Intake Manifold Porting Show ‘n Tell

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Re: Intake Manifold Porting Show ‘n Tell

Post by ChopperScott »

Any tips? :lol:
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Re: Intake Manifold Porting Show ‘n Tell

Post by ChopperScott »

SpeierRacingHeads wrote: Tue Nov 29, 2022 4:21 pm Dorton 300-110 I just finished up today. My favorite manifold.
Nice work! I've never had my hands on one of those, but it's always been on my radar.
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Re: Intake Manifold Porting Show ‘n Tell

Post by ChopperScott »

With regards concerning calculations and measurement of runner length, area, or airflow, how does one account for the chaos in the plenum?
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Re: Intake Manifold Porting Show ‘n Tell

Post by steve cowan »

rfoll wrote: Tue Nov 29, 2022 10:57 am I'm kind of late to the party but I have been using a different method for port match that only uses a gasket as a spacer. I think the articleport matching.jpg was from Vizard. There was mention of builing up with epoxy and I may need to do this. Any recommended brands?
I use Belzona 1111,it's expensive but I have had marine epoxy weep oil before.
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Re: Intake Manifold Porting Show ‘n Tell

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oops
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: Intake Manifold Porting Show ‘n Tell

Post by In-Tech »

ChopperScott wrote: Tue Nov 29, 2022 6:54 pm With regards concerning calculations and measurement of runner length, area, or airflow, how does one account for the chaos in the plenum?
The reality... is you can't. Change firing order and it changes what happens in the plenum.
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: Intake Manifold Porting Show ‘n Tell

Post by juuhanaa »

I would like to ask about him who designed this.

IMG-20220914-WA0007.jpg


-juhana
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Re: Intake Manifold Porting Show ‘n Tell

Post by Erland Cox »

juuhanaa wrote: Tue Nov 29, 2022 11:35 am
Erland Cox wrote: Tue Nov 29, 2022 6:56 am
juuhanaa wrote: Tue Nov 29, 2022 12:49 am

Good morning,

I dont get it. When the the calculated frequency match the given rpm, over scavenging doesnt have to be a problem and when taper is used to increase CSA, it changes the reflections on lower rpm to happen higher rpm.



-juhana
As soon as there is a discontinuity in area in the port the outgoing rarefaction pressure wave will reflect back to the cylinder.
If there is a larger area it will reflect a pressure wave.
So if we taper the head the ports reflections will help with filling the cylinder and on most engines this will prevent the cylinder
to draw a really deep vacuum.
That vacuum is what we need reflected at around BDC and forward to fill the cylinder with a late closing inlet valve.
So 3 things will happen, the vacuum pulled will be less, the returning pressure waves will be spent to early and they will also be weaker.
So where in the port the intake starts to taper up has a lot to do with at what rpm you want maximum hp.
I have never seen a Comp or PS head taper up before the intake manifold and they turn over 10000 rpm.
If you taper up to early the engine will not tolerate an as late closing intake valve as it could with the taper at the right place.

Erland
Yes, an engine tuned to third or fourth order harmonics and running lower piston speeds, we better of maintaining CSA to keep the airspeed up, and waves moving stronger back and forth in the system but.. Do you mean an engine with an induction tuned say at 6500rpm, 4000ft/min piston speed and much taper, that second order cannot arrive at the time of the IVC event?


When..
the "second order" = thing moves back and forth 3 times the tuned length.

Thing has a frequency, and if the system does not take into account the whole lenght, then the following harmonics should occur at much higher RPMs than a calculation using average inputs would show. In other words when we have taper, i don't think wave is reflected back from that area change inside a runner, but rather from the runner entry.

the "third order" = thing moves back and forth 5 times the tuned length

the "fourth order" = thing moves back and forth 7 times the tuned length

Thank you,



-juhana

The orders are during valve closed.
What I am referring to is from IVO to IVC.
Up to maximum piston velocity on the intake stroke is when the pressure for all the forthcoming waves are drawn.

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Re: Intake Manifold Porting Show ‘n Tell

Post by juuhanaa »

Erland Cox wrote: Wed Nov 30, 2022 4:35 am
juuhanaa wrote: Tue Nov 29, 2022 11:35 am
Erland Cox wrote: Tue Nov 29, 2022 6:56 am

As soon as there is a discontinuity in area in the port the outgoing rarefaction pressure wave will reflect back to the cylinder.
If there is a larger area it will reflect a pressure wave.
So if we taper the head the ports reflections will help with filling the cylinder and on most engines this will prevent the cylinder
to draw a really deep vacuum.
That vacuum is what we need reflected at around BDC and forward to fill the cylinder with a late closing inlet valve.
So 3 things will happen, the vacuum pulled will be less, the returning pressure waves will be spent to early and they will also be weaker.
So where in the port the intake starts to taper up has a lot to do with at what rpm you want maximum hp.
I have never seen a Comp or PS head taper up before the intake manifold and they turn over 10000 rpm.
If you taper up to early the engine will not tolerate an as late closing intake valve as it could with the taper at the right place.

Erland
Yes, an engine tuned to third or fourth order harmonics and running lower piston speeds, we better of maintaining CSA to keep the airspeed up, and waves moving stronger back and forth in the system but.. Do you mean an engine with an induction tuned say at 6500rpm, 4000ft/min piston speed and much taper, that second order cannot arrive at the time of the IVC event?


When..
the "second order" = thing moves back and forth 3 times the tuned length.

Thing has a frequency, and if the system does not take into account the whole lenght, then the following harmonics should occur at much higher RPMs than a calculation using average inputs would show. In other words when we have taper, i don't think wave is reflected back from that area change inside a runner, but rather from the runner entry.

the "third order" = thing moves back and forth 5 times the tuned length

the "fourth order" = thing moves back and forth 7 times the tuned length

Thank you,



-juhana

The orders are during valve closed.
What I am referring to is from IVO to IVC.
Up to maximum piston velocity on the intake stroke is when the pressure for all the forthcoming waves are drawn.

Erland
Thanks for your answer to my question, but the thing what i am also referring from IVO to IVC may not necessarily work like that throughout the RPM range, so i have to question your answer to my question about when does the wave arrive into the cylinder. Is also much possible that i dont understand the thing, but whatever op doesn't want us to have this discussion in his thread, so lets leave it here and continue elsewhere if it comes to that :) I appreciate for your time to reply, regards



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Re: Intake Manifold Porting Show ‘n Tell

Post by Erland Cox »

Look at the negative pressure drawn at 400 degrees.
This sets up the pressure the engine has to work with the next 650 something degrees.
Every time it changes sign means it har reflected at the other side of the runner.
A taper adds duration to the wave but takes amplitude from it.
The cylinder has drawn 0.55 bars of negative pressure at 400 degrees and that pressure + the pressure from the velocity
in the port is all we have to fill the cylinder before intake valve closing.
If a wave reaches a taper in the port during this draw it will get help to fill the cylinder.
That means that the negative pressure will not get as low as possible and that energy that could be used to fill the cylinder is wasted
when it does negative work instead of positive work. Timing is everything.
We must use that pressure cleverly at the right time to maximize intake filling from just before BDC to just before intake valve closing.
Reversing flow takes some time so cylinder pressure can be above intake port pressure at intake valve at intake valve closing.
This information belongs in the thread because it is the WHY to how things work.

Image

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Re: Intake Manifold Porting Show ‘n Tell

Post by pcnsd »

Erland Cox wrote: Wed Nov 30, 2022 10:56 am Look at the negative pressure drawn at 400 degrees.
This sets up the pressure the engine has to work with the next 650 something degrees.
Every time it changes sign means it har reflected at the other side of the runner.
A taper adds duration to the wave but takes amplitude from it.
The cylinder has drawn 0.55 bars of negative pressure at 400 degrees and that pressure + the pressure from the velocity
in the port is all we have to fill the cylinder before intake valve closing.
If a wave reaches a taper in the port during this draw it will get help to fill the cylinder.
That means that the negative pressure will not get as low as possible and that energy that could be used to fill the cylinder is wasted
when it does negative work instead of positive work. Timing is everything.
We must use that pressure cleverly at the right time to maximize intake filling from just before BDC to just before intake valve closing.
Reversing flow takes some time so cylinder pressure can be above intake port pressure at intake valve at intake valve closing.
This information belongs in the thread because it is the WHY to how things work.

Image

Erland
If I may summarize.
There are 3 pressure events occurring in Erland's provided graph. Two have their source in the intake cycle and one is sourced from the exhaust cycle.
Left to right, they are:
Primary ramming:
This is from a positive pressure event associated with intake valve closing on the previous cycle.
Secondary ramming:
This is from a negative pressure event associated with peak piston velocity on the same cycle.
Exhaust suction:
This is from a positive pressure event associated with the previous exhaust blow-down.
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Re: Intake Manifold Porting Show ‘n Tell

Post by SpeierRacingHeads »

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Re: Intake Manifold Porting Show ‘n Tell

Post by juuhanaa »

Erland Cox wrote: Wed Nov 30, 2022 10:56 am Look at the negative pressure drawn at 400 degrees.
This sets up the pressure the engine has to work with the next 650 something degrees.
Every time it changes sign means it har reflected at the other side of the runner.
A taper adds duration to the wave but takes amplitude from it.
The cylinder has drawn 0.55 bars of negative pressure at 400 degrees and that pressure + the pressure from the velocity
in the port is all we have to fill the cylinder before intake valve closing.
If a wave reaches a taper in the port during this draw it will get help to fill the cylinder.
That means that the negative pressure will not get as low as possible and that energy that could be used to fill the cylinder is wasted
when it does negative work instead of positive work. Timing is everything.
We must use that pressure cleverly at the right time to maximize intake filling from just before BDC to just before intake valve closing.
Reversing flow takes some time so cylinder pressure can be above intake port pressure at intake valve at intake valve closing.
This information belongs in the thread because it is the WHY to how things work.

Image

Erland
Say this picture is about 2:nd pressure wave ramming during valve closed/second order arrive into the cylinder at the time of the IVC event, so that the combined intake pressure trace reflects the frequency of the wave, and we see two orders working between IVO and IVC.
There is a good thing with constant taper and that is that it keeps the boundary layer thinner.
But there is a bad thing too.
The reflections för stuffing air into the engine are used before they are needed.
So 3 things will happen, the vacuum pulled will be less, the returning pressure waves will be spent to early and they will also be weaker.
What you said about taper contradicts the picture above, that a wave could enter the cylinder at the time of the IVC event. In other words cylinder ramming effect/changing velocity into static pressure AND wave tuning/pressure wave arriving into the cylinder could work hand in hand prior to IVC.



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Re: Intake Manifold Porting Show ‘n Tell

Post by ChopperScott »

Making progress…
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Re: Intake Manifold Porting Show ‘n Tell

Post by 1980RS »

ChopperScott wrote: Tue Nov 29, 2022 6:35 pm
SpeierRacingHeads wrote: Tue Nov 29, 2022 4:21 pm Dorton 300-110 I just finished up today. My favorite manifold.
Nice work! I've never had my hands on one of those, but it's always been on my radar.
I had one about 5 years ago but it was one for raised port runner heads so it didn't do me any good. I traded it for Vortec S/V which fit my needs at the time.
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