Advantges of Normalizing

The Advantages of Turbo-Normalizing
the Lycoming IO-360 Engine

Normally aspirated engines suffer from reduction of manifold pressure as they climb, which pilots compensate for by pushing in the throttle. At about 7,500 feet the engine runs "out of throttle". As the altitude increases, the manifold pressure decreases and the plane slows. Flying higher becomes more and more inefficient.

With a turbo-normalizer providing sea level air pressure for combustion all the way to high altitude, the loss of power and speed is delayed until reaching "the critical altitude". With the M-20 Turbo system, critical altitude is 20,000 feet, or so. Advantageously, the air speed increases as the skin friction of thinner air density decreases. High altitude capability allows the pilot the choice of:

Topping the weather
Avoiding turbulence
Maintaining terrain clearance over mountains
Seeking more favorable headwinds
Catching tail winds
More enjoyable clear air and sunshine
Navigation and communications is better --- longer line of sight
Obstacle clearance and mountain turbulence, generally 10,000 ft in the East and 16,000 feet in the West.
Safety advantage of altitude: 12,500 to 17,500 have least traffic
Added safety in an emergency from greater glide time. Area for landing increases as the square of the range

At 6,000' glide is about 7 minutes, 12.5 miles

At 12,000' glide is about 14 minutes, 25 miles

At 18,000' glide is about 21 minutes, 37.5 miles

Faster speeds mean less engine time, less avionics time and the probability of less maintenance

Faster speeds mean greater range with the same amount of fuel

High flight makes available smoother ride, colder air -- less icing risk

~ Bill Sandman ~