I've heard that the onboard ones can fry and give inaccurate readings...
I believe engine would be running hotter at idle when you bring it in
anyway because air is no longer flowing over the head. I doubt any
significant heat change will occur in the 5 seconds it takes to use the
All in all, I'm happy with my infrared sensor, and I'd prefer to keep
my equipment safe in my pocket rather than bouncing around in my truck.
I'm sure with either option, as long as you keep the engine from running too hot both will do the job.
Honestly, tuning your engine with a temp gun is typical yankee marketing b-s. It is the crappiest way of doing it.... when you can do it perfectly well by the sound (should rev cleanly) & smoke (no smoke = too lean).
When nicely tuned, engine temp will vary depending on the surrounding weather and humidity. You can't expect the engine to maintain the same temperature in summer and winter... it don't have a water jacket, radiator & thermostats.
You *need* to retune if the weather conditions change - it is not "set-n-forget".
These days there's lots of cheap keyfob-sized units -don't know how well they work, haven't tried them. 10yrs ago we were checking engine temps with a thermocouple-equipped multimeter. Works great, but it needs 'contact'.
Again, it real misleading to tune engines by temp.
I bought a Raytek about 5 yrs ago, that's what the professionals use outside of RC. I have checked a few nitros with it... but just because you know what temp it is doesn't mean if its tuned right & definitely can't tune anything with it. Especially if you got your reference off someone in North America (hellooooo, half a globe away!!!).
Raytek has seen use everywhere, from garage to kitchen. I bought it when I just needed a new toy to play with, but its been a great diagnostic aid -we've used it to:-
<LI>find out a sticking 1:1 brake drum/disc... check all 4 temps & compare</LI>
<LI>bad 1:1 plug, wireor dizzy? One cylinder will be colder than the others.</LI>
<LI>aircon & heating ducts leaking? easy.</LI>
<LI>powercord on your heater gone dodgy? Find the hot spot!</LI>
<LI>we use it more often to check battery/motor/ESC temps in electric</LI>
<LI>use it to check temp of the track tarmac (for tyre choosing)</LI>
<LI>frying steak? Heat pan to 175degC = perfect!!
<LI>been making home icecream too... need to chill mixture to -1.0degC.</LI>[/list]
So yeah, a IR gun is much more useful than the Venom hanger-on thingy.