Sample Chapter
from:
"EFFICIENT POWERPLANT INSTALLATION"
6.9
Sizing of Fuel Lines
What size of tubing should you use? That depends on the maximum fuel flow of your engine, and to some extent to the length of the lines. Find out what the fuel consumption of your engine is at maximum take-off power. Unless you have an unconventional aircraft configuration, which requires very long fuel lines, the following numbers can give you a starting point:
· 4-8 gal/hour: ¼” O.D. tubing
· 8-20 gal/hour: 3/8” O.D. tubing
· 20-40 gal/hour: ½” O.D tubing
If you have an engine which requires a fuel return line, such as fuel injected Continental engines do, you will have to add the return fuel flow to the maximum fuel consumption for that engine at take off power. The detailed engine model description should contain a chart for the amount of return fuel flow. It is typically one third of the total fuel flow on Continental engines, where it is called “vapor return flow” because fuel and vapor may be mixed, so you might need a larger diameter main fuel line for a Continental engine than for a Lycoming engine of the same horsepower.