First... What Glenn said.
Plus as a very basic rule of thumb is you loose 3% of the engine performance for every 1K ft. above sea level and above standard OAT of 59F. If you tweak it for one altitude then fly to another that may set you up for a failure.
There is nothing wrong with temps in the 1400's. I just stated what the average was that I have seen over the last 20+ years. I've seen some in the 1100's and some in the 1500 range. The problem with being too high is if the right set of circumstances happen then before you can blink you'll have messed up your engine. I have seen several with trashed engines and I know Rotax has seen many too. Like I said it's a range not a specific number, but being nice to your engine makes things more reliable and long lasting. I have friends and know of many others with 3K - 4K hours on their engine because they followed the maintenance and didn't abuse or try to tweak every ounce of power to get 1 knt. of speed.
When you look at the manuals make sure you are comparing apples to apples. You have basically three engines. 912UL, 912ULS and the 914.
"I agree with you but why does rotax say 1470 is normal then. That could make the range more like 1300 to 1550 . We can also control the range with mixture"
I'm not saying you can't make adjustments depending on many things, but most don't know how all these things affect the engine and when they make an adjustment things can go very wrong in seconds and you don't want to loose that reliability. There are safe guards built in and if not many of us would be turned into glider pilots.
"I also was told Egt is more an internal temperature of the burning gas, not really affected by air temps once the engine is up to temp?"
Yes and no. Cold dry air makes a leaner mixture vs hot humid air. So if you took an engine to the extreme in the summer that same setting could cause a seizer in the cold winter air. I used to see this all the time in the 2 stroke Ultra Light days. This also depends on where your engine is getting its air. From the outside or 2 K&N air filters mounted on the carbs always getting hot air.
You have to consider all things that may affect the engine if you make a change and then decide do I want to take a chance of being a glider pilot or just go enjoy a good reliable engine and fly for the next 2K hours and not worry. You can do things to this engine, but have to reconcile with yourself if it's worth chance, money and possible failure.
Rotax has done their homework and millions of run hours in the industry. better to go with them on this and keep that engine reliability.
p.s.
If your wife is flying with you and you crash the cuts and scrapes from the crash may be the least of your worries if she finds out your alterations caused it. LOL :) .
