Question on port matching

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flyfish said:
I will add, all 3 of my Edelbrock intakes (RPM, RPM Air-Gap, Victor) had MAJOR core shift....I had to go ham with the grinder to get the ports in the same ball park as the heads. Just my 2 cents.

Edit: I really like how the Edelbrock intakes perform, but the QC is lacking.
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FWIW....I got a Victor manifold from a member here that had not been touched. I bolted it up to my Eddie RPM heads on my 408 and was shocked to see how perfect the intake runners matched the head port openings. The Victor is large enough and straight enough that you can look down each port with a flashlight. I was ready to get out the grinder but pleasantly found they didn't need touched. I probably got lucky with the parts I got. (But make no mistake, that good fortune was more than balanced out by other challenges elsewhere in the car's build!!)
 
I would say that smoothing out the casting flash and any very rough edges inside the port is always a good thing.
Gasket matching on an engine that rarely sees over 4000 R.P.M. will probably give you little to no gains, but it wouldn't hurt especially if you plan to upgrade the cam etc. in the future and rev it more.....
 
rumblefish360 said:
As long as the intake is smaller than the head port, it’s OK. Not great, but the reverse is really bad.
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Actually you never want the intake smaller than the head. They should be the same size but if you have to have a mismatch, the port in the intake needs to be bigger than the head, not the other way around. A smaller port in the manifold is a sure fire power killer.
 
I liked that episode...... and was pretty surprised at the “port match” results.

On a lower HP combo, the differences would likely be less.
 
I like that episode as well. Two surprises for me. The port match results were impressive and the full on high dollar Wilson porting was impressive.
 
Rat Bastid said:
Hmmmm. I’ll have to go look. I subscribe. I may have missed an episode.
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Title on the TV was " is intake manifold port matching worth it?" Don't know the episode #. Three identical intakes. One as cast, one port matched, one Wilson ported. Plus a spacer test at the end.
 
A similar episode, but with heads would be interesting.

Unported castings right ootb, “prepped”(valve job and bowls), fully ported.

The fully ported version should be cnc...... that way it represents something anyone could aquire.
I’d prefer to see it done on something like a 500” build capable of over 600hp with the ported version.
I’d also use Stealth heads since on the flow bench at least, there is a notable difference in flow between those 3 stages.

Then....... to take it one step further....... since the intake swap on a BBM is so easy....... try an ootb and reworked manifold on each set of heads.
 
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Demonx2 said:
FWIW....I got a Victor manifold from a member here that had not been touched. I bolted it up to my Eddie RPM heads on my 408 and was shocked to see how perfect the intake runners matched the head port openings. The Victor is large enough and straight enough that you can look down each port with a flashlight. I was ready to get out the grinder but pleasantly found they didn't need touched. I probably got lucky with the parts I got. (But make no mistake, that good fortune was more than balanced out by other challenges elsewhere in the car's build!!)
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I have a NOS W2 Victor that I gasket matched to my heads only to find it had core shift . The drivers side manifold posts are about 1/16" out of alignment with the head ports. Now I have to fill and report them .

This is why you should port match instead of gasket match .

My Pro Dominator Tunnel Ram is spot on !
 
PRH said:
A similar episode, but with heads would be interesting.

Unported castings right ootb, “prepped”(valve job and bowls), fully ported.

The fully ported version should be cnc...... that way it represents something anyone could aquire.
I’d prefer to see it done on something like a 500” build capable of over 600hp with the ported version.
I’d also use Stealth heads since on the flow bench at least, there is a notable difference in flow between those 3 stages.

Then....... to take it one step further....... since the intake swap on a BBM is so easy....... try an ootb and reworked manifold on each set of heads.
Click to expand...


They did an episode with small block Mopar Edelbrock heads . They ran them stock then Dulcich moved the pushrod and ported them . Then they dynoed it again . BIG DIFFERENCE!
 
So is having the intake charge crash into the cylinder head. A lot of our point of views is dependent on how bad the alignment is and how much smaller the intake is to the heads.
If my intake port is smaller, I not meaning a lot, just a little.
Rat Bastid said:
Actually you never want the intake smaller than the head. They should be the same size but if you have to have a mismatch, the port in the intake needs to be bigger than the head, not the other way around. A smaller port in the manifold is a sure fire power killer.
Click to expand...
 
PRH said:
A similar episode, but with heads would be interesting.

Unported castings right ootb, “prepped”(valve job and bowls), fully ported.

The fully ported version should be cnc...... that way it represents something anyone could aquire.
I’d prefer to see it done on something like a 500” build capable of over 600hp with the ported version.
I’d also use Stealth heads since on the flow bench at least, there is a notable difference in flow between those 3 stages.

Then....... to take it one step further....... since the intake swap on a BBM is so easy....... try an ootb and reworked manifold on each set of heads.
Click to expand...
Aren't stealths available cnc ported, the Super stealths? I think the promaxx are available cnc'ed too. You would only need two pair of heads, but might need to fix the valve job on both.
 
rumblefish360 said:
So is having the intake charge crash into the cylinder head. A lot of our point of views is dependent on how bad the alignment is and how much smaller the intake is to the heads.
If my intake port is smaller, I not meaning a lot, just a little.
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A sharp edge in the direction of flow is a much better scenario than having a transition to a sharp edge the other way. If the sharp edge is on the head, the air will simply shear off of it and follow the port wall.

If you have the intake smaller where it meets the head, you impose a big low pressure area right there and the air tries to fill in that gap. When it does, it causes eddies and such that kill flow. There are dozens of YouTube videos showing this happening. You never want the intake port smaller than the head.
 
33IMP said:
Aren't stealths available cnc ported, the Super stealths? I think the promaxx are available cnc'ed too. You would only need two pair of heads, but might need to fix the valve job on both.
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440source posted last year that they sent 100’s of heads to a northern head porter to have cnc’d like in the past and bad things occurred. Not sure how the deal turned out yet.
 
Rat Bastid said:
A sharp edge in the direction of flow is a much better scenario than having a transition to a sharp edge the other way. If the sharp edge is on the head, the air will simply shear off of it and follow the port wall.

If you have the intake smaller where it meets the head, you impose a big low pressure area right there and the air tries to fill in that gap. When it does, it causes eddies and such that kill flow. There are dozens of YouTube videos showing this happening. You never want the intake port smaller than the head.
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That seems contrary to logic but it may be true. The other problem with having a smaller intake port is the air could stall in the head port.
 
mbaird said:
That seems contrary to logic but it may be true. The other problem with having a smaller intake port is the air could stall in the head port.
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It is true. Based on science of fluid dynamics. You can find many videos on YouTube that show this very thing.
 
I gasket match my heads to the gasket, then port match the intake on anything I build. After the heads are on the engine, I use a contact cement like Gasgachinch to stick the gasket to the head. Just a couple small spots is all it takes. Then I install the intake, the felpro gaskets I use on factory type heads stick up past the top of the intake, so I scribe a line along the top of the intake flange. Then remove the intake and gaskets, keeping the gaskets on their respective sides I bolt them to the intake making sure the scribed lines are in the correct position. After that I use a sharp scribe to mark the blued intake flange and go to grinding after the gaskets are removed.

This and $1.75 will buy you a cup of coffee in some places.
 
Rat Bastid said:
A sharp edge in the direction of flow is a much better scenario than having a transition to a sharp edge the other way. If the sharp edge is on the head, the air will simply shear off of it and follow the port wall.

If you have the intake smaller where it meets the head, you impose a big low pressure area right there and the air tries to fill in that gap. When it does, it causes eddies and such that kill flow. There are dozens of YouTube videos showing this happening. You never want the intake port smaller than the head.
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At what size port mismatch? I understand what your saying. Not arguing it ether. Just wondering at or how much of a mismatch your speaking of. Because earlier you said that a smaller intake runner is bad for power as in choking. While this is a non arguable truth, at what level or size of mismatch. IMO, the way I read it was your saying it’s going to be huge. But what’s the port window differences?

I can’t see a lot with, OH, let’s just call it .010. But I can see a issue with .100. Nevermind some wild intakes I’ve had to mess with that have measure a straight up 1/4 and better! I figure that’s got to be massive even on a low power build. Probably catastrophic on something your looking to make some serious power with.

And that’s another thing. At what power level are you talking about?

Rat Bastid said:
It is true. Based on science of fluid dynamics. You can find many videos on YouTube that show this very thing.
Click to expand...
Would you mind posting up one or two?
That would be cool to see what’s going on.
I can’t see a minor mismatch being a big issue on low powered builds. I also don’t see the “Eddie’s” in my head unless the mismatch is substantial. Though I don’t know what that particular measurement would be. I can also see that as a percentage rather than a clear cut measurement. A .010 mismatch (ether way) is not the same obstruction between a 318 head and a fully ported max wedge head.

When the OP asked this question, there was no build stated (he’s miles away from a build) no parameters, no displacement given, no goal, just a general question.
 
rumblefish360 said:
At what size port mismatch? I understand what your saying. Not arguing it ether. Just wondering at or how much of a mismatch your speaking of. Because earlier you said that a smaller intake runner is bad for power as in choking. While this is a non arguable truth, at what level or size of mismatch. IMO, the way I read it was your saying it’s going to be huge. But what’s the port window differences?

I can’t see a lot with, OH, let’s just call it .010. But I can see a issue with .100. Nevermind some wild intakes I’ve had to mess with that have measure a straight up 1/4 and better! I figure that’s got to be massive even on a low power build. Probably catastrophic on something your looking to make some serious power with.

And that’s another thing. At what power level are you talking about?


Would you mind posting up one or two?
That would be cool to see what’s going on.
I can’t see a minor mismatch being a big issue on low powered builds. I also don’t see the “Eddie’s” in my head unless the mismatch is substantial. Though I don’t know what that particular measurement would be. I can also see that as a percentage rather than a clear cut measurement. A .010 mismatch (ether way) is not the same obstruction between a 318 head and a fully ported max wedge head.

When the OP asked this question, there was no build stated (he’s miles away from a build) no parameters, no displacement given, no goal, just a general question.
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I think I can find one really good video. It’s about turbulence but it’s a really good one. Then I’ll see what else I can find. Some of the best were from the 1950’s and 60’s. Those are a bit tougher to find.

The mismatch doesn’t have to be much if the manifold is smaller. Any change in cross section causes pressure changes in the port. And the Eddie’s that form are quite surprising. Let me see what I can find.
 
Here is one video. It’s a PITA to do this on my phone so I hope it works.



I’ll post a couple more when I get home.
 
There is a Youtube video on port flow using thermal imaging or some type of dye that illustrates what is happening in the ports. Its pretty surprising !
It shows how fuel can get sheared from the flow in certain situations.
 
Thanks. But! Even though it was a really good video, I have one point of disagreement with the videographer. The floor doesn’t move or provide energy. Resistance, yes! Resistance! I see where that can be seen or likened to movement.

Should you find a video within the cylinder head showing your side, I’d be much more in minded to flip my position on which is better. Shy of a back to back dyno test with a listing of port mismatch amounts going both ways….. I still think the fuel & air charge crashing into the cylinder head is worse.

It also makes me wonder, not only what differences would show up on a .010, .100, 1/4”, but also at different power levels and engine sizes. On both points of view of course! Ow my mind is wondering a bit deeper and it just makes me want to experiment. Now if I only had a dyno!
 
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