I took a flight to 13,500' and noticed that somewhere around 11,000' the manifold pressure started to reduce, even though I was at 100% throttle position. However, when I went to 115% power, the MP increased by the normal 4" to 5". So clearly the turbo wastegate had room to close and could make more pressure.
According to the Rotax Owner's Manual (pg 27 in the ED3 pdf):
Up to the stated critical flight altitude the respective manifold pressure is available.
Take-off performance: up to max. 2450 m (8000 ft) above sea level
Continuous performance: up to max. 4875 m (16000 ft) above sea level
If we consider that we lose approx. 1" of MP with every 1000' of altitude, then a 5" loss from 11,000 to 16,000 is *precisely* the 5" we get back when we advance to 115% power. Thus we can think that the turbo is able to produce continuous performance all the way to 16000'.
However, the graph at the bottom of https://members.gliding.co.uk/wp-content/uploads/sites/3/2020/06/LA10.engineering.V1-1.pdf (the graph is included here, but posting the link so that non-members can still see the full dialog) shows, without any caveats, that 100% throttle corresponds to 36" of pressure.
What should I expect? At 100% throttle, should the MP hold at 36" all the way to 16,000', or is it normal that it start falling off at 11,000' and when I advance to 115% I still get an additional MP boost?
