 Buyer Beware ...
All published cylinder head air flow figures are not equal. If you really want to compare apples to apples you can use these multipliers below to convert flow numbers to the industry standard of 28" of water. To use the chart below, simply find the "inches of water" that your flow figures were tested at in the left hand column. Then follow the line over to the right until you reach the multiplier under the inches of water that you want to know the flow at.
Let's say your flow numbers tested at 10" of water and want to know what that flow would be at 28" of water ... the test multiplier would be 1.67. Multiply your flow number by 1.67. (Look at the shading in the table below)
FOR EXAMPLE: If you have 183 cfm flow at 10" of water, multiply 183 by 1.67 and you find that you have 305.6 cfm at 28" of water.
183 x 1.67 = 305.6 cfm
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Airflow Conversion Chart Multipliers
|
| If you have flow at: |
| |
3" |
5" |
7" |
10" |
12" |
15" |
20" |
25" |
28" |
30" |
35" |
40" |
45" |
| 3" |
1.00 |
1.29 |
1.53 |
1.82 |
2.00 |
2.24 |
2.58 |
2.89 |
3.05 |
3.16 |
3.42 |
3.65 |
3.87 |
| 5" |
.774 |
1.00 |
1.18 |
1.41 |
1.55 |
1.73 |
2.00 |
2.24 |
2.37 |
2.45 |
2.65 |
2.83 |
3.00 |
| 7" |
.655 |
.845 |
1.00 |
1.12 |
1.31 |
1.46 |
1.69 |
1.89 |
2.00 |
2.07 |
2.24 |
2.39 |
2.54 |
| 10" |
.548 |
.707 |
.837 |
1.00 |
1.09 |
1.22 |
1.41 |
1.58 |
1.67 |
1.73 |
1.87 |
2.00 |
2.12 |
| 12" |
.500 |
.645 |
.764 |
.913 |
1.00 |
1.12 |
1.29 |
1.44 |
1.53 |
1.58 |
1.71 |
1.83 |
1.94 |
| 15" |
.447 |
.577 |
.683 |
.816 |
.894 |
1.00 |
1.15 |
1.29 |
1.37 |
1.41 |
1.53 |
1.63 |
1.73 |
| 20" |
.387 |
.500 |
.592 |
.707 |
.774 |
.866 |
1.00 |
1.12 |
1.18 |
1.22 |
1.32 |
1.41 |
1.50 |
| 25" |
.346 |
.447 |
.529 |
.632 |
.683 |
.775 |
.894 |
1.00 |
1.06 |
1.10 |
1.18 |
1.28 |
1.34 |
| 28" |
.327 |
.422 |
.500 |
.598 |
.654 |
.732 |
.845 |
.945 |
1.00 |
1.04 |
1.12 |
1.20 |
1.27 |
| 30" |
.318 |
.408 |
.483 |
.577 |
.632 |
.707 |
.816 |
.913 |
.966 |
1.00 |
1.08 |
1.15 |
1.22 |
| 35" |
.293 |
.378 |
.447 |
.535 |
.586 |
.655 |
.756 |
.845 |
.894 |
.926 |
1.00 |
1.07 |
1.13 |
| 40" |
.274 |
.354 |
.418 |
.500 |
.548 |
.612 |
.707 |
.791 |
.837 |
.866 |
.935 |
1.00 |
1.08 |
| 45" |
.258 |
.333 |
.394 |
471 |
.516 |
.577 |
.667 |
745 |
.789 |
.816 |
.882 |
.943 |
1.00 |
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Another helpful resource brought to you ONLY by Airflow Research and Century Performance Center, Inc.
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