[iron_goat]

Hey PY, just got my sm heads flowed by Paul Cater (thanks Paul!). 294/201 . In line with what Randy Repp has shared.
Numbers are at 28"

[Steve C.]

Note that max intake number was at 0.600" lift. Many are rated at 0.700" lift.


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[PontiacLars]

Cool, thanks. I have the same heads, but I have done some porting. Excited to try them on my 489 soon.

[25stevem]

What ID pipe was on the exh for these test?
The addition of a pipe will add 4 to 5% over the bare port flow numbers above .350” lift.

[Skip Fix]

Here are the CNC numbers- better but different Superflow benches.
0.200 Intake 139, Exhaust 115 , 83%

0.300 Intake 209 Exhaust 162, 77%

0.400 Intake 269 Exhaust 190, 70%

0.500 Intake 292-sounded like some turbulence, Exhaust 209, 71%

0.600 Intake 302 turbulence, Exhaust 222, 73%

0.700 Intake 304 turbulence,Exhaust 222, 73%

[Steve C.]

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.


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[iron_goat]

I'm not sure what the ID was. I'll find out.

Steve, I thought the squiggles were from making sure the pen was working lol, but I'll ask about that as well.

I'm picking up the heads on Monday so I'll get more info then. Paul was kind enough to reply to my message this morning, but I really don't want to bug him over the weekend.

[25stevem]

I would venture a guess and say yes to what’s being asked in post #6, because at .600” lift the level of air flow goes into regression.

This is a sure sign that the port velocity at the center of the short turn is too high.

On the other side of the coin it’s also why that port is producing 266 cfm @ .450”.

[Steve C.]

Opinion offered, and one that could generate interesting conversation and does not represent any endorsement....


"I don't get to excited if the port stalls or backs up. I have a number or heads out there that back up and are wicked fast and did on the dyno and in the car exactly what they were intended to do and make. I also lift the valve way into and past the "trouble spot". Now I rather it not be there but my data tells me that there is no magical voodoo stuff there. JMO"

John Marcella
Marcella Manifolds Inc.

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[Half-Inch Stud]

Helps to evaluate Turbulence with actual intake runner(s), and see what runner (Manifold ) calms the 4 Turbulent ports. other 4 port probably fine with most runners.

[Steve C.]

Related. Rocky Rotella measured the airflow capacity of Pontiac intake manifolds on his flow bench. He used a cylinder head to establish a baseline figure and re-measured airflow with an intake manifold connected to it.
Example, he found a stock manifold will flow around 88 to 88.5% of a bare head at 250 cfm, and modified (enlarged to full gasket size into the plenum), it will be closer to 91%.

During a discussion he stated... "Simply stating that a manifold flows XXX cfm is relatively meaningless without any indication of measure (lift range, pressure, etc). A more accurate indication of an intake's capability is its effect on peak cylinder head airflow, and that is best represented in a percentage between the two values."

OK, attaching an intake affects the peak cylinder head airflow. How would it affect turbulence, if any.
It would be of interest to take Skips cylinder heads with turbulence at known valve lifts and test them with its intended intake attached to see.


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[PAUL K]

Attaching a manifold to a turbulent port usually improves the situation on a flow bench. It slows down the air which helps it move past the part of the port causing the turbulence. However not a lot of benches flow at the same pressure drop a running engine sees.

[Steve C.]

Thanks Paul.

I guess that relates to the John Marcella statement in my post #9


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[blueghoast]

Originally Posted by Skip Fix

Here are the CNC numbers- better but different Superflow benches.
0.200 Intake 139, Exhaust 115 , 83%

0.300 Intake 209 Exhaust 162, 77%

0.400 Intake 269 Exhaust 190, 70%

0.500 Intake 292-sounded like some turbulence, Exhaust 209, 71%

0.600 Intake 302 turbulence, Exhaust 222, 73%

0.700 Intake 304 turbulence,Exhaust 222, 73%

So what happened, I mean they look so impressive.
Just a bad CNC program from the start. So disapointing.
Could they fixed in any way or not?


GT

[25stevem]

There are a few easy ways that turbulence/ flow regression can be resolved because there are many reasons this issue can be happening in the first place.

If bolting on a intake manifold which is one of the ways to fix it works, it’s not from purely slowing the air down ( which it could do ) but reducing the peak air flow volume which then in turn slows down the peak port air speed which is the root cause of the issue in the first place.


Having the right amount of port air speed ( FPS ) is just as important in terms of a motors average power band as is the peak air flow rate, in fact it can be argued that it’s even more important to many builds depending on the motors intended use.

In terms of your question Blueghoast of can it be fixed, the answer is yes.

In fact if all 4 intake ports would have been flow tested then then the results posted here it might have been found that only two of the 4 intake in one head have this issue.

This is because one of the reasons for this issue is the amount and direction of swirl generated.

In a parallel valve head as ours are two ports in each head swirl clockwise like water going down a drain and two want to fight this natural tendency and go the other way.

To truly flow balance all 8 ports this must be addressed.

To maybe help show what port air speed is like I offer this example.
If you have reached peak air flow in a test of a head done at a 28” depression then your looking at that air volume moving thru the port at over 230 mph.

As you might imagine from this keeping the need control of it can be a challenge, no less at choke off air speed which on average is .55 Mach or over 430 mph.

Hemi heads heads only swirl in one direction by the way.

[Skip Fix]

On mine a pretty basic valve job I think will improve it. I think some work on the short turn also. I think for $1500 they were hard to beat for an average street/strip motor.

As far as intake flow with a manifold- I did not test these with one. Back when I was doing NMCA Top Stock I flow tested a 73SD intake as they gave even factory aluminum intakes a 10 hp hip on factoring to see if it flowed as good. Weird deal on some fairly ported D ports to test it (I had RAIV on the car for class) the flow actually was up above head by itself at 0.300. Car ran the same even with weight reduction compared to an HO intake so a wash. And that sucker was heavy!

[Stan Weiss]

Originally Posted by 25stevem

There are a few easy ways that turbulence/ flow regression can be resolved because there are many reasons this issue can be happening in the first place.

If bolting on a intake manifold which is one of the ways to fix it works, it’s not from purely slowing the air down ( which it could do ) but reducing the peak air flow volume which then in turn slows down the peak port air speed which is the root cause of the issue in the first place.


Having the right amount of port air speed ( FPS ) is just as important in terms of a motors average power band as is the peak air flow rate, in fact it can be argued that it’s even more important to many builds depending on the motors intended use.

In terms of your question Blueghoast of can it be fixed, the answer is yes.

In fact if all 4 intake ports would have been flow tested then then the results posted here it might have been found that only two of the 4 intake in one head have this issue.

This is because one of the reasons for this issue is the amount and direction of swirl generated.

In a parallel valve head as ours are two ports in each head swirl clockwise like water going down a drain and two want to fight this natural tendency and go the other way.

To truly flow balance all 8 ports this must be addressed.

To maybe help show what port air speed is like I offer this example.
If you have reached peak air flow in a test of a head done at a 28” depression then your looking at that air volume moving thru the port at over 230 mph.

As you might imagine from this keeping the need control of it can be a challenge, no less at choke off air speed which on average is .55 Mach or over 430 mph.

Hemi heads heads only swirl in one direction by the way.

Steve,
Since you are talking about swirl, What would a good swirl curve look like for lets say Pontiac 96 head? Also does the swirl curve vary very much for different Pontiac head castings?

Just as a side. Have you ever seen a port where swirl changed direction?

Stan

[Skip Fix]

Since Pontiac had different chambers for 670 heads, 68-78(79 400s were cast in 78) D port heads, RAII, RAIV/HO/SD round port heads and RAV were different I would bet swirl is totally different in every one. And I bet when a lot of folks smooth the ridge between the laid back area to the rest of the chamber it also affects it.

Early E heads had a different "bathtub" chamber that the later E heads, and the Speedmasters. Probably a little different than KRE D ports, and of sure different than High Ports.

[Steve C.]

I had a set of 1969 #16 d-port heads that had welded-in modifications for swirl developed by Pete McCarthy many years ago. Apparently he only did a few chambers with it and was experimenting, some mention of it was featured in High Performance Pontiac magazine. I later sold them to Paul Knippen and today there is question if it was a big factor in their performance.

From early issues of High Performance Pontiac magazine about 32 years ago and Pete McCarthy's articles about head porting...

He talks about the most important element of port shape, and it's effect on the airflow direction into the chamber, commonly called "swirl". He stated if the qualities of high air volume are combined with high air velocity and rapid swirl, combustion efficiency can be enhanced.

BUT, it's not just about port shape only. He also noted how high-swirl technology can require that the shape of the combustion chamber to complement the port shape. A twisting, rotating fuel mixture will scatter quickly unless the chamber is shaped to accommodate the momentum of the air mass as it exits the port. He goes further to briefly discuss how he reshaped a combustion chamber roof to enhance combustion swirl efficiency.

And the article includes a picture how he reshaped the combustion chamber in the area around the intake valve to promote this swirl effect. Unfortunately I no longer have pictures of my chambers with the swirl modification.


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[Stan Weiss]

In this video Charles flow tests 2 different manifold on the same head (Chrysler W2). He also tests each manifold with a Wilson spacer. Which on one manifold at a few lift points cause reverse swirl but not on the other manifold.

https://www.youtube.com/watch?v=hXNbhSj_iP0

Stan