Flow Bench
RHS shipped three Pro Action cylinder head castings to Westech in Southern California for us to demonstrate how these heads flow right out of the box. Here are the results as based on a 4.030-inch bore.
| 180cc Air Flow Specifications |
| Valve Lift | Intake Flow in CFM | Exhaust Flow in CFM |
| .050 in | 23.4 | 20.0 |
| .100 in | 55.6 | 48.0 |
| .200 in | 111.0 | 98.0 |
| .300 in | 158.0 | 133.0 |
| .400 in | 206.0 | 170.0 |
| .500 in | 240.0 | 189.0 |
| .600 in | 252.0 | 198.0 |
| .700 in | 260.0 | 203.0 |
| 200cc Air Flow Specifications |
| Valve Lift | Intake Flow in CFM | Exhaust Flow in CFM |
| .050 in | 31.5 | 23.0 |
| .100 in | 63.0 | 50.0 |
| .200 in | 119.0 | 104.0 |
| .300 in | 172.0 | 140.0 |
| .400 in | 216.0 | 174.0 |
| .500 in | 244.0 | 193.0 |
| .600 in | 264.0 | 203.0 |
| .700 in | 275.0 | 209.0 |
| 215cc Air Flow Specifications |
| Valve Lift | Intake Flow in CFM | Exhaust Flow in CFM |
| .050 in | 26.5 | 24.0 |
| .100 in | 60.0 | 52.0 |
| .200 in | 116.0 | 102.0 |
| .300 in | 168.0 | 134.0 |
| .400 in | 217.0 | 172.0 |
| .500 in | 260.0 | 181.0 |
| .600 in | 292.0 | 190.0 |
| .700 in | 305.0 | 200.0 |