AUTOMAN
XS650 Addict
The "dead" area in the corners are what steer the airflow around the short side.
Do not fill.
cliff
Do not fill.
cliff
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Wannabriden's D Port Re-Port
- Thread starter BluzPlayer
- Start date
The thing to remember is a flow bench is nothing more than a tuning tool that can never duplicate a real engine running dynamics. To some extent, dead
areas like in the corners or floor can become active at higher RPMs preventing port choking and allowing more HP fine-tuning at higher RPMs. I know what the D port can do and it's a very efficient design that flows big but it's not for everyone and that's OK.
AUTOMAN
XS650 Addict
BTW how many feet per minute are you showing with the pitot tube?
cliff
cliff
AUTOMAN
XS650 Addict
As for pitot tubes.. I use them and these special valves to map velocity around the seat at various lifts.
example 6.4L
example 6.4L
Hello Cliff..
Welcome to the thread.
It is always great to have others with similar interest involved and sharing different knowledge/techniques etc.
The purpose of this thread is for discovery. It is for me to learn from others and for others to learn as well.
To create discussion and share thoughts and ideas to help expand our abilities.
But if it can't be tested and proven repeatedly I place no value to it. I have absolutely no dog in this hunt.
I have no reason to "protect" an idea or concept, making me available and open to exploring any and all.
The numbers, the entire variety of tests; they are what they are. My number one objective is to be repeatably accurate.
I've had to accept errors of my own along the journey. Again the numbers are what they are whether I like them or not.
Having said all that I couldn't disagree with this statement more. I mean no offense, and I love having civil debate on different ideas, philosophies, concepts. It is a way of learning new ideas or understanding. We don't know what we don;t know....
However I must say that tI have seen absolutely no testing that will validate that statement. In fact it is just the oppposite. Testing proves that inactive areas are detrimental to any port design.The greater the inactivity the less efficient the port design. Statements like this are often repeated as gospel when they are in fact complete fallacies. Usually they are used when someone is so attached to an idea or concept that they willfully overlook what are known deficiencies. Not saying that is your reasoning. I will say that refusing to recognize a deficiency prevents progress from being made by addressing the issue. Many people repeat these idioms because it was something they heard or read. But in this instance it went one step further; instead of recognizing the defect for what it is; an attempt is made to declare that the defect is in fact a positive that aids the port in moving the fuel mixture through the port.
And so it goes....
An ACTIVE port is one of the golden rules of porting.
The reason is very simple even beyond attempting to maximize efficiency. This is one of the very most basic tenents of porting 101 for beginners.
I covered this before, however I realize not everyone reads the entire thread so I will repeat it here.
The following is perhaps the best explanation I have come across:
Think of it this way; on a windy fall day, where are the leaves? Up in the AIR! What happens when the wind stops?
The leave drop to the ground. Have you noticed where the leaves collect around your house? It is where the wind DOESN'T blow. The stagnant low velocity areas. The leaves represent the fuel and the wind is the air in the port.
Fuel collects in thos dead areas where the flowballs indicate nothing is happening. It has dropped out.
An IDEAL port is one, where in any position, at any point, the flowball will hurt the flow. This indicates that all surfaces have energy or are active. That is the goal.
As for helping the air make the turn...
I have a special valve I use to measure vacuum off the top of the vavle to map how air is moving across the valve. It can be clocked into any position.
The D Port is no more efficient than any of the active ports I have tested with regards to the air making the short side turn. It is less so than some, especially at low lifts which I found surprising. Of course the smoke testing I have done indicates the same as one can see the air moving past the short turn across the valve to the long side. Not that it is a particularly bad thing at the lowest lifts (.05,.10) when something called windowing can be made useful with a good scavenging exhaust and adequate overlap. These tests take time to perform and they are repeated for accuracy. I do them for a purpose. The least important information about a ported head is the CFM numbers.
I will demonstrate the theory in the below video. Hopefully the video will put an end to that line of thinking, and help bring some clarity.
I don't know how to make it any clearer. There is always give and take with any port design but we should always represent it for what it is.
We can only do the best we can. That is why we test at the deepest depression possible. There are several head/motor builders that have 40" of depression and more.Why so much? Because issues that don't reveal themselves at lower pressures are brought to light. That is why I built my bench to run 25"-28" of depression depending on lift. A Superflow 600 (considered the industry standard) only flows to 25" and is converted to 28"
You are familiar with this as your head was flowed on a 16" bench which flowed your head at the highest lift at 12". Then your numbers adjusted to 28".
At least as seen in the video you provided in your thread. If I misconstrued what I saw I will stand corrected.
Air that makes a turn at 10", 12" 16" can easily break loose at 28" creating turbulence and inefficiencies not seen at the lower depressions.
Air at 28" can break loose at 40". We can only do the best we can with what we have. However we should do so with an understanding of the limitations.
Since I have tested this as well I can also say that "corrected" CFM is not always equal to the CFM tested at the actual pressure. The greater the difference in depression one has to correct for the more variance. A value of 80 CFM @ 28" adjusted from 10" of pressure is not the same as 80 CFM tested at 28".
None of this is opinion, It is reality that these things are well understood as standards within the world of porting.
My studies like many others show that issues and defects do not "correct" themselves as the pressures increase.
They do just the opposite. As the video above demontrates, there is simply no way to validate having those dead spots within the port.
Doesn't mean the port can't be effective. I believe that the head built for Chris "Spungle" was a long rod engine with a high lift cam. (.440?)
It lives up high, where the D Port is most effective. That is of course much different than the motor this head is designed for. Heads should be ported engine specific and not one size fits all. There are various parameters that guide a porter toward "targets" to ensure an efficient port for any particular motor. It is also VERY important to keep in mind that the D Port I tested was NOT a head you created but one inspired by and copied from your work. There is no question the head I tested was not up to your standards and it is NOT representative of your work.
More coming......
Welcome to the thread.
It is always great to have others with similar interest involved and sharing different knowledge/techniques etc.
The purpose of this thread is for discovery. It is for me to learn from others and for others to learn as well.
To create discussion and share thoughts and ideas to help expand our abilities.
But if it can't be tested and proven repeatedly I place no value to it. I have absolutely no dog in this hunt.
I have no reason to "protect" an idea or concept, making me available and open to exploring any and all.
The numbers, the entire variety of tests; they are what they are. My number one objective is to be repeatably accurate.
I've had to accept errors of my own along the journey. Again the numbers are what they are whether I like them or not.
Having said all that I couldn't disagree with this statement more. I mean no offense, and I love having civil debate on different ideas, philosophies, concepts. It is a way of learning new ideas or understanding. We don't know what we don;t know....
However I must say that tI have seen absolutely no testing that will validate that statement. In fact it is just the oppposite. Testing proves that inactive areas are detrimental to any port design.The greater the inactivity the less efficient the port design. Statements like this are often repeated as gospel when they are in fact complete fallacies. Usually they are used when someone is so attached to an idea or concept that they willfully overlook what are known deficiencies. Not saying that is your reasoning. I will say that refusing to recognize a deficiency prevents progress from being made by addressing the issue. Many people repeat these idioms because it was something they heard or read. But in this instance it went one step further; instead of recognizing the defect for what it is; an attempt is made to declare that the defect is in fact a positive that aids the port in moving the fuel mixture through the port.
And so it goes....
An ACTIVE port is one of the golden rules of porting.
The reason is very simple even beyond attempting to maximize efficiency. This is one of the very most basic tenents of porting 101 for beginners.
I covered this before, however I realize not everyone reads the entire thread so I will repeat it here.
The following is perhaps the best explanation I have come across:
Think of it this way; on a windy fall day, where are the leaves? Up in the AIR! What happens when the wind stops?
The leave drop to the ground. Have you noticed where the leaves collect around your house? It is where the wind DOESN'T blow. The stagnant low velocity areas. The leaves represent the fuel and the wind is the air in the port.
Fuel collects in thos dead areas where the flowballs indicate nothing is happening. It has dropped out.
An IDEAL port is one, where in any position, at any point, the flowball will hurt the flow. This indicates that all surfaces have energy or are active. That is the goal.
As for helping the air make the turn...
I have a special valve I use to measure vacuum off the top of the vavle to map how air is moving across the valve. It can be clocked into any position.
The D Port is no more efficient than any of the active ports I have tested with regards to the air making the short side turn. It is less so than some, especially at low lifts which I found surprising. Of course the smoke testing I have done indicates the same as one can see the air moving past the short turn across the valve to the long side. Not that it is a particularly bad thing at the lowest lifts (.05,.10) when something called windowing can be made useful with a good scavenging exhaust and adequate overlap. These tests take time to perform and they are repeated for accuracy. I do them for a purpose. The least important information about a ported head is the CFM numbers.
I will demonstrate the theory in the below video. Hopefully the video will put an end to that line of thinking, and help bring some clarity.
I don't know how to make it any clearer. There is always give and take with any port design but we should always represent it for what it is.
You are absolutely correct here is no way to absolutely represent the pressures and velocities in a running motor.
We can only do the best we can. That is why we test at the deepest depression possible. There are several head/motor builders that have 40" of depression and more.Why so much? Because issues that don't reveal themselves at lower pressures are brought to light. That is why I built my bench to run 25"-28" of depression depending on lift. A Superflow 600 (considered the industry standard) only flows to 25" and is converted to 28"
You are familiar with this as your head was flowed on a 16" bench which flowed your head at the highest lift at 12". Then your numbers adjusted to 28".
At least as seen in the video you provided in your thread. If I misconstrued what I saw I will stand corrected.
Air that makes a turn at 10", 12" 16" can easily break loose at 28" creating turbulence and inefficiencies not seen at the lower depressions.
Air at 28" can break loose at 40". We can only do the best we can with what we have. However we should do so with an understanding of the limitations.
Since I have tested this as well I can also say that "corrected" CFM is not always equal to the CFM tested at the actual pressure. The greater the difference in depression one has to correct for the more variance. A value of 80 CFM @ 28" adjusted from 10" of pressure is not the same as 80 CFM tested at 28".
None of this is opinion, It is reality that these things are well understood as standards within the world of porting.
That statement is pure conjecture since there is absolutely no way to test it.
My studies like many others show that issues and defects do not "correct" themselves as the pressures increase.
They do just the opposite. As the video above demontrates, there is simply no way to validate having those dead spots within the port.
Doesn't mean the port can't be effective. I believe that the head built for Chris "Spungle" was a long rod engine with a high lift cam. (.440?)
It lives up high, where the D Port is most effective. That is of course much different than the motor this head is designed for. Heads should be ported engine specific and not one size fits all. There are various parameters that guide a porter toward "targets" to ensure an efficient port for any particular motor. It is also VERY important to keep in mind that the D Port I tested was NOT a head you created but one inspired by and copied from your work. There is no question the head I tested was not up to your standards and it is NOT representative of your work.
More coming......
I have a few charts posted above.
The pitot tube has yet to be calibrated so the actual FPM would be useless at the moment.
That does not prevent me from using it to find flow patterns and compare the fastest parts of the port to the slowest.
So it is still very beneficial for mapping.
I'd be interested in how you went about calibrating your Pitot tube as well.
I have a few procedures I will be exploring and hopefully be able to check test the results.
The Pitot is one of my key tools
VERRRRRYYYY Trick Valve.
Make me jealous.
My valve is much simpler and works similarly.
There is a picture of it somewhere in the thread.
My valve feels the depression from the top of the valve as the air moves over it as opposed to the edge.
It is not calibrated and only used for comparison puposes so it performs quite well.
It is very consistent which is the critical aspect.
Hudriwudri
XS650 Addict
@Jack
If you talk about Jim's thread, yours truly was also posting there as i ported some years ago about a very successful DBD 34 head I worked on with a, then unknown to me, very similar port shape and excellent flow numbers despite high gas velocity and excellent volumetric efficiency and throttle response.
I guess at the end it boils, imho, down to the knowledge pool of guys like Kenny Augustine, Axtell and Jerry Branch as these guys discovered those findings already decades ago.
The XR 750 port modification as on the Commando can unfortunately not be transfered 1:1 to the XS as the Norton has to begin with a steeper valve angle among maybe some other details, thus different flow patterns around the SSR as well as around the valve.
@BluzPlayer
Hefty compliments for all your effort.
I'm sorry that I did not participate in your thread as I'm fully taken by family, life of Work and the heads I have here for completion.
Regarding the so called dead areas of the corners. As said I'm very busy lately with family etc, thus haven't read through your numbers but along the SSR edge, depending on port Type/inclination you will always find at times a big velocity gradient.
I would recommend, in case not done yet, to take the flow ball to the apex/middle of the SSR (slide it from below the guide boss forward to the turn) and see if and how numbers on the SSR change.
Kind regards Christian
PS: regarding the floor raising statement, very good idea,but beware of the oil gallery in case you go further up with the intake port for a better SSR shape,but I guess you knew that already!
If you talk about Jim's thread, yours truly was also posting there as i ported some years ago about a very successful DBD 34 head I worked on with a, then unknown to me, very similar port shape and excellent flow numbers despite high gas velocity and excellent volumetric efficiency and throttle response.
I guess at the end it boils, imho, down to the knowledge pool of guys like Kenny Augustine, Axtell and Jerry Branch as these guys discovered those findings already decades ago.
The XR 750 port modification as on the Commando can unfortunately not be transfered 1:1 to the XS as the Norton has to begin with a steeper valve angle among maybe some other details, thus different flow patterns around the SSR as well as around the valve.
@BluzPlayer
Hefty compliments for all your effort.
I'm sorry that I did not participate in your thread as I'm fully taken by family, life of Work and the heads I have here for completion.
Regarding the so called dead areas of the corners. As said I'm very busy lately with family etc, thus haven't read through your numbers but along the SSR edge, depending on port Type/inclination you will always find at times a big velocity gradient.
I would recommend, in case not done yet, to take the flow ball to the apex/middle of the SSR (slide it from below the guide boss forward to the turn) and see if and how numbers on the SSR change.
Kind regards Christian
PS: regarding the floor raising statement, very good idea,but beware of the oil gallery in case you go further up with the intake port for a better SSR shape,but I guess you knew that already!
Last edited:
Yes the head was flowed on a SF 110 , then flowed it on his friend's SF 600 to validate my friend's 110 cross-over formulation numbers and you also validated my numbers on your DIY flow bench. As for the D port being a high RPM port, you need to go back and check the gains achieved from 100 to 480, you don't achieve those sorts of gains with big ports where velocity is lost or obstructions in the mainstream to boost CFM. The D port was built for the street to obtain maximum CFM at low lifts using small lift cams or high lifts despite the rod ratio being a short or long period. Due to the inherited casting and port issues of the XS, obtaining CFM gains has always been and will be the # 1 priority if you want to build power. The notion that the D port is not efficient or most effective at a high RPM is pure nonsense, I've had my idea tested on an actual motor and the result was postive.As for CFM values at 10" vs 28" who cares, the XS isn't going shatter the world Guinness Book of parallel twin HP? What I look for is whether or not I made or lost gains. No Chris's cam was Shell #1 with a 533 bottom end.
Hi Christian and yes I saw you posted on that subject over at Access Norton and after researching what it would take to convert this Harley port,l lost interest.
Hudriwudri
XS650 Addict
@Jack
If you want to indulge yourself more into the history of the D-port, actually it was afaik a makeshift crutch in order to get the flow around the bend of the supercharger inlet of the P51 as it was pretty space restricted.
In case interested go on the Nasa homepage and look for the NACA papers, somewhere in that paper the lowering of the corner velocity together with the raising of overall volumeflow gets discussed
At the end it boils down to fluid mechanics.
All the best and kind regards
Christian
PS: as said I'm also inclined to think that there are unfortunately quite some detrimental details on the xs port to do such XR750 oval port modifications in an easy manner, without a machine shop in the background
If you want to indulge yourself more into the history of the D-port, actually it was afaik a makeshift crutch in order to get the flow around the bend of the supercharger inlet of the P51 as it was pretty space restricted.
In case interested go on the Nasa homepage and look for the NACA papers, somewhere in that paper the lowering of the corner velocity together with the raising of overall volumeflow gets discussed
At the end it boils down to fluid mechanics.
All the best and kind regards
Christian
PS: as said I'm also inclined to think that there are unfortunately quite some detrimental details on the xs port to do such XR750 oval port modifications in an easy manner, without a machine shop in the background
As always Christian, you're an encyclopedia of knowledge and I will check out those Naca papers as I had no idea the history D porting went that far back
At the beginning of this thread after the bench was built and I did the initial calibration I was astounded to see how remarkably closely the CFM numbers for my stock head mirrored the stock head numbers that Jack presented. It was aslo evident that the D Port of Garretts tested very similarly to Jacks posted D Port numbers
That moment excited me as it seemed to indicate my calibration was in alignment and made me more anxious to go forward.
Unfortunately that was not the case. Utilizing other aspects and formulas it did not take me long to realize my numbers were not correct at all.
I covered the entire process in the "ReCalibration" video. This was difficult for me to accept at first. The reason is simple.
By using the correct "Bench Coefficient" instead of the "Orifice Coefficient" my flow numbers dropped consoderably.
The Orifice coefficient of 62.5 obviously gives a much larger number than the correct Bench coefficient of 45.3
It is truly all about percentages so those numbers didn't really matter as long as the focus was retained on the important data.
But that was also incorrect. It does matter.
It affects your volumetric efficiency, your discharge coefficient, and other vital data that is necessary to create a well tuned port.
I could have chosen to stay with the formula that had my CFMs comparable with those of Jack, after all; one stock head should test very closely to another stock head, which is what made it more confusing for me at the time. The numbers again with Jack's Data from his thread -
Jack's
cfm stock I:
lift - I cfm - E cfm - E/I flow ratio
100 - 76 - 67 - 88%
200 - 118 - 96 - 81%
300 - 162 - 115 - 71%
400 - 181 - 122 - 67%
My Stock Intake (Inflated)
Lift- CFM
100 -75
200 -118
300 -155
400 -182
Very similar but my numbers were wrong.
It would have been easy enough for me to never have revealed my discovery and continued utilizing the inflated numbers.
That would have been the opposite of my goals in a search for factual accurate information. It would have been dishonest.
It would have also inhibited me from gathering accurate data to create efficient ports. I will demonstrate what I mean.
One of the most important numbers we look at involves port efficiency. How much air we are moving through a given opening.
This opening is the valve curtain area (VD x pi x lift). The more air you can move the more efficient your port at that lift.
However you can move too much which I touched on earlier in the thread under Porting 101 I think.
Since my flow numbers no longer aligned with Jack's I was in a bit of limbo, but I knew the numbers I was creating were correct.
I proved the data in the recalibration video using calibrated orifice plates and verifying those numbers.
I eventually discovered data from other porters that were aligned with my data as well as fitting within all the other formula computations.
So let's dive a bit deeper.
The data we are looking at now is going to be Coefficient of Discharge (CD)
That formula is CFM/VCA (valve curtain area).
The numbers are given in PSI. Let's apply it.
The old Suoerflow maximum standard used to be 146 PSI
Some people still use this number. It is only applicable in the highest output motors with forced induction.
The SAE standard is 136 PSI. This SAE number in practicality is only achieved in motors as above.
High performance race engine is considered 126 PSI. Numbers seen in motors with more cam, induction, exhaust, compression.
Street Engine should be around 116 PSI. Basic street engines
Hot Street somewhere between the latter two.
Generally you can expect a larger number without issues at the lowest lifts (.05,.10) with a good scavenging exhaust.
Jack mentioned Larry Cavanaugh and his head work with Kawasakis.
I have been aware of Larry for some time. He is a legend in the motorcycle porting world.
He has given up some nuggets over time but never really showed his hand completely.
It was a great loss when he passed away. Because of his work he is known across the globe.
Occasionally he would post some of his porting results on his facebook page.
I have attached one of his postings here to take a peek at his numbers.
This is obviously a Kawasaki head and not an xs650.
It is a Kz1000 with a 37.5mm intake valve.
What is of interest is the efficiency of flow (Coefficient of Discharge) acheived by this world class porter.
Again we are not looking at the CFM numbers. Instead our interest is in how many CFM are being pushed per square inch (PSI)
So let's check it out.
.100 - 50.5 CD= 108.67
.200 - 88.1 CD= 95.00
.300 - 128.8 CD= 92.59
.400 - 149.4 CD= 80.54
In comparison....
My MOD 3 Head
MOD 3
.100 - 81.16 CD= 160.07
.200 - 120.66 CD= 118.99
.300 - 144.04 CD= 94.70
.400 - 158.04 CD= 77.93
VERY comparable.
Already an understanding that the lowest flow is too high and needs shifted with this particular design.
The highest flows are what I am spotlighting.
However if I were to use the orifice coefficient I originally calibrated to, we can see some issues.
The example: The same head, same test simply using the old coefficient.
MOD 3 Head @ 62.5
.100 - 112.00 CD= 220.91
.200 = 166.51 CD= 164.21
.300 - 198.78 CD= 130.69
.400 = 218.10 CD= 107.54
Looking pretty spectacular. Hmmmm
Or more accurately pretty FALSE.
Looking at the .400 numbers here although they all reflect the same.
My MOD 3 @ 62.5 had a CD of 107.54
World Class porter Larry Cavanaugh "only" managed a CD of 80.4.
Am I really to believe that I managed to flow 33.5% more air PSI than Larry?????
Now you can begin to understand.
What will the correct numbers show?
Again looking at the .400 numbers etc. etc.
The Cavanaugh head as we just saw had a CD of 80.4.
My MOD 3 head flowed 77.93 which is 2.47 CFM less than the world renowned porter.
Far more reasonable. It is this kind of basic knowledge that people should pay attention to.
Even those that may never port themselves but perhaps desire to have work done.
There are several other formulas that can illustrate the veracity of flow numbers.
I will get into some of that down the line...
Just for grins let's look at the stock head efficiency.
My stock head numbers at the correct coefficient.
.
100 - 54.55 CD=107.59
200 - 85.83 CD= 84.64
300 -112.16 CD= 73.74
400 -132.77 CD= 65.47
More coming....
That moment excited me as it seemed to indicate my calibration was in alignment and made me more anxious to go forward.
Unfortunately that was not the case. Utilizing other aspects and formulas it did not take me long to realize my numbers were not correct at all.
I covered the entire process in the "ReCalibration" video. This was difficult for me to accept at first. The reason is simple.
By using the correct "Bench Coefficient" instead of the "Orifice Coefficient" my flow numbers dropped consoderably.
The Orifice coefficient of 62.5 obviously gives a much larger number than the correct Bench coefficient of 45.3
It is truly all about percentages so those numbers didn't really matter as long as the focus was retained on the important data.
But that was also incorrect. It does matter.
It affects your volumetric efficiency, your discharge coefficient, and other vital data that is necessary to create a well tuned port.
I could have chosen to stay with the formula that had my CFMs comparable with those of Jack, after all; one stock head should test very closely to another stock head, which is what made it more confusing for me at the time. The numbers again with Jack's Data from his thread -
Jack's
cfm stock I:
lift - I cfm - E cfm - E/I flow ratio
100 - 76 - 67 - 88%
200 - 118 - 96 - 81%
300 - 162 - 115 - 71%
400 - 181 - 122 - 67%
My Stock Intake (Inflated)
Lift- CFM
100 -75
200 -118
300 -155
400 -182
Very similar but my numbers were wrong.
It would have been easy enough for me to never have revealed my discovery and continued utilizing the inflated numbers.
That would have been the opposite of my goals in a search for factual accurate information. It would have been dishonest.
It would have also inhibited me from gathering accurate data to create efficient ports. I will demonstrate what I mean.
One of the most important numbers we look at involves port efficiency. How much air we are moving through a given opening.
This opening is the valve curtain area (VD x pi x lift). The more air you can move the more efficient your port at that lift.
However you can move too much which I touched on earlier in the thread under Porting 101 I think.
Since my flow numbers no longer aligned with Jack's I was in a bit of limbo, but I knew the numbers I was creating were correct.
I proved the data in the recalibration video using calibrated orifice plates and verifying those numbers.
I eventually discovered data from other porters that were aligned with my data as well as fitting within all the other formula computations.
So let's dive a bit deeper.
The data we are looking at now is going to be Coefficient of Discharge (CD)
That formula is CFM/VCA (valve curtain area).
The numbers are given in PSI. Let's apply it.
The old Suoerflow maximum standard used to be 146 PSI
Some people still use this number. It is only applicable in the highest output motors with forced induction.
The SAE standard is 136 PSI. This SAE number in practicality is only achieved in motors as above.
High performance race engine is considered 126 PSI. Numbers seen in motors with more cam, induction, exhaust, compression.
Street Engine should be around 116 PSI. Basic street engines
Hot Street somewhere between the latter two.
Generally you can expect a larger number without issues at the lowest lifts (.05,.10) with a good scavenging exhaust.
Jack mentioned Larry Cavanaugh and his head work with Kawasakis.
I have been aware of Larry for some time. He is a legend in the motorcycle porting world.
He has given up some nuggets over time but never really showed his hand completely.
It was a great loss when he passed away. Because of his work he is known across the globe.
Occasionally he would post some of his porting results on his facebook page.
I have attached one of his postings here to take a peek at his numbers.
This is obviously a Kawasaki head and not an xs650.
It is a Kz1000 with a 37.5mm intake valve.
What is of interest is the efficiency of flow (Coefficient of Discharge) acheived by this world class porter.
Again we are not looking at the CFM numbers. Instead our interest is in how many CFM are being pushed per square inch (PSI)
So let's check it out.
.100 - 50.5 CD= 108.67
.200 - 88.1 CD= 95.00
.300 - 128.8 CD= 92.59
.400 - 149.4 CD= 80.54
In comparison....
My MOD 3 Head
MOD 3
.100 - 81.16 CD= 160.07
.200 - 120.66 CD= 118.99
.300 - 144.04 CD= 94.70
.400 - 158.04 CD= 77.93
VERY comparable.
Already an understanding that the lowest flow is too high and needs shifted with this particular design.
The highest flows are what I am spotlighting.
However if I were to use the orifice coefficient I originally calibrated to, we can see some issues.
The example: The same head, same test simply using the old coefficient.
MOD 3 Head @ 62.5
.100 - 112.00 CD= 220.91
.200 = 166.51 CD= 164.21
.300 - 198.78 CD= 130.69
.400 = 218.10 CD= 107.54
Looking pretty spectacular. Hmmmm
Or more accurately pretty FALSE.
Looking at the .400 numbers here although they all reflect the same.
My MOD 3 @ 62.5 had a CD of 107.54
World Class porter Larry Cavanaugh "only" managed a CD of 80.4.
Am I really to believe that I managed to flow 33.5% more air PSI than Larry?????
Now you can begin to understand.
What will the correct numbers show?
Again looking at the .400 numbers etc. etc.
The Cavanaugh head as we just saw had a CD of 80.4.
My MOD 3 head flowed 77.93 which is 2.47 CFM less than the world renowned porter.
Far more reasonable. It is this kind of basic knowledge that people should pay attention to.
Even those that may never port themselves but perhaps desire to have work done.
There are several other formulas that can illustrate the veracity of flow numbers.
I will get into some of that down the line...
Just for grins let's look at the stock head efficiency.
My stock head numbers at the correct coefficient.
.
100 - 54.55 CD=107.59
200 - 85.83 CD= 84.64
300 -112.16 CD= 73.74
400 -132.77 CD= 65.47
More coming....
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@Hudriwudri
Hello Christian.
Thanks for the kind words.
I also appreciate any and all nuggetts.
You are very well known among those porting motorcycles.
I have followed some of your work when I have been able.
I believe you were working a lot of TT500 ??? but I it's been a minute so maybe I got that mixed.
I appreciate the tips...
I was unaware of the Access Norton until Jack mentioned it.
Obviously would have to be modified to fit an xs650 head but I found it very interesting.
Once I get this sorted out I am thinking I may pursue it.
The concept is very similar to one of the designs I have been working toward.
Too much on the plate at the moment to dive in but I think it could be possible.
I found a good bit of info as well as some templates and port maps so it is a good start when I do get it going.
Obviously that information will have to be altered/modified.
I can relate to the busy home life and work loads.
It is good to be in demand.
Happy you could make the thread.
Stay safe and healthy...
Regards,
Rick
Hello Christian.
Thanks for the kind words.
I also appreciate any and all nuggetts.
You are very well known among those porting motorcycles.
I have followed some of your work when I have been able.
I believe you were working a lot of TT500 ??? but I it's been a minute so maybe I got that mixed.
I appreciate the tips...
I was unaware of the Access Norton until Jack mentioned it.
Obviously would have to be modified to fit an xs650 head but I found it very interesting.
Once I get this sorted out I am thinking I may pursue it.
The concept is very similar to one of the designs I have been working toward.
Too much on the plate at the moment to dive in but I think it could be possible.
I found a good bit of info as well as some templates and port maps so it is a good start when I do get it going.
Obviously that information will have to be altered/modified.
I can relate to the busy home life and work loads.
It is good to be in demand.
Happy you could make the thread.
Stay safe and healthy...
Regards,
Rick
Indeed.
It is not your CFM numbers I even look at. I study your percentages.
It is all about your gains, Both the gains over stock as well as the gains between lifts.
They are impressive.
You've got to be kidding me, are you saying my good friend has been misleading me with inflated #s for all these years? I'm
truly lost for words here and beyond embarrassed that he would do that to me. Everyone, please accept my apologies and
Thank You Bluz for bringing this unfortunate information to my attention.
I didn't say anything about your numbers Jack.
I was talking about MY numbers on MY bench.
As I stated, the two are not comparable. From the beginning I have said that the only intereest in in percentage of gains.
It was coincidental perhaps that the numbers aligned initially.
I have not once said anything about your numbers being wrong.
I made the error in my original calibration using the coefficient of the orifice plate because that was how it was initially explained to me. There were issues with the numbers. I owned it and demonstrated the how and why in the recalibration video. The testing doesn't lie.
Everything I have presented not only can be but has been repeated and repeated.
Everything I do is based on data which is specific to MY bench.
I have made it abundantly clear that I have NOT tested your head, only a copy that was obviously not built to your standards.
Your head's flow numbers are correct on the bench it was flowed on. That bench was a calibrated Superflow.
Your head tests repeatedly the same so I see no issue. If you are happy it is all that matters.
Of all the testing I do the CFM numbers are the LEAST important data.
For some people it is the only data and the only data that matters.
There are many ways to skin a cat.
This posting is not about your head or your numbers. It is an explanation of how I arrived at the correct calibration for MY bench and how those numbers are verified using standard formulas utilized by almost everyone in the porting world. Formulas which have been created and tested by SAE among others.
My numbers are correct on my bench. I can verify my numbers in numerous ways and have done so.
It is unfortunate that you choose to take the approach that I have said anything about your numbers being misleading.
All I have done is present factually the journey I have undertaken in making certain that my bench is accurate and I have data that is reliable.
I didn't create the formulas or the laws of fluid dynamics. They exist.
Reconciling your head's performance with those realities is up to you.
I prefer ALL the data to be in alignment when porting a head.
If something is standing alone way out of the box it is an issue that should require more investigation and be resolved.
If you take offense to me sharing data and explaning how it is inter-related, I apologize.
I don't understand how that becomes personal for you.
But that is what this is going to be about. DATA. Formulas used for verification or to identify issues.
Flowing some CFM and calling it a day just isn't enough.
I was talking about MY numbers on MY bench.
As I stated, the two are not comparable. From the beginning I have said that the only intereest in in percentage of gains.
It was coincidental perhaps that the numbers aligned initially.
I have not once said anything about your numbers being wrong.
I made the error in my original calibration using the coefficient of the orifice plate because that was how it was initially explained to me. There were issues with the numbers. I owned it and demonstrated the how and why in the recalibration video. The testing doesn't lie.
Everything I have presented not only can be but has been repeated and repeated.
Everything I do is based on data which is specific to MY bench.
I have made it abundantly clear that I have NOT tested your head, only a copy that was obviously not built to your standards.
Your head's flow numbers are correct on the bench it was flowed on. That bench was a calibrated Superflow.
Your head tests repeatedly the same so I see no issue. If you are happy it is all that matters.
Of all the testing I do the CFM numbers are the LEAST important data.
For some people it is the only data and the only data that matters.
There are many ways to skin a cat.
This posting is not about your head or your numbers. It is an explanation of how I arrived at the correct calibration for MY bench and how those numbers are verified using standard formulas utilized by almost everyone in the porting world. Formulas which have been created and tested by SAE among others.
My numbers are correct on my bench. I can verify my numbers in numerous ways and have done so.
It is unfortunate that you choose to take the approach that I have said anything about your numbers being misleading.
All I have done is present factually the journey I have undertaken in making certain that my bench is accurate and I have data that is reliable.
I didn't create the formulas or the laws of fluid dynamics. They exist.
Reconciling your head's performance with those realities is up to you.
I prefer ALL the data to be in alignment when porting a head.
If something is standing alone way out of the box it is an issue that should require more investigation and be resolved.
If you take offense to me sharing data and explaning how it is inter-related, I apologize.
I don't understand how that becomes personal for you.
But that is what this is going to be about. DATA. Formulas used for verification or to identify issues.
Flowing some CFM and calling it a day just isn't enough.
AUTOMAN
XS650 Addict
Keep on learning. This post is cool to see.
Aero-dynamics are so cool.
Various densities, velocities, mass flows and most important Reynolds numbers.
cliff
Aero-dynamics are so cool.
Various densities, velocities, mass flows and most important Reynolds numbers.
cliff
Been a bit busy...
With the bench and life.
I have now calibrated my pitot tube.
In fact it was actually very close already out of the box.
Now I am able to measure the actual velocity for purposes beyond comparison.
The reason this is an important step has to do with having the ability to detect when areas of the port reaches excessive speeds that can cause choke.
There are various ways of determining this value which I will discuss upcoming.
I bring this up as I have now approached those numbers in my latest tests.
I have been getting nearer to a final design decision.
However, recent discussions in the thread regarding information from Access Norton have veered me off course.
Only the initial attempt at meshing some of those ideas with my present studies..... But I must say the data looks great.
Flowing the highest velocities I have seen to date. The CFMs are similar to my best testing so far.
But we know it is about that velocity.
I will be running the full battery of testing on this before modifying further.
I should have those tests completed sometime tomorrow.
Hopefully I'll be able to compile the data and present it shortly thereafter.
I believe this is a bit of a breakthrough, but the tests will ultimately determine if so and how much.
It is finding these kinds of discoveries that make this worthwhile.
Contributions from others in this thread pointed the way and opened the door.
Hit or miss you'll get the full report...
With the bench and life.
I have now calibrated my pitot tube.
In fact it was actually very close already out of the box.
Now I am able to measure the actual velocity for purposes beyond comparison.
The reason this is an important step has to do with having the ability to detect when areas of the port reaches excessive speeds that can cause choke.
There are various ways of determining this value which I will discuss upcoming.
I bring this up as I have now approached those numbers in my latest tests.
I have been getting nearer to a final design decision.
However, recent discussions in the thread regarding information from Access Norton have veered me off course.
Only the initial attempt at meshing some of those ideas with my present studies..... But I must say the data looks great.
Flowing the highest velocities I have seen to date. The CFMs are similar to my best testing so far.
But we know it is about that velocity.
I will be running the full battery of testing on this before modifying further.
I should have those tests completed sometime tomorrow.
Hopefully I'll be able to compile the data and present it shortly thereafter.
I believe this is a bit of a breakthrough, but the tests will ultimately determine if so and how much.
It is finding these kinds of discoveries that make this worthwhile.
Contributions from others in this thread pointed the way and opened the door.
Hit or miss you'll get the full report...
Might be interesting to flow test a Bob Bertaut head??? ;^)
