80Stang
Well-known member
Long time no see, but here comes some interesting info to you guys:
I had the CI alum head flow tested here in Finland. The job was done by a guy that works with cylinder heads for living. I don't have doubt about the results as I know he knows his stuff, and in the past he has hand-fabricated alum heads from bare stocks of metal for rally cars. Those heads are just a few and they are very sought after today.
The valves are the ones that CI delivered with the head. Only very light work was done to chambers to grind off some sharp edges around the seats and some smoothing where the seat cutter had cut the edge of the chamber. Pocket/valve guides/runners as is from CI.
Out-of-box flow was measured 28" H2O and the head was found to be very dead until .100" lift, and then it started to flow some. I suggested testing with a back-cutted valve too and he had some back-cutted valves laying around with same stem & valve diameter. Now my intake valves are all 30-degree back-cutted, and here is why:
Lift___Improvement%
.100 25.01
.200 37.60
.300 23.81
.400 4.35
.500 5.12
.600 3.15
35* cut was tested, but 30* was found more effective.
This is to show how dramatical difference the intake back-cut affected in this particular case and at low lifts. Anyways, I'm not publishing flow numbers here, but for comparison the intake flows 67.5% of what an AFR 185 CNC-ported SBF head flowed in the same testbench 8)
The test bench is adjusted a little bit "on the tight side", so it gives realistic numbers or at least nothing too optimistic.
I had the CI alum head flow tested here in Finland. The job was done by a guy that works with cylinder heads for living. I don't have doubt about the results as I know he knows his stuff, and in the past he has hand-fabricated alum heads from bare stocks of metal for rally cars. Those heads are just a few and they are very sought after today.
The valves are the ones that CI delivered with the head. Only very light work was done to chambers to grind off some sharp edges around the seats and some smoothing where the seat cutter had cut the edge of the chamber. Pocket/valve guides/runners as is from CI.
Out-of-box flow was measured 28" H2O and the head was found to be very dead until .100" lift, and then it started to flow some. I suggested testing with a back-cutted valve too and he had some back-cutted valves laying around with same stem & valve diameter. Now my intake valves are all 30-degree back-cutted, and here is why:
Lift___Improvement%
.100 25.01
.200 37.60
.300 23.81
.400 4.35
.500 5.12
.600 3.15
35* cut was tested, but 30* was found more effective.
This is to show how dramatical difference the intake back-cut affected in this particular case and at low lifts. Anyways, I'm not publishing flow numbers here, but for comparison the intake flows 67.5% of what an AFR 185 CNC-ported SBF head flowed in the same testbench 8)
The test bench is adjusted a little bit "on the tight side", so it gives realistic numbers or at least nothing too optimistic.
