RC Engine Sizes CC & CI

Combustion engines for RC (Radio Controlled) vehicles, whether for cars or airplanes, are measured in either Cubic Centimeters (CC), or Cubic Inches (CI). In this article we will take a more in-depth view into what these measurements mean in practical terms and how to apply them to your projects.

What is a CC in Engines?

Engine sizes are usually measured in metric units. CC stands for Cubic Centimeters and is a measurement of an engine’s total displacement. In the United States you may see the use of CI, or Cubic Inches, which is the imperial equivalency of an engine’s displacement.

What is engine Displacement?

Engine displacement is a standardized measurement used to describe an engine’s size by using the total volume moved by all pistons within the engine. Although you can’t determine an engines power output or performance from its displacement, in general, it provides a rough indicator of its potential power capabilities and realistic fuel consumption range. [Displacement is usually measured in Cubic Centimeters (cm³) usually written as CC.][1]

Displacement is calculated by multiplying a piston’s travel (Stroke Length), the area of the cylinder (Bore), and the sum of cylinders in the engine.

For small radio controlled airplanes, the measurement is almost always expressed in cubic centimeters (CC) due to their miniature size.

Choosing the Right Gas & Glow Engine Sizes for RC Airplanes

CC	CI
2.0	0.12
2.5	0.15
3.0	0.18
3.5	0.21
4.1	0.25
4.4	0.27
4.8	0.29
5.3	0.32
5.7	0.35
5.9	0.36
6.5	0.40
7.5	0.46
8.2	0.46
10.0	0.61
13.0	0.80
14.9	0.91
20.0	1.20
25.0	1.50
26.2	1.60
29.0	1.77
30.0	1.80
32.8	2.00
39.3	2.40
44.3	2.70
49.2	3.00
61.0	3.72
90.0	5.49

Engine Size Conversion Formula Between Metric and Imperial

Cubic Centimeters → to → Cubic Inches
1 Cubic Centimeter = 0.06102375 Cubic Inche
Example: 5cc * 0.06102375 = 0.31ci

Cubic Inches → to → Cubic Centimeters
1 Cubic Inch = 16.38706 Cubic Centimeters
Example: 3ci * 16.38706 = 29.2cc