Engine Compression Ratio Calculation

How to calculate Compression Ratio
Forumla – Head cc = Deck cc = 1 cylinder volume Head cc + Deck cc
Example – 69mm X 90.5mm engine size = 1775 ÷ 4 =443.75cc
.060″ Deck =9.80cc
Head =_____50.00cc
503.55cc
Compression Ratio Chart
1300, 1500, 1600cc Type I, II & III Single & Dual Port Heads CC in Head – Depth of Flycut
Bore X Stroke
|
37cc
.140 |
39cc
.120 |
41cc
.100 |
43cc
.080 |
46cc
.050 |
51cc
varies |
Engine Size
|
85.5 x 69 |
9.68
|
9.31
|
8.98
|
8.67
|
8.25
|
7.64
|
1584
|
85.5 x 74 |
10.32
|
9.92
|
9.56
|
9.23
|
8.78
|
8.13
|
1699
|
85.5 x 78 |
10.82
|
10.41
|
10.03
|
9.68
|
9.20
|
8.51
|
1791
|
85.5 x 82 |
11.32
|
10.86
|
10.49
|
10.12
|
9.62
|
8.90
|
1883
|
87 x 69 |
9.91
|
9.54
|
9.20
|
8.88
|
8.45
|
7.83
|
1640
|
87 x 74 |
10.56
|
10.16
|
9.80
|
9.46
|
9.00
|
8.33
|
1760
|
87 x 78 |
11.08
|
10.66
|
10.28
|
9.92
|
9.43
|
8.73
|
1855
|
87 x 82 |
11.60
|
11.16
|
10.76
|
10.38
|
9.87
|
9.13
|
1950
|
92 x 69 |
10.76
|
10.36
|
10.00
|
9.66
|
9.19
|
8.52
|
1835
|
92 x 74 |
11.46
|
11.04
|
10.64
|
10.28
|
9.78
|
9.06
|
1968
|
92 x 78 |
12.02
|
11.57
|
11.15
|
10.77
|
10.25
|
9.49
|
2074
|
92 x 82 |
12.59
|
12.12
|
11.68
|
11.28
|
10.73
|
9.93
|
2180
|