CNC Mill Mark Removal in Intake Port
Here's a post to clean up a few loose ends from yesterday. Included is a picture of my plywood entry plate and how I use clay to blend any mismatch with the head. Also included is a picture of my manual valve opening jig. I've found it to be quite rigid and repeatable. There are countless ways to do both the entry plates and the openers. They have to be customized for each new family of heads.
With the flow tests I want to address two issues. The first one is repeatability of the flowbench (this is different from accuracy). Tests 593 and 594 were run back to back on a new, untouched, factory CNC port with no changes in between the two tests. The head was not taken off the bench. Bench temp was 76.5 for the first test and 77.6 for the second test. The vacuum motors inside the flow bench heat the bench up slowly when running intake ports and very quickly when running exhaust ports. When running intake ports the heat from the motor inefficiency is exhausted out the back of the bench. On exhaust ports this heat travels through the bench and out the head. Anyway, as can be seen, the repeatability was 1.4 cfm or better. Pretty good for a system measuring turbulent flow.
This test shows the bench is quite repeatable. Most benches are calibrated (for accuracy) by the user on occasion with an orifice plate that comes with the machine. I suppose this yields decent accuracy, but for most of us it doesn't really matter. For most flow tests, I am looking for the change from one test to the next. I want to know if the little bit of grinding or little bit of epoxy I just added helped or hurt. Accuracy would be nice, but it's not worth the trouble. Repeatability is what I want.
The last test 595 is a flow test done after sanding the short side only of the same port used in 593/594 with 180 grit paper. So, the head was removed from the bench, the intake valve removed, and the SSR sanded. The plywood entry plate was not removed. As can be seen, flow picked up a little.
Here's a post to clean up a few loose ends from yesterday. Included is a picture of my plywood entry plate and how I use clay to blend any mismatch with the head. Also included is a picture of my manual valve opening jig. I've found it to be quite rigid and repeatable. There are countless ways to do both the entry plates and the openers. They have to be customized for each new family of heads.
With the flow tests I want to address two issues. The first one is repeatability of the flowbench (this is different from accuracy). Tests 593 and 594 were run back to back on a new, untouched, factory CNC port with no changes in between the two tests. The head was not taken off the bench. Bench temp was 76.5 for the first test and 77.6 for the second test. The vacuum motors inside the flow bench heat the bench up slowly when running intake ports and very quickly when running exhaust ports. When running intake ports the heat from the motor inefficiency is exhausted out the back of the bench. On exhaust ports this heat travels through the bench and out the head. Anyway, as can be seen, the repeatability was 1.4 cfm or better. Pretty good for a system measuring turbulent flow.
This test shows the bench is quite repeatable. Most benches are calibrated (for accuracy) by the user on occasion with an orifice plate that comes with the machine. I suppose this yields decent accuracy, but for most of us it doesn't really matter. For most flow tests, I am looking for the change from one test to the next. I want to know if the little bit of grinding or little bit of epoxy I just added helped or hurt. Accuracy would be nice, but it's not worth the trouble. Repeatability is what I want.
The last test 595 is a flow test done after sanding the short side only of the same port used in 593/594 with 180 grit paper. So, the head was removed from the bench, the intake valve removed, and the SSR sanded. The plywood entry plate was not removed. As can be seen, flow picked up a little.