My Pro Topline BBC Flow Numbers
I had posted earlier that I would share the flow numbers on my heads that will be going on my 489. These are 320cc aluminum with a bowl blend and gasket match and blended chambers. I only flowed two cylinders #5 and #7 for a comparison. They were flowed on a Flow Lab 520 with a 4.310 bore fixture(all the way through). This flow bench locates the head with a head gasket just like it would be bolted on the block. I mention that because the flow bench I used to use was a Superflow 400 and it was not this way. You could move the head around on the fixture. It is also computer controlled and calibrated.
#5 Intake:
215.2 @.300
270 @.400
342.3 @.500
374.7 @.600
395.9 @.700
406.5 @.750
#5 Exhaust
157.8 @.300
187.8 @.400
225.2 @.500
255 @ .600
282.7 @.700
291.7 @.750
#7 Intake
223.9 @.300
291.1 @.400
334.8 @.500
358.8 @.600
376 @.700
368.1 @.750
#7 Exhaust
148.6 @.300
179.9 @.400
212.1 @.500
256.1 @.600
277.5 @.700
288.2 @.750
There was a bigger difference between the "good"(#'s 1 & 5) and the "bad"(#'s 3 & 7) intake ports than I thought there would be. I have ported and tested mostly GM castings in the past and I know they vary a good bit but I expected aftermarket heads to be a little closer to equal. I'm sure I could tweak these ports and get them closer but I'm not sure I will. The exhaust ports had quite a bit of turbulance so I radiused the edges of the chambers below the exaust valve and radiused the edge of the valves themselves to try to reduce it. I haven't flowed them again to see if it helped or not. We tried a tulip exhast valve and it helped the turbulence but didn't make much difference on the actual flow numbers. If I decide to flow them again I'll repost the new numbers.
I had posted earlier that I would share the flow numbers on my heads that will be going on my 489. These are 320cc aluminum with a bowl blend and gasket match and blended chambers. I only flowed two cylinders #5 and #7 for a comparison. They were flowed on a Flow Lab 520 with a 4.310 bore fixture(all the way through). This flow bench locates the head with a head gasket just like it would be bolted on the block. I mention that because the flow bench I used to use was a Superflow 400 and it was not this way. You could move the head around on the fixture. It is also computer controlled and calibrated.
#5 Intake:
215.2 @.300
270 @.400
342.3 @.500
374.7 @.600
395.9 @.700
406.5 @.750
#5 Exhaust
157.8 @.300
187.8 @.400
225.2 @.500
255 @ .600
282.7 @.700
291.7 @.750
#7 Intake
223.9 @.300
291.1 @.400
334.8 @.500
358.8 @.600
376 @.700
368.1 @.750
#7 Exhaust
148.6 @.300
179.9 @.400
212.1 @.500
256.1 @.600
277.5 @.700
288.2 @.750
There was a bigger difference between the "good"(#'s 1 & 5) and the "bad"(#'s 3 & 7) intake ports than I thought there would be. I have ported and tested mostly GM castings in the past and I know they vary a good bit but I expected aftermarket heads to be a little closer to equal. I'm sure I could tweak these ports and get them closer but I'm not sure I will. The exhaust ports had quite a bit of turbulance so I radiused the edges of the chambers below the exaust valve and radiused the edge of the valves themselves to try to reduce it. I haven't flowed them again to see if it helped or not. We tried a tulip exhast valve and it helped the turbulence but didn't make much difference on the actual flow numbers. If I decide to flow them again I'll repost the new numbers.
