How to take temp?

[DougJorgie]

This may sound like a stupid question but I have to ask it. What is the correct way to take the temp of an engine with an infrared pistol grip temp gun? Is it like this...

Or like this...

I had to ask this question because I am getting a 100 degree difference. The first way i am getting temps 300+ and the second way is giving me temps of 220-250. I am getting these temp while the truck is running great...good smoke, good performance, etc. This whole time I think I am having an overheating issue, but maybe I am not. Maybe I am just taking the temp wrong.

 

[joshman1204]

You need to do it the way you have it in the first pic. The temp gun should be touching the head with the sensor in the middle of the head directly over the glow plug.

 

[DougJorgie]

You need to do it the way you have it in the first pic. The temp gun should be touching the head with the sensor in the middle of the head directly over the glow plug.

If this is the case then my engine is running great at 340? I even saw 370. I dont understand?

 

[avelciario]

That is too hot. It will run great cause your in a lean side, your engine is already overheating. 370F is tooooooo hot bro. Tune it in performance but let the temp as your guide also, for me all my nitro run only 220 to 240F.

 

[Mn Monster]

cut some air flow holes in your front windshield that will help a little, but if your temps are that that hot, your running lean or my have an air leak issue.

 

[DougJorgie]

cut some air flow holes in your front windshield that will help a little, but if your temps are that that hot, your running lean or my have an air leak issue.

I sprayed WD40 around the whole engine and carb while it was running and the idle did not increase at all. I used to have a big air leak in the fuel tank. Th cap wasn't sealing at all from the factory. It was like this during break in. Could this have caused a problem with the engine that is causing these high temps?

 

[Mn Monster]

did you monitor your temps during break in ? can you see bubbles in the fuel line ?

 

[DougJorgie]

I did not monitor the temps during break in and I do not have bubbles in the fuel line. I thought I had bubbles but I dont.

 

[SchrodeMode]

I've always done mine the second way, so has every other person I've seen.

 

[Zdragon71]

^^^me too. I've never touched the head of engine with my gun to read temps. Always held it just above and pointed laser just off the edge of glow plug for best accuracy. Also i do recommend cutting out the windshield and back widow area for better airflow to engine.

 

[Greywolf74]

I use a smaller pocket sized temp gun. can't recall the name of it right off but its similar to a Duratrax flashpoint. I have to hold that one right on the head to get accurate readings. I bought a cheap gun that is the same "gun" type like you have but I pitched it cuz it was very inconsistent.

 

[joshman1204]

Taken from http://tempgun.com/faq/how-to-use-a-tempgun/#10

How do I measure RC engine temps with the laser models?

You must keep in mind that the laser is offset one half inch from the center of the infrared sensor, and runs PARALLEL to the sensor. This is an important detail for close measurement!

and some more

How do I use the Pro Exotics TempGun to measure my RC engine temps?

When temping out the engine of your Nitro car, you are looking for the highest current reading. That highest reading is typically going to come from your glow plug, and you can usually hit it from right over the top of your engine. Hold the “measure” button down on your TempGun, and pass it over the top of the engine. Get right up on the engine, so that you are just about touching the head. Holding down the button gives you continuous feedback, note the highest reading that you get, that is the number you are looking for.

With the PE2 unit , you can shoot engine temps from a farther distance because of the tighter D:S ratio of 6:1. The PE2 unit is good for cars with high riding bodies, or where the engine is buried down in there and tough to access. From a distance of 4 inches, the PE2 will measure a spot just one half inch in diameter.

With a moderately warm Nitro engine, you are likely to see temps in the 180-210°F range. With a car that has been running hard for a while, you will start to see the engine creep north of 230 or 240°F. If you go much higher than that, you risk melting a hole in the earth’s crust, or at least blowing your engine, so know your car’s limitations! Get to know the parameters of your own car and engine to fully understand what will be the best operational temps for your individual situation, whether it be backyard bashing or serious racing.

As a note, also consider using the “Max” feature of the Pro Exotics TempGun. For the TG1 and PE2 models, hit the “measure” once to turn the gun on, and then hit the mode button twice to enter the “Max” mode. This way, as you hold down the measure button and pass over your engine, the TempGun will grab the HIGHEST reading and hold it until it sees something even hotter.

And finally

How do I aim my TempGun using the laser?

For our models PE2 and PE-3 , aiming from a distance is made easier by use of a red sighting laser.

The red laser is offset from the TempGun’s infrared sensor by one half inch. The laser runs PARALLEL to the center of the sensor. This means that from 3 inches away, the laser is one half inch from the center of the temperature measurement. From 20 feet away, the laser is STILL one half inch from the center of the temperature measurement.

This means that from a very close distance, say three inches or less, the laser IS NOT going to be at the dead center of your measurement, ya dig?

In the RC Hobby, measuring nitro engine temps, you are trying to measure a spot a quarter inch wide down inside the head of the engine. This is typically done by putting the TempGun (regardless of brand) directly over the top of the head. If you do it that way, your sighting laser will be cast one half inch off to the SIDE of the head, and not down the middle at all. THAT IS FINE. Your concern should be with the positioning of the INFRARED sensor at that close range, and not the goofy laser. If you do indeed shoot the red laser down into the head, you will actually be measuring a half inch away, probably down the side fins of your engine. Do you dig it now?

The sighting laser will ALWAYS be one half inch from the center of your measurement. For those insistent customers, I will custom build a parallelogram reflective mirror system, in a snap on configuration, that will compensate for this offset, so that regardless of distance, the laser is always spot on, dead center. The fee for this custom accessory is 5 million U.S. dollars, payable by certified funds two weeks before start of production. Better get in line for that add-on right now!

NOTE: The red laser that is available on some of our TempGun models DOES NOT measure temperature! It is a separate beam that simply serves as a pointing device. The surface temperatures are measured using an invisible infrared sensor. The red laser can shoot a very long distance, across the hall, across the building, across the street. The INFRARED sensor only shoots (effectively) a short to medium distance, depending on the model’s D:S ratio. So while you can use a “laser gun” and see a red dot on the wall 50 feet away, you ARE NOT measuring the temperature of that far away wall, but rather a general average temperature of a large area (from 50 ft). No infrared TempGun is any good at measuring empty air ambient temperatures.

 

[Snook Man]

I am an Infrared Thermographer by trade.

Having experimented with many different IR temp guns comparing them against certified IR cameras capable of detecting temps to 1/3 of a degree F, there are many variables to contend with for both the Handheld IR temp gun and the very, very expensive IR cameras. Emissivity and distance being the 2 biggest factors. 100 degrees F difference in your handheld at that difference in distance tells me the spot ratio size of that gun is very sensitive to the distance from the temperature source.

Other guns (same model/same manufacturer) or (different model/different manufacturer) may not be as sensitive to the distance or may be even more sensitive. The only way you will know for sure if the temp reading is close to the actual temp for any given surface/temperature source at any given distance would be to compare the IR gun reading with a Thermocouple Temperature Measurement Sensor or similar device attached to the temperature source.

If the engine is running well with good smoke and performance, chances are you are not overheating.
Too many people fall into the temperature trap and don’t get to enjoy the hobby.
Don’t forget about the old reliable spit test us old timers still use even when we have a couple IR guns in the pit box. No emissivity or distance to worry about with your spit. It either sizzles away too quick (too hot) or just sits there looking back at ya (too cool).

 

[Mn Monster]

I've always done mine the second way, so has every other person I've seen.

same here.

---------- Post added at 7:04 PM ---------- Previous post was at 7:03 PM ----------

I did not monitor the temps during break in and I do not have bubbles in the fuel line. I thought I had bubbles but I dont.

cut some holes in your lid for better air flow and check your temps again and see where they are.

agree with Snook, if your motor is running good, good power, smoke trail ect. ! have fun with it, i still check my temps when i'm hill climbing or running in taller grass to just make sure my mill is not getting to hot.

 

[mrbones]

Doug, You are putting way too much thought into this temp gun business. I am no expert but let me tell you where I''m coming from. I run with about 7 guys who have been running nitro engines since they started making them and believe me, these guys know what they are doing. To this day, I have never seen one of them pull out a temp gun. I have a temp gun because when I started, I thought I needed it. Now that I have learned what I'm doing, (or at least think so!) if I wanted to use it, I would probably have to go find it. I am running about 10 different engines. If someone offered me $100 to tell them what temp any of them are running, I couldn't tell them because I don't know. What you need to do is seal up your engine so that it won't suck air. Then you need good air flow across the engine so cut out your windshield. Then you keep increasing your fuel until it starts to bog a little and then back it off a little. You might then need to go back and re-adjust your LSN. You need to be running a good name brand fuel that contains a blend of castor and synthetic oil. (The synthetic is for high rpm and the castor will protect you at high temps.) Throughout the year, you will need to adjust your fuel. In winter, spring, and fall the air density is high (containing more oxygen per cubic volume) so it chews up your fuel and will cause it to lean out a little. You can then increase the HSN and put more in it. In the summer when it gets warm, the air is thinner (containing less O2 and probably a bunch of humidity) and you have to reduce the amount of fuel you're putting in it to get the same performance. And you need to always have a clean air filter. So get it running, put it out there and run the fool out of it. You can still shoot it with the gun to see what it's doing but don't be concerned with it too much.

 

[mrbones]

And so today, since were are talking about it, I got out the temp gun (which was in my work bag because I've been using it at work as a laser pointer). I got out my 2 speed XTM buggy and ran it. It's set up to run on the road. I'm running a Sirio Monster big block 27 w/ Byrons 25% fuel. When I brought it in to shut it down I shot the temp and it said 285F. So now I know.

 

[DougJorgie]

This makes me feel more confident that my truck is running good. I was also thinking about how I run my truck. I run mostly in grass and half of the area I go is an incline so it is up hill in grass with a lot of wot running. My next time out I am going to go to a parking lot and run on flat pavement and see how it does.

 

[mrbones]

This makes me feel more confident that my truck is running good. I was also thinking about how I run my truck. I run mostly in grass and half of the area I go is an incline so it is up hill in grass with a lot of wot running. My next time out I am going to go to a parking lot and run on flat pavement and see how it does.

I ran my tmaxx in heavy grass one day and I thought I smoked the engine. I also took it to the park and ran in tall grass going up a hill and almost smoked it there too. Now I stay away from tall grass. Wait until you go to the parking lot and see how it does. It's probably running just fine.

 

[DougJorgie]

Thanks for everyone's help. I am new to nitro and, like Mr. Bones said, I tend over think things. I will report back after I get a chance to run in a parking lot.