1 at the link you posted and I have noticed a few things to be careful of.

The emissivity appears to be set at a fixed value of 0.95. This is a bad thing because the emisivity of a nice shiny piece of metal is usually closer to about 0.50 or less. I know this probably sounds a bit confusing and makes no sense but, what this means is that depending on the way the instrument is designed you could be getting errors of up to 20 Degrees celcius or more. I know that the manufacturer states the accuracy as 2 degrees celcius, I am sorry to tell you this but there is no way that can be anywhere close to true as I said above ten times that might be getting reasonable. The other thing to keep in mind is it has a field of view ratio of 1:1 this means that the target area expands by one inch for every inch you move away from the cylinder head. This means that you MUST get as close to the glow plug as possible because if the target area expands beyond what you are trying to measure the results will be plain wrong.

Now you ask what is a thermocouple, in short it is the thermometers that you can get that have the little wires you can hang around the cylinder head. These are realy good in many ways, because they are always attached they can record the temperatures during a lap or race, this peak temperature is far more interesting to you then the temperature of the glow plug after the engine has started to cool down. I know that a lot of people complain that the thermocouple only measures the air around the cylinder head but, this is easily fixed if you take that loop of wire and place it between the head and the screws that hold the head in place and use the screws to clamp the wire against the head. This means that you are now measuring the temperature of the head and not the glow plug but this is ok because most of the rules of thumb for tunning according to engine temperature where developed before infared thermometers where easily available and so are based on the cylinder head temperature not the glow plug temperature. If you suddenly change to using an infared thermometer you introducing another error into you measurment just because you have changed technique.

I hope this dosn't cause too much trouble but there are a lot of things to be aware of when changing to infared thermometers.


AndyT 08-01-2005 07:02 PM

Some infra-reds will allow adjustment of emissivity to allow for more accurate results......check your instruction booklet to see if yours allows for this.....I know the Duratrax Flashpoint infra reds allow for this adjustment.

Dynamite 08-02-2005 12:22 AM

Originally Posted by silacomalley

Whats a thermocouple?

a thermocouple is the measured resistance between two dissimilar metals which in our case we convert to 'c or 'f for reading temperatures.

if used how dishy explains would be the most accurate.

the amount that a motor heats/cools down would make a thermocouple which stored the highest reading the best indicator for our use. whilst many including myself are lazy and allow a little bit of fudge factor for the ease of point and shoot temperatures :D

Dishy 08-02-2005 12:30 AM

A thermocouple uses two disimilar metals to generate a voltage not resistance.

I am sorry if I am causing any trouble with my comments it is not my intention, what I am trying to do is explain to people that just because I spent x dollars on a really fancy infared thermometer does not mean that it is the best way of measuring temperature. Often the simple solutions are better.

silacomalley just keep the things that I mentioned in mind when you use the thermometer and remember with any instrument every measurment is wrong the trick is working out how wrong.


silacomalley 08-02-2005 01:38 AM

Sure. Well, I am a little clearer on a few things. I have the money to spend on something better than the cheap infra red that I have already bought, so I have no excuse. Thanks for the advice & help guys.

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