hello Ryan, this is one of my favorite subjects, and i have done a significant amount of testing on this subject, using telemetry.
The 1st thing to mention is that, the value you are obtaining is highly dependant on what ever you are using to "measure" the temperature with, and where this temperature is being measured (location).
i would 1st like to say, the use of IR temp guns, in my opinion, is useless. all it tells you is the temp at the front of the cylinder, upon landing and taxing back. it does not tell you anything at all about the temperatures during flight, when the motor is under a load.
also, i have done tests with placement of sensors in different locations.
for example, a sensor in front of cylinder, low down, closer to crankcase vs higher up, closer to the spark plug.
the higher it is, the hotter the temp.
ok, same level, one sensor in front and one in the back of the cylinder (shadow of prop-wash). this will always show that the temp behind the cylinder is much higher (almost 50 to 80 degrees) higher than the temp in the front (due to effect of prop wash on front of cylinder).
interestingly enough, upon engine shut down, the temp in back stays same seconds later, but temp in front quickly rises to temp in the back, 30 seconds later, temp in front is equal to temp in back, then both temps go down together.
If you want a sensor to read the "hottest" area, then you need to place a sensor that either is part of the spark plug, or use a loop on the upper most aspect of cylinder fins, but that is touching the cylinder area. The temp you are getting on the actual "fin' itself, will be an underestimate of the real "True" hotness!!
now that i am seeing people use this sensor, i will do a test, whereby i will compare this temp to a loop with the sensor behind the cylinder.
this will give me an idea of how much is the temp difference.
Ok, here is some crazy data....
this is with a 70 cc twin motor
sensor is in the back of the cylinder, uppermost area (hottest area).
the motor runs well with temps in 300 range. If temps get into 380 range, still runs well, no fading or hiccuping.
once motor gets into 400 range, still seems to run ok, but the moment it gets to 450 F, it will fade, meaning, 1/2 stick, it loses power, if i throttle up, "DEADSTICK!"
ok, some cool info:
temps are constantly fluctuating during flight.
there will be temp peaks and valleys.
if you fly level, temps can be in 250 range, if you do a long upline, temps can rise to 320 F.
any type of hovering, knife edge flight, knife edge spins, flat spins, etc... where the motor is revving up, but there is less air movement, will really heat up the motor.
ok, you are flying, doing sport stuff, the moment you get ready to make approach to land, temps will decrease by 50 degrees or so, when you are locked on to land, and are gliding in, the temp is the lowest, this is when airplane is descending, and has a good speed, and the motor is idling. there is good air movement in the cowl, and the motor is under least amount of load, this is a time the motor really cools down. Upon landing and then taxing back, temps will go up a bit, maybe 20 degrees or so, from what i recall.
anyways, hope this info helps.
i would say, be aware, where your temp sensor is, it is not giving you a pure real world exact reading of how hot it is really getting, so you may have to add some more degrees (which i will investigate to get this number).
best regards!!
