20 / 20
Refer to figure.
On the diagram showing the power output of a piston engine as a function of mixture ratio, best economy on rich side of the EGT top is shown at:
  • A
    point 3.
  • B
    point 2.
  • C
    point 5.
  • D
    point 4.

Refer to figure.
The air to fuel ratio that ensures complete combustion is about 15:1 by mass. It is called the chemically correct ratio or the theoretical best economy. In reality, this mixture is not the best suited for normal operations because of the high combustion temperature-induced and the increased risk of detonation. This is why the best is to set the mixture about 10% richer so that the excessive fuel absorbs some of the latent heat and cools the charge below the detonation value.

Your Notes (not visible to others)

This question has appeared on the real examination, you can find the related countries below.