At Atwood Performance, all sets of heads leave with a flow test sheet. As can be seen in the picture, flow testing is done on a SuperFlow SF600 professional model flowbench. The cylinder heads are flowed through an actual Harley Davidson cylinder to simulate the way the head will flow while actually bolted onto the bike. All tests are performed at the industry standard of 28" water depression for accurate comparrison to others. Intake tested with 3/4" radius inlet. Exhaust tested with 1 3/4" X 6" exhaust pipe.

     Atwood performance takes great pride in being extremely accurate with flow test results and encourages private testing for verification.

Flow test examples:

Stock 99 casting:

                  intake        exhaust

• .100     64.7          46.1    
• .200     122.4        102.2
• .300     171.5        142.9
• .400     191.3        160.6
• .500     189.3        168.5
• .600     189.7        171.4

Stage I port on 99 casting with stock size AV&V valves:

                  intake        exhaust

• .100     68.2          56.2    
• .200     133.5        116.9
• .300     191.0        163.9
• .400     231.5        187.5
• .500     247.9        199.5
• .600     251.4        205.5

Road Warrior 1.900 on 99 casting:

                  intake        exhaust

• .100     68.7          51.4
• .200     133.5        123.2
• .300     195.4        170.2
• .400     235.6        197.9
• .500     255.4        210.6
• .600     265.4        213.4