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Old 09-14-2009, 05:54 AM   #1
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Default temp gun accuracy

Yesterday at the track I pulled off the track and a fellow racer zapped my temp with his exergen and it came back like 220. I do next qualifier and check it with my Raytek...250. No changes in air temp, etc. I don't tune just to temp, but like to have an occasional reference point. Whats up with the variety in readings? When I used my o'donnell it was always reading lower then my raytek, but I trusted more towards the raytek...
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Old 09-14-2009, 07:47 AM   #2
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I've always wondered the same thing. I can tell you the losi temp and tune has been the farthest off that I've seen. I temped mine with it and it was 219f and friend of mine that was standing right there temped it with his exergen and it was actually 184f. But I guess I'd rather have it reading high then low. I have 3 temp guns the raytek,losi and duratrax and there is usually a 15-20 degree difference between the 3. And don't even try the duratrax on a new shiny cooling head! That is just a waste of time! What's the point of buying one if they are that far off?? Hell, what's to say the exergen is even right??
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Old 09-14-2009, 07:57 AM   #3
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Most are different, thats why when Im tuning, I use my gun only
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Old 09-14-2009, 10:06 AM   #4
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None of my temp guns have been all that reliable. I use them to double check what I allready know.

Nowadays, I just lick my finger and wipe some spit on the cooling head. You should be able to see the wet mark you made on the head for a second or two. If your above 280 that wet mark won't stay there at all.

I tune to performance only, and watch for smoke. Temp guns are useless.
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Old 09-14-2009, 01:14 PM   #5
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Yep if it is over 280 Spit wont stay but Skin will .
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Old 09-14-2009, 02:07 PM   #6
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I dont use a temp gun anymore. The only one you can really trust is the Exergen and its just too expensive for me.
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Old 09-14-2009, 03:02 PM   #7
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To check your temp gun. Boil a pot of water. Right when the water starts to boil temp it with your gun. At sea level water boils at 212 degrees. That the most accurate way to check you gun hope it helps
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Old 09-14-2009, 03:10 PM   #8
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Originally Posted by gkn0315 View Post
To check your temp gun. Boil a pot of water. Right when the water starts to boil temp it with your gun. At sea level water boils at 212 degrees. That the most accurate way to check you gun hope it helps
I've thought of that (I need to find out when water boils at my elevation) but can an IR gun really read moving water?

I can't think of any other naturally occuring constant temp to use unless I want to stick it in my butt.
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Old 09-14-2009, 03:23 PM   #9
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I've thought of that (I need to find out when water boils at my elevation) but can an IR gun really read moving water?

I can't think of any other naturally occuring constant temp to use unless I want to stick it in my butt.
Nope, no way. I have a dozen temp devices at work. Only probes connected to a DVOM are accurate to +/- 20.

The IR guns lens just fogs over if you temp the water in the pot. Not to mention water in a silver pot looks alot different than a cylinder head.

You can measure the side of the pot. But I've still had varying degees on success with that. Then your temping the pot and not the water, they aren't going to be the same.

Use a THIN aluminum pot and temp its side with the pot of boiled water off of the burner, let the pot sit a bit before you temp it, water deosn't cool that fast.

Best thing about this test is you'll be alot closer to your kitchen garbage can.
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Old 09-14-2009, 03:33 PM   #10
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Best thing about this test is you'll be alot closer to your kitchen garbage can.
LMAO..
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Old 09-14-2009, 03:37 PM   #11
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If I didn't have a temp gun I would burn up my engine for sure. Not new to nitro engines but new to nitro in a car.

On airplanes it's so much easier. Just go WOT and turn the needle to the rich side of max rpms. Not to mention that the whole time you are using it, you are flying through the cooling air.

Cars are driving me nuts learning how to tune them.
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Old 09-14-2009, 03:42 PM   #12
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The way I found out how close or not my temp gun was, is to get a friend with a exergen and get a soldering iron. Get the soldering iron going and temp it with the exergen and your temp gun at the same time. Then just compare the difference. Thus worked out well on 2 out of the 3 temp guns I got. That damn duratrax will be within 10 degrees at one point and then 40 degrees off further up the line!
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Old 09-14-2009, 04:20 PM   #13
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Originally Posted by AndysD8 View Post
I've always wondered the same thing. I can tell you the losi temp and tune has been the farthest off that I've seen. I temped mine with it and it was 219f and friend of mine that was standing right there temped it with his exergen and it was actually 184f. But I guess I'd rather have it reading high then low. I have 3 temp guns the raytek,losi and duratrax and there is usually a 15-20 degree difference between the 3. And don't even try the duratrax on a new shiny cooling head! That is just a waste of time! What's the point of buying one if they are that far off?? Hell, what's to say the exergen is even right??
A friend of mine had the same issue with the Losi Temp and Tune as you did. His was a good 20-30 degrees higher then it should of been. I have actually had good luck with my blue Duratrax temp gun. It is a couple degrees off the really high end temp guns but good enough to get a idea of how your motor is running.
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Old 09-14-2009, 05:22 PM   #14
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A friend of mine had the same issue with the Losi Temp and Tune as you did. His was a good 20-30 degrees higher then it should of been. I have actually had good luck with my blue Duratrax temp gun. It is a couple degrees off the really high end temp guns but good enough to get a idea of how your motor is running.
Exact same situation here.. I bought the DTX when I got my Revo and figured it's probably not too accurate. Then I bought the 8B RTR and didn't want to depend on the telemetry or the DTX temp gun so I bought the Losi temp-tuner. Turns out the Losi gauge is way off compared to everyone elses guns at the track. Both the DTX and the onboard telemetry are in sync an coincide pretty closely with others guns at the track.

I'm sending my Losi in for warranty replacement, but I dont think it will make a difference.
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