Valve Seat Velocities
Here's a little information that some may find interesting. I'm doing some porting and flow bench work on a SBM Speedmaster head with 2.02 valve and 50 degree seats. After about 0.500/0.550 lift, the flow backs up. I'm working on the SSR and here's some data I've gathered. The attached photos and charts show the results of pitot tube testing the velocities around the perimeter of the intake valve at eight different locations at each of seven different lifts. As can be seen, things change very quickly once the flow can no longer stay attached to the short side. At 0.600 and 0.700 lift, the flow at the chamber seat at the short side goes to zero or even reverses direction. I find it interesting that there is still high velocity flow at the short side along back of the valve at the these lifts.
This is nothing new or revolutionary, I just thought it was neat so I thought I would share it. Darin Morgan stresses the importance of minimizing velocity gradients everywhere in the system, including around the valve perimeter. I thought the numbers around the valve looked good until the wheels fell off at 0.600 lift.
Here's a little information that some may find interesting. I'm doing some porting and flow bench work on a SBM Speedmaster head with 2.02 valve and 50 degree seats. After about 0.500/0.550 lift, the flow backs up. I'm working on the SSR and here's some data I've gathered. The attached photos and charts show the results of pitot tube testing the velocities around the perimeter of the intake valve at eight different locations at each of seven different lifts. As can be seen, things change very quickly once the flow can no longer stay attached to the short side. At 0.600 and 0.700 lift, the flow at the chamber seat at the short side goes to zero or even reverses direction. I find it interesting that there is still high velocity flow at the short side along back of the valve at the these lifts.
This is nothing new or revolutionary, I just thought it was neat so I thought I would share it. Darin Morgan stresses the importance of minimizing velocity gradients everywhere in the system, including around the valve perimeter. I thought the numbers around the valve looked good until the wheels fell off at 0.600 lift.
