ORIGINAL: DrGsi
Idle RPM 32000 ; EGT at Idle 450 Deg ; MAx RPM EGT 590 ; Smooth running at max RPM ( No overheating problem) ; Ambient Temp in Saudi at time of test was 80 Deg F; Altitude of airfield 700 meters above sea level dry weather (10% humidity) . Things that I will change first is to put the airtrap closer to pump ; The airtrap was placed next to nose gear with fuel line coming forward from tank then backwards to pump (placed at CG) then back to Engine. The distance appears to be quite long for the fuel travel ; But if that is the reason, I should not achieve full RPM , right ? Yet I will cut down on fuel line length and check it next weekend. I can't think of something else ..All filters are brand new and clean . Could the fuel solenoid be acting Up ? It shouldn't be with a smooth start and great response to throttle stick ! We will see...... I'll get back to you next week.
Hmmm, All seems to be in order, there's plenty of temp margin too, you're right about fuel line restriction, if there was a problem you wouldn't see max rpm. Are you able to measure the tailpipe exit diameter?
I believe the nominal tailpipe exit size for the JJ1800 is ~54mm, it may be possible to go a little smaller, this will help a little with thrust but at the expense of higher EGT's, but again the thrust gains will only be very minimal. This is a strange one, most of the 1800's I've seen have all been over 18lbs @ sea level.