Ok, went to the field today. Checking 5 props is a bit of an effort. Installed the prop, tuned by ear 1/4th turn back from peak, ran for about 30-45 seconds each time and then took the readings. There was no one to help me, so it was a bit awkward because everything shakes including my hands, and I am not able to perceive the tone change for last 10% tuning, so results may not be 100% accurate. Got the following results with a tachometer and infrared gauge

13x7APC- RPM 11200 Temp on cyl head 100Deg C

14x4MAS- RPM 13100 Temp on cyl head 103Deg C

14x6MAS- RPM 10400 Temp on cyl head 110Deg C

14x8MAS- RPM 8400 Temp on cyl head 104Deg C

13x6MAS S2- RPM 11500 Temp on cyl head 122Deg C

The readings are in chronological order. Note that the temperatures drift a bit. This may be because I tested one prop after other only a couple of minutes apart- about the time it takes to take off one and install the other without spinner. Also, I initially got a 127 Deg C reading on the 14x6 but after the 14x8 gave me a lower reading, I tried the 14x6 again and got a lower reading. Also, each time I noticed that the engine have very soft compression after I had just run it for a minute, no matter what the prop

Note all of that was with the 10% nitro mix. It took an hour for me to do all of that in the 38 Deg C heat and I was too fed up at the end of it. Also, so many people on the field and not one person came to help me which was extremely disheartening. All those people who would regularly help me wer not able to make it today.

Nonetheless, I did it, then realised that I need to fly anyway, now that I was on the field. Still had the 13x6 on it at the end. So, just to check if that helped, I pumped all the 10% nitro fuel out and put in the plain synthetic fuel I had blended the night before. With that I tested the engine, tuned as before and took-off. Engine remained operational the entire flight. Did seem to loose some power marginlly when vertical but that could be due to the tuning (like I said I cant perceive the last 10% of tuning). After I landed and taxied in, I took a temperature reading immediately after I cut the throttle and that was 84 Deg C. Subsequently, I installed the 13x7 again and flew twice more. In the 3rd flight I tried hovering. Since the engine was 1/2 turns rich from peak (I didnt have a helper to hold her vertical so I could tune for hovering so I set it 1/2 turn out from peak), the airplane responded a bit late to throttle and (by then) there was a stiff sea breeze that kept pushing it around. I noticed that it would start to wing rock which I couldnt correct with any control and when I added throttle at 60%-70%, she would simply climb. When I landed, I put my finger on the crankcase and was able too keep it there without too much discomfort. Remember, touch down and taxi was about a minute.
Phew that was a lot of typing but I described everything that happened

Now my inferences

1) There was something wrong with the 10% nitro fuel. It could either be too much nitro for the conditions or hydrolysed methanol or something else

2) The 13x7 is not suitable for hovering, need to put the 14x6 or 14x4. Leaning towards the 14x6 for better hybrid performance and because the 14x4 gave a 13000+ rpm

Any inferences you can draw?

Regardless, I will be ordering a DLE20 and opening up a Phoenix Extra 330S for that engine (or the 120ax) very soon

Ameyam