TF & Speedmaster Flow Tests
Back on the Speedmaster head with a few changes. I increased the width of the port on the cyl center side at the apex which brough the velocity at the apex of the SS down to 360-380 range. It was almost 410 at peak. Flow did not change much, maybe down 5 cfm from previously. I also undercut the chamber a little where most shrouded, but stayed with the 4.07 bore circle. Flow increased a little in the 0.200-0.400 range, but decreased a little after that. Test 495 shows the result of those modifications. Seat was still 50 deg, throat remained in the 91-91.5% range.
Next, the throat was epoxied up and the valve job redone at 35/45/60/75 and blended to 88% wide and 89% SS to long side. Seat angle is now 45 deg. This was mostly a loser, but the throat is still a little small and I'm not happy with the shape yet. Test 497.
Before enlarging the throat and eventually going back to 50 deg seats, I decided to lay back the center of the SSR. I probably removed 0.020" at the center and blended it into the existing sides. I also did some very minor touch up to the cyl wall side of the throat which increased the throat size to 89% in both directions. Laying back the SSR did help a little at higher lifts, and I noticed that flow was trending upward at 0.750, which is the point I usually stop testing. This time I went to as high a lift as the valve would allow, which was 0.950. The flow continued to be stable and slowly increased with increasing lift.
I'm not exactly sure what this means, but I think it is a positive trend. I would still like to get the dip at 0.600-0.700 out of the curve.
Back on the Speedmaster head with a few changes. I increased the width of the port on the cyl center side at the apex which brough the velocity at the apex of the SS down to 360-380 range. It was almost 410 at peak. Flow did not change much, maybe down 5 cfm from previously. I also undercut the chamber a little where most shrouded, but stayed with the 4.07 bore circle. Flow increased a little in the 0.200-0.400 range, but decreased a little after that. Test 495 shows the result of those modifications. Seat was still 50 deg, throat remained in the 91-91.5% range.
Next, the throat was epoxied up and the valve job redone at 35/45/60/75 and blended to 88% wide and 89% SS to long side. Seat angle is now 45 deg. This was mostly a loser, but the throat is still a little small and I'm not happy with the shape yet. Test 497.
Before enlarging the throat and eventually going back to 50 deg seats, I decided to lay back the center of the SSR. I probably removed 0.020" at the center and blended it into the existing sides. I also did some very minor touch up to the cyl wall side of the throat which increased the throat size to 89% in both directions. Laying back the SSR did help a little at higher lifts, and I noticed that flow was trending upward at 0.750, which is the point I usually stop testing. This time I went to as high a lift as the valve would allow, which was 0.950. The flow continued to be stable and slowly increased with increasing lift.
I'm not exactly sure what this means, but I think it is a positive trend. I would still like to get the dip at 0.600-0.700 out of the curve.
