dallarax19 wrote:I would appreciate input. I have the start of a PRV simulation and would appreciate any feedback and clarification on exact geometry. We estimated the following:
1) Port diamter, at the head and at the valve seat
2) Rocker ratio and cam lift (1.5?)
3) Cam center line (108?)
4) Cam profile / lift
5) Cfm of the carbs
I’ve taken some dimensions of the cylinder heads of my A310 and these are the results:
Regarding your questions: -
1. Port diameter at the head and valve seat. See items 6 & 7 below.
2. Rocker ratio and cam lift.
Using a depth micrometer mounted on the top of the head I measured down to the back of the cams and then to the top of the cam lobes, the difference being the cam lift. The measurement was reasonably accurate and varied between 0.198” to 0.205” (5.03 mm to 5.21 mm) plus or minus a couple of thou. This was approximately the same for both inlet and exhaust valves and the 2 heads.
I measured a rocker, which was 48 mm from the shaft centreline to the adjuster and 30 mm from the shaft centreline to the edge of the wear mark on the follower, thus giving a ratio of 1.6.
Using the measured cam lift range above, this gives a valve lift of 8.05 mm to 8.34 mm. This equates approximately to the 8.17 mm and 8.3 mm stated in the A310 manual and in your tabulation. However in your 2.7 ltr base power simulation plot the ‘Setup’ notes assume a valve lift of 12.45 mm based on a cam lift of 8.3 mm.
As a double check I put an inlet valve in a head and measured the actual lift of the valve and it was approximately 8 mm.
This is the only comment I have against your plots, all the data in you tabulation agrees with the data in the A310 manual.
3. Cam centreline. If you mean the height of the cam centreline above the head/block split line face then mine measures 84mm. I’ve seen some data somewhere that gives the cylinder centreline spacing as 108 mm.
4. Cam profile/lift. See 2 above. I don’t have any dimensional data regarding the actual cam profiles.
5. I don’t have any carb cfm data.
6. Intake port dimensions.
Using the same nomenclature as your post of the 27th December.
A = 39.5 mm, B = 36 mm, C = 42 mm parallel to head face (horizontally) and 43 mm perpendicular to head face (vertically), D = 37 mm but difficult to be accurate as the port shape at the manifold is quite varied, horizontally and vertically, and each of the 3 ports differ in shape.
I didn’t measure the port length because I wasn’t sure of your end point in the manifold.
7. Exhaust port dimensions.
A = 32 mm, B = 34 mm parallel to head face, in the perpendicular direction the port is restricted by the casting bulge around the valve guide and the bulge opposite to this, C = 31 mm, D = 29 mm.
Again I didn’t measure the port length.