#21  
Old 03-26-2023, 05:58 PM
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Stan on test I have had done I have seen the dominant swirl pattern stop or even stop and then slightly reverse .
This was taking place right at the point when the air mass was forced to start flowing the contours of the port .

It was so brief that it could only be seen when testing in .050” increments.

I don’t think much swirl is needed or wanted once a motor is running above 5000 rpm, especially if the port velocity is near to being too much.

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Old 03-26-2023, 09:41 PM
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Quote:
Originally Posted by Steve C. View Post
Skips indication of turbulence in the 0.500"-0.600" range brings to mind a question. Do the squiggly lines on the left side of the flow sheet posted by the OP represent turbulence ? Same general lift range as Skip.


.
I think that is correct. He scribbled those lines next to the lift numbers, plus the wave gets bigger at the bottom as the lift went up. The flow numbers reflect it also.

Maybe it had some core shift moving the short turn into the bowl more creating some turbulence earlier than normal. It had good low and mid lift flow numbers. With stock sized ports, I doubt that extra turbulence will effect much of anything, it did pretty well.

  #23  
Old 03-27-2023, 11:51 AM
iron_goat iron_goat is offline
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Paul confirmed the squiggly lines represent turbulence - shallow and big representing less and more. At the big line turbulence was enough to where he couldn't keep the manometer at 28".

He indicated the casting is clean with no porosity. Intake cleanup can put the flow at 300 and a good valve job on the exhaust can likely raise the numbers to 220. Exhaust seats weren't cut deep enough which resulted in heights about .050" shorter than the intake. I feel like I've read similar measurements from others, I just don't recall where.

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Old 03-27-2023, 12:59 PM
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Those lines indicate how the fluid in the test pressure Manometer start to bounce up and down where you have the test pressure set.
It starts out in a given lift point range with just a shallow amount of movement and can get up to more then a full inch of test pressure bounce.

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Old 04-02-2023, 12:00 PM
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The CNC version only picked up ~10cfm. I was under the impression that 300 cfm for E-heads was simply cleaning up the port with sand paper rolls and voila 300 cfm. Hardly an improvement to call it a CNC port.

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Old 04-02-2023, 12:12 PM
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Originally Posted by ponjohn View Post
The CNC version only picked up ~10cfm. I was under the impression that 300 cfm for E-heads was simply cleaning up the port with sand paper rolls and voila 300 cfm. Hardly an improvement to call it a CNC port.
Remember that CNC means nothing more than a machine did it and not a person. It tells you nothing about what the machine did.

Stan

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Old 04-03-2023, 08:58 PM
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Remember that CNC means nothing more than a machine did it and not a person. It tells you nothing about what the machine did.

Stan
I completely understand that. BUT what I am saying is 300 cfm can be achieved with a gasket match, clean up and good valve job...so why bother?

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Old 04-04-2023, 07:13 AM
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I completely understand that. BUT what I am saying is 300 cfm can be achieved with a gasket match, clean up and good valve job...so why bother?
You have to remember when the CNC heads were ordered there were no flow numbers available, so no one knew what they would be getting. The CNC on the exhaust side is much better then the intake side.

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Old 04-04-2023, 07:57 PM
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Flow numbers can sometimes be misleading by themselves. Has anyone measured the port volume for ether the as cast or CNC ported heads?

Stan

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