Pro comp bbc intake min CSA vs 454r min CSA and minimum to maximum differences
#11
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You don't compare port to port. You have to look at the whole port all the way to the valve. Port length needs to be considered as well. Size the port on the intake side to work with the head. Also, if you have a rectangle port you don't count the corners when calculating CSA. Air doesn't flow in the corners.
As far as CSA vs square inches, yes, in first post thats why i said for discussion lets just use square inches, if you calculate act cross sectional area the percentages dont change.
Biggest thing is i was surprised to find pinch points 1.28 wide and others at 1.500+ both having close to the same port height.
Last edited by articfriends; 11-30-2016 at 09:44 PM.
#12
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In a perfect world, the runners would taper. Biggest size at port entry, smallest at exit. If airspeed is going to be real high going into a sharp corner, the area just before may be enlarged a little to slow down the air at that point to help it make it around the corner....but, that is flowbench stuff. Just keep it in the back of your head.
And if going for a target CSA, remember you do have to measure it with your equipment accurately. Tough with just calipers, If there is a decent radius in the wall/roof/floor corners, it will have to be accounted for. If it is sharp, like Black Baja is mentioning, then it doesn't.
I wouldn't kill yourself on this intake project like with the MPI's as a carbed intake is not dealing with strong 2nd or 3rd harmonic tuned lengths like MPI (Tuned Port) intakes. Just a little work will go a long way.
And if going for a target CSA, remember you do have to measure it with your equipment accurately. Tough with just calipers, If there is a decent radius in the wall/roof/floor corners, it will have to be accounted for. If it is sharp, like Black Baja is mentioning, then it doesn't.
I wouldn't kill yourself on this intake project like with the MPI's as a carbed intake is not dealing with strong 2nd or 3rd harmonic tuned lengths like MPI (Tuned Port) intakes. Just a little work will go a long way.
#13
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Scott, im not going to grind on the 454r at all, its a borrowed intake, the difference between tightest to biggest minimum csa is so severe i would have to spend 50 hours straightening it out. The chinesium intake, much more uniform, did sll the modding to it im going.
As far as measuring the pinch points in the ports, aside from casting molds in each one , no its not super accurate using inside calipers but i do try to consistently do it and slso use a mean average, Smitty
As far as measuring the pinch points in the ports, aside from casting molds in each one , no its not super accurate using inside calipers but i do try to consistently do it and slso use a mean average, Smitty
#14
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We ran a carb version of that intake a few years ago in street/race car did for one of my sons, never did and dyno test, did do quite a bit of port matching and it was a oval using 781 heads, car ran faster than we thought it should. On the flip side, just got a victor jr for LS project I'm doing for my other son, casting was pretty damn rough on the edelbrock(did say USA) again did quite a bit of port clean up on this as well as using GMPP CNC ported heads. So bottom line is edelbrock seems to be the best intake out there at this point, still edgy on casting, the chinese stuff is really bad from what I have seen, but how much diff in power ????? thanks Smitty for all your testing/reporting
#16
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We ran a carb version of that intake a few years ago in street/race car did for one of my sons, never did and dyno test, did do quite a bit of port matching and it was a oval using 781 heads, car ran faster than we thought it should. On the flip side, just got a victor jr for LS project I'm doing for my other son, casting was pretty damn rough on the edelbrock(did say USA) again did quite a bit of port clean up on this as well as using GMPP CNC ported heads. So bottom line is edelbrock seems to be the best intake out there at this point, still edgy on casting, the chinese stuff is really bad from what I have seen, but how much diff in power ????? thanks Smitty for all your testing/reporting