High altitude tests on 5900 ft

[flyover1974]

Hi Pilots,

today i had time to test on ground high altitude on 5900 Ft my 45 hp diy engine.
the prop is a handmade 54x 23,5 inch wide blade wood prop.
For specs of my engine see here:
i got 2800 rpm and 1100 F and 160 pound thrust.
Airtemp was 68 F.
What do you think the rpm goes up to 3200 on 1000 ft and 200 pound or more?
I can not test on low altitude because i live in the center of the european Alps mountains and to get under 2000 ft i need to go very far away.

than i have a strange problem with the ngk B6HS spark, it is white and seem too lean but the EGT is low at 1100 F...

i dont know what is right now, to use for maximum power the spark plug or EGT.
Edit:
On the engine pics you see where the EGT is located, around 2 1/2 inch away from the cylinder exhaust flange

Cheers
Hermann

[Richfroh]

The spark plug looks like the mixture is lean. When the mixture goes leaner than peak EGT, the EGT's will drop. My suggestion is to richen the mixture in small steps and monitor the spark plugs and EGT's with each change. If the EGT's rise with richer mixture, then you are lean of peak. Keep going richer until you get about 50 degrees drop in EGT which is on the rich side of peak EGT.

[flyover1974]

Thank you Rich.
Maybe i found the problem. I had more than 40 degree spark advance...
Now i set the 009 at 6 degree advance at idle, so including the 24 degree speed variable of the 009 i have max 30 degree. Tested today at 2000 ft and the spark look good
than i was surprised about the static thrust:
2000 ft altitude
Air temp 95 F
2850 rpm
EGT 1100
....and the thrust is amazing
see the pics of minimum and maximum thrust

[flyover1974]

Video of the test assembly today:
The rpm indicator on the MGL Stratomastet display is not connected, it shows wrong rpm.
The right rpm is the small black hobbs and rpm above on the right.
All numbers are in Celsius and Bar.





And spark plug color. Looks perfect now 😊

[glenn woloski]

What is the ignition system you are using?