Question on port matching

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Here's John Kaase showing what actually happens in an engine rather than pretty computer generated ideas about flow.

Jon Kaase Uses Finger to Test Airflow

Does all that CFD stuff account for reversion and wet flow dynamics........Notice all that fuel on the walls? Where does that end up? Does it take into account the size of the fuel droplets that exit the booster of the carb? Can it calculate at what point which fraction transitions from a liquid droplet to a gas state?

Now what happens to all the fuel that ends up on the port floor of the manifold and then runs down into that large opening like a ported J head and then hits the ski jump as it now runs into all the air trying to get around the short turn. What does all this liquid fuel do to the fuel/gas and air already entrained? Does it help it or does it **** it up? Remember a liquid has mass so what's it gonna do? How much is there? Anyone really know? Does your flow bench tell you how an engine really works........

Last time I looked a Pro Stock engine doesn't have the large operating range requirements a street car engine has to get right. Nor do those guys have to deal with heavy end distillates that take a lot of heat to vaporize and burn.

I know of 1 engine where a change from an Airgap to a Performer was only worth a 10th loss in ET. Even funnier was that streetmaster manifold lost only 10hp to the Airgap @ 5600 RPM and that port miss match is HUGE by anyone's standard.
 
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Rat Bastid said:
Ive already said it. NONE. Never make the port in the manifold smaller than the head. Ever. I realize you have to change your thinking to get it, but it’s still the fact. Watch the Morgan videos. The last thing you want in any system is corners. The next worse thing is changes in section. And then a mismatch going with the flow.
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Sorry man, your just confusing me. I feel like your flipping back and forth. You said you said it before, I must have missed it. Now your saying none but earlier you were saying there has to be some because of the gain you say when there is with a larger port intake on a smaller head port.
 
Bewy said:
Rat Bastid.
None of the you tube videos in this thread support your contention that the opening in the intake man where it meets the head should be bigger & that it helps power because a smaller opening kills power, posts 28,40, 89. You mention fluid dynamics.
Water is a fluid. To duplicate the above scenario, where the port in the head is smaller & overhangs, get a garden hose & aim it at the corner of your house. See if you get smooth flow...
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I agree with you big time. RB has done nothing to show a larger intake port window is what needs/should/ought to be done in anyway shape or form and has wasted time by linking videos that do not support his words.

RB
The videos are very good. An understatement for sure.
But they have nothing to do with an intake manifolds port window meeting the head port window and the sizing of ether as they meet.

Im open minded to what can or could be better but I do need some type of proof that it is the right thing to do but also call out for what application.

You have done none of the above.

The only thing you have done is repeat yourself and your claim as well as insult anyone who does t agree with you and there lack of understanding on a matter that goes against all that I have read and seen. In fact you have moved away from the basic question of port matching into porting. Porting is not the topic.

You need to do a better job at convincing/teaching/explaining. The ball is in your court and I hope there is something to be learned.
 
All you have to do is look at manifold tests to see the restriction some manifolds present when used on a ported head.
A manifold must move the required air to take advantage of the higher CFM flowing head.
 
fishmens67 said:
All you have to do is look at manifold tests to see the restriction some manifolds present when used on a ported head.
A manifold must move the required air to take advantage of the higher CFM flowing head.
Click to expand...
That I can agree with. It seems to me that too few people flow their intakes, compared with people who know what their heads flow.
 
fishmens67 said:
All you have to do is look at manifold tests to see the restriction some manifolds present when used on a ported head.
A manifold must move the required air to take advantage of the higher CFM flowing head.
Click to expand...

Absolutely! Now -

How does the larger intake port to a smaller cylinder head port help and by how much or percentage is the intake port larger than the head port?

The ability of the intake or not, is not of or in question here. The question is, stated above.
 
I have wondered about how the valve event pulses effect the airflow of an intake . Alot more is going on in the tract than just 1 way airflow.
Its like running down an empty street vs running down a busy NY sidewalk .
 
Bewy said:
Rat Bastid.
None of the you tube videos in this thread support your contention that the opening in the intake man where it meets the head should be bigger & that it helps power because a smaller opening kills power, posts 28,40, 89. You mention fluid dynamics.
Water is a fluid. To duplicate the above scenario, where the port in the head is smaller & overhangs, get a garden hose & aim it at the corner of your house. See if you get smooth flow...
Click to expand...


Let me say it again. I know you have some mental issues that keep you from understanding simple English.

The first thing I said was don’t bother with the port match. If you don’t put the correct SHAPE back into the ports it’s a power loser.

I have never said to make the manifold bigger than the head. Get that through your thick skull. I said IF you have to have a mismatch at the head, make the manifold bigger than the head. I didn’t say that every intake manifold should be bigger than the head. This is why someone who has no idea of what they are doing shouldn’t be doing any port work. You can lose power very quickly with a bad port match.

Go back and watch the very first video I posted. It shows exactly what happens when you put a square edge down stream of flow. You get vortices. The other videos show what happens when you have a change in section. You get the same thing.

I know your limited experience and inability learn hamper you. This is another time when you need to go sit at the kiddy table and let the adults talk. You are clearly not capable of contributing anything of substance.
 
rumblefish360 said:
Absolutely! Now -

How does the larger intake port to a smaller cylinder head port help and by how much or percentage is the intake port larger than the head port?

The ability of the intake or not, is not of or in question here. The question is, stated above.
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Damn dude. Are you really having this much trouble understanding this? I’ve explained it more than once, more than one way.

I know in your mind you see the flow being hindered by the manifold being bigger, but it is exactly the opposite.

The flow will shear off the sharp edge and make a clean flow path. If you have a sharp edge on the down side of flow, it will cause vortices. Every time.

It’s nothing trick. It’s simple science. I’ve even laid out a simple way to test it on a flow bench.

And for the umpteenth time, I’m not saying to make the manifold bigger than the head. I’m saying IF you have to have a mismatch, make the manifold bigger than the head. This happens more often than one might think. Core shift is real. Sometimes you can’t unscrew core shift without welding. I that case, you make the manifold bigger than the head.

Leaving the port in the manifold smaller will lose power IN ALMOST EVERY CASE.

As you can see, some will come along with an outlier but the BEST scenario is to get the manifold and the head matched, without the manifold and head getting a bulge where the port match was done.

Maybe I need to make a video to explain it, although if watching the videos I’ve already posted doesn’t make it clear than nothing I can do will help.
 
Hysteric said:
Here's John Kaase showing what actually happens in an engine rather than pretty computer generated ideas about flow.

Jon Kaase Uses Finger to Test Airflow

Does all that CFD stuff account for reversion and wet flow dynamics........Notice all that fuel on the walls? Where does that end up? Does it take into account the size of the fuel droplets that exit the booster of the carb? Can it calculate at what point which fraction transitions from a liquid droplet to a gas state?

Now what happens to all the fuel that ends up on the port floor of the manifold and then runs down into that large opening like a ported J head and then hits the ski jump as it now runs into all the air trying to get around the short turn. What does all this liquid fuel do to the fuel/gas and air already entrained? Does it help it or does it **** it up? Remember a liquid has mass so what's it gonna do? How much is there? Anyone really know? Does your flow bench tell you how an engine really works........

Last time I looked a Pro Stock engine doesn't have the large operating range requirements a street car engine has to get right. Nor do those guys have to deal with heavy end distillates that take a lot of heat to vaporize and burn.

I know of 1 engine where a change from an Airgap to a Performer was only worth a 10th loss in ET. Even funnier was that streetmaster manifold lost only 10hp to the Airgap @ 5600 RPM and that port miss match is HUGE by anyone's standard.
Click to expand...

And this has to do with port matching how? That was the topic of the OP, and I clearly said don’t do it and then I laid out the reasons why.
 
rumblefish360 said:
Sorry man, your just confusing me. I feel like your flipping back and forth. You said you said it before, I must have missed it. Now your saying none but earlier you were saying there has to be some because of the gain you say when there is with a larger port intake on a smaller head port.
Click to expand...


Show me where I said to, on purpose make the manifold bigger than the head? This all got wonky because I told the OP to NOT port match his stuff. And this is exactly why.

It’s not what it really looks like. Changes in section are a big deal. In most cases, you want some taper in the port, from the carb flange to the valve seat. If you port match and don’t account for that and literally put a bulge in the port at the flange it will lose power. Every time.

Go back and look at the first video I posted. Watch what happens when the flow goes past the square edge. The flow tries to fill in behind that square edge and vortices happen. Increasing flow speed only makes it worse. That video makes it very clear.

One more time. IF and only IF you have to have a mismatch at the flange, make the manifold bigger than the head. Not the other way around.

Don’t get hung up on which will flow more air, which one will keep the fuel suspended in the air or anything else. It’s about not disrupting the flow AFTER the mismatch. The smaller intake port will cause unwanted turbulence AFTER the mismatch, the bigger intake port will not.
 
If my air gap intake ever shows up for the 416 shocker build it will be getting flowed and ported…I will post before after numbers
 
That would be cool. If you can, be sure to include how much it was off on all four walls and the before and after measurements of the port sizes if you can. Thanks.
 
It will be opened up to match my ported Promaxx heads…I’m interested to see if it will match what the heads flow
 
To bad you don’t have money to burn like the US government does! And time to kill like a retired guy with no hobbies. I’d ask ya to flow the intake and heads together with the intake OOTB, port matched and then opened up some more!

:rofl:
 
Rat Bastid said:
And this has to do with port matching how? That was the topic of the OP, and I clearly said don’t do it and then I laid out the reasons why.
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Airflow through a flow bench is not airflow through an engine.

What you think happens in an engine and what you think the air will do are 2 different things. A smaller intake manifold port (within reason) dampens reversion because the smaller port increases the velocity of the charge as it leaves the carb and through the manifold limiting the reversions ability to disrupt flow by continuing higher.

A slightly smaller intake manifold port allows the fuel on the walls to be re-entrained improving the mixture quality and strangely enough so does a smaller carb aka improved homogenization of the intake charge. Again what the flow bench tells you and what the engine sees are 2 different things. If the flow is both ways then the assumptions you make about it being only one way are clearly wrong.

Larry Meaux said that he had a hemi engine on his dyno that had a volumetric efficiency of 140%, only problem was it was losing 20% of that out the exhaust during the overlap period.......What you get and what you use are 2 different things.

Why didn't that streetmaster intake with its tiny port choke that 340 to death? The difference between it and the Airgap is huge yet it wasn't refelcted in the power at 5600 RPM if airflow is all that matters? 10 Hp difference........There's more to this than just raw airflow.
 
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rumblefish360 said:
To bad you don’t have money to burn like the US government does! And time to kill like a retired guy with no hobbies. I’d ask ya to flow the intake and heads together with the intake OOTB, port matched and then opened up some more!

:rofl:
Click to expand...
You would need to be the US government to afford an intake in Canada these days….it will probably cost $800…before porting
 
67autocross said:
It will be opened up to match my ported Promaxx heads…I’m interested to see if it will match what the heads flow
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Why would you do that ? lol
Something we've all done since the turn of the century.
I think the manifold will be pretty close to the head numbers.
 
fishmens67 said:
Why would you do that ? lol
Something we've all done since the turn of the century.
I think the manifold will be pretty close to the head numbers.
Click to expand...
I’m trying to get the heads flowing over 300 at 600 lift …. Not sure the Airgap can keep up without some work
 
Hysteric said:
Airflow through a flow bench is not airflow through an engine.

What you think happens in an engine and what you think the air will do are 2 different things. A smaller intake manifold port (within reason) dampens reversion because the smaller port increases the velocity of the charge as it leaves the carb and through the manifold limiting the reversions ability to disrupt flow by continuing higher.

A slightly smaller intake manifold port allows the fuel on the walls to be re-entrained improving the mixture quality and strangely enough so does a smaller carb aka improved homogenization of the intake charge. Again what the flow bench tells you and what the engine sees are 2 different things. If the flow is both ways then the assumptions you make about it being only one way are clearly wrong.

Larry Meaux said that he had a hemi engine on his dyno that had a volumetric efficiency of 140%, only problem was it was losing 20% of that out the exhaust during the overlap period.......What you get and what you use are 2 different things.

Why didn't that streetmaster intake with its tiny port choke that 340 to death? The difference between it and the Airgap is huge yet it wasn't refelcted in the power at 5600 RPM if airflow is all that matters? 10 Hp difference........There's more to this than just raw airflow.
Click to expand...

You know this, I know this, Larry Meaux knows this, I’m sure a slew of top notch people in the field know this. They pass this information down into the hands of the people so they now know this, why RB can not properly plain his position against this is beyond me.

I started to go through everything he said to make a huge long post but grew tired of talking with a wall and have decided to throw in the towel on this subject.

If anybody thinks that a larger intake port up against a smaller cylinder head port is better (LMMFAO&HARD!)
Please do so have at it and if you could, prove RB correct, please do so school me. I’ll only say if it is not on a MoPar engine, then I REALLY DGAF.

MoPar only her peoples!

Have a great one everybody!
 
After reading all these post, I'm not sure I have enough power to get to work today.... :(
 
Think of the port mismatch as you would a stepped header just different ends of where the combustion event takes place and then think about how you would design it to prevent reversion making its way back up the manifold runner.

Next time you look at the underside of your air cleaner lid look at that black stuff and think about how far that had to travel and against what to get there!
 
Personally ,I think this is a waste of bandwidth. :rolleyes:..
A matched port is the best, so why debate anything less.
 
The best way to explain this to people is to have them imagine the open bed of a pickup truck traveling down the freeway at 70 miles per hour watching that loan piece of paper bounce in circles near the cab...never blowing out.
If fact you'd also see other bits moving from near the tailgate toward the cab and joining in with the paper in its backwash tumble....oh like a stream..with a dead flow spot where it widens off to one side.

318's with 360 4 brl intakes....

Re suspension...or vorticies/back washing whirlpools.
 
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