Not the Mercdog again

[storm]

You could do a great deal worse than pay some serious attention to the consensus here on the Forum.

The problem Old Grey has is he is the labourer not the engineer. The thing has already been built it is a patch/repair job now and the owner is the person who needs convincing not Old Grey.
If I were Old Grey I'd be telling the owner to get on here, read everything, and then if he still wants it done to have a serious think about how its going to be done and how much time and money he is willing to spend on it.

[Old Grey]

The Forum certainly has been around for a very long time, and it now links a very large number of people with a serious interest in flow bench construction and testing from all around the world.

Over the years, a great deal of thought, experimentation and testing has been carried out by Forum members, and bit by bit, by trial and error, a very solid knowledge base has gradually built up.
Progress in the art of flow bench construction has been continuous, and is STILL moving forward.

You could do a great deal worse than pay some serious attention to the consensus here on the Forum.

None of us individually could have achieved what we as a group have achieved collectively, and its a truly wonderful thing to see evolving, when people freely share and help each other.

True, but most of the stuff stated has never been backed up with actual posted numbers, so to an outsider it seems like an opinion - I still don't have proof the PTS DM can read small numbers -.

Example, we were told that you can't put an orifice in a tube, and that you need a minimum area ratio above and below the orifice. And even though that test was actually done, there were never any figures posted so that other people can analyse them and maybe look at them from another perspective.

There is critical information missing, like in 2007 the pitot was all the rage, but when I came back in 2014 everyone switched to orifice. There was never figures posted explaining it, nor even a reason, so I had to ask in a post what happened, so that I could decide what to do.

The forum is has been invaluable, but without numbers every test will have to be constantly duplicated. This is the reason this topic has gone on so long, because I've provided all the info I found so that you can decide and not have to duplicate it. Look what's been discovered, larger internal orifices can utilise higher flow rates up to a point, a manometer sensing tube with pin holes may have merit - also some secret things -, and all with figures to back it up.

The forum isn't complete, but because it's so old, if you ask question, people aren't that interested and only give a cursory reply. It's like Bruce sent out an email to get more people involved, yet I have 2 topics that didn't even get 1 response.

I'm just using what I'm given and trying to get on with this time and money pit. Even though this is an anchor, I will definitely spare more time for anyone that needs help - which I have done in PMs -, because I know help is hard to come by.

[Tony]

There is critical information missing, like in 2007 the pitot was all the rage, but when I came back in 2014 everyone switched to orifice. There was never figures posted explaining it, nor even a reason, so I had to ask in a post what happened, so that I could decide what to do.

I will just pick this part out to comment on.
Sorry you missed the now almost universal conversion over to orifice style home built benches, there was quite a lot of discussion about this at the time.
Its so clear cut, that all discussion about the subject ceased a very long time ago and is never now mentioned.
So its probably time for another revisit.

Basically, a pitot style bench measures air impact pressure in some kind of pitot probe or averaging tube, and you then need to apply fairly complex correction factors to turn that into a final CFM figure, supposedly corrected back to to "standard sea level temperature and pressure".

The whole process is prone to multiple measurement and number crunching errors, and you just need to place total faith in the whole conversion process required to reach some final "corrected" CFM figure.
If it all turns out a bit wrong, it is very difficult to know where the error crept in, or what you need to change to fix it.
As the correction factors change from day to day, and hour to hour, bench repeatability usually suffers.

A ratiometric flow bench simply feeds the EXACT SAME AIR first through what you are testing, and then through a known reference orifice plate.
Air "quality" then becomes irrelevant, as the same air flows through both restrictions placed in series.
Barometric pressure, temperature and humidity have zero effect on the resulting measured pressure ratio number.
By that I mean the ratio between the two measured pressure drops across port and orifice.

There is an exact inverse square law relationship between differential pressure and CFM, and all you then need to know is a calibration figure for the particular orifice plate.

You can test the same port against the same orifice plate in freezing sub zero winter conditions, or on a hundred degree plus humid summer afternoon, or up a 10,000 foot mountain, and the measured pressure ratio between port and orifice will come up the exact same ratio every time.
It is so simple, and because no "ambient corrections" are required, is also much more repeatable.

All you need are the two direct pressure readings.
Differential test pressure, and differential orifice plate pressure.
That is all there is to it.
No corrections need be applied.
Once you understand the pure simplicity of a ratiometric orifice bench, a pitot bench is just a complete non starter.

Its not a case of comparing accuracies between the two different types of bench, and having long drawn out debates about it all.
A ratiometric orifice bench is vastly simpler in both concept and operation, much easier to use, and the much better repeatability comes for free.
The greater simplicity also potentially increases the accuracy, as fewer and simpler steps are required to get a final CFM figure.

[1960FL]

Grey,

Well I made a very rough sharp edge orifice - 3.33" 0.572 cd - and it's pretty much the same.

Just how are you determining what the CD Value is?

Rick

I just keep adjusting it until it reads what the PAP flows.

That sharp edge orifice is so rough that that I can't actually measure the diameter accurately so It could actually be smaller with a higher cd, which would explain why it's down on dep by 3" when flat out with the 6 motors. The 3mm square edge orifice is 3.33" 0.576 cd

I wish the thing was closer to what it's supposed to be, but that's just what it is.

The 40" FP1 with the old single hole on the end of a tube came out as
A = 2.54" 0.067 int - cal PAP 200cfm
B = 2.54" 0.735 exh - cal PAP 200cfm
C = 3.33" 0.630 int - cal PAP 300cfm
D = 3.33" 0.570 exh - cal PAP 300cfm

So I have read this thread , tried to contribute and all around was interested in what you were doing even though you are not so welcome to others input just pushing forward with what you want to do, looking for the answers you like and purporting your advanced knowledge of this subject yet continually asking the basic questions.

Even though this forum has been around a long time, there are still things it doesn't know - There are critical things I found out that have never been discussed -. There is a general disinterest in the forum unless you run a PTS, so outsiders are always going to be on their own to slug it out.

Oh Please do share!

If you look at my first quote it goes back to the basic questions and issues, you are not hearing what you want to so you push it aside and look for more of the same... First issue, you cannot make an orifice multiple times the same way out of the same metal and have that big a difference in CD!

That sharp edge orifice is so rough

I sure hope you are not speaking about the PAP plates as that would be pure nonsense and anyone who has purchased Bruce's plates knows that. That said your pictures appears to me that you are using a square edge internal orifice in your rotating plate.

Grey there are many things on this forum that were lost from the early days do to ISP server issues and software crashes, I personally recovered as much as I could for Bruce, as for the discussion of transition from Pito to Orifice it was a beaten horse and all I can say is to build a Pito bench that could equal the performance of the PTS design would require 4 to 5 times the cost of materials and a BOX about 4 times as big not to mention it is not ratiometric.

This is not a flow bench race as there are no winners in that game! I think what you are working on is interesting and holds my attention on the forum and one day when I have to much time on my hands I may go down the same rabbit hole with one of my projects. But if your intention was to build a bench that was to be used to test heads and get on with engine building you most likely would of realized long ago that technology and design has changed the game and you are just wasting your time, money and energy continuing down the path you are going as stated early on in this thread. Nothing will beat a motor control for varying depression or a symmetrical box design and if it is to much work to change an internal orifice once in a blue moon (need for rotating disk) you are in the wrong game as bolting heads with intake radius and installing the valves and keepers between incremental porting session is 100 time more work.

In closing to pass on some knowledge to all, if you have to adjust your orifice CD for each range/size of internal orifice all manufactured in the same manor (see above numbers) then this is a key sign that the air inside your bench does not continue to flow in a symmetrical uniform manor to the orifice...... thus it is a marker to a poor bench design elements......

Last before ever building a bench do the math to size what it is you will be working on if we use a simple formula of .2537 X CFM = HP Potential based on air How much do we need to flow REALY! Example my bench with $6.00 junk motors will flow over 500 cfm at 28" or the equivalent of 127 Hp per port! Sooo with what I work on i use a 340 CFM internal plate and it will cover the whole scale of my flow testing and is within 1cfm in calibration using a textbook sharp edge CD of +/- .62; Alsot my other internal plates 250 cfm and 500 cfm calibrate in at =/- 1cfm with a +/- .62 CD. My actual intake mode CFM for all my internal plates works out to a uniform acceptable calibration at a .6187 CD (+/- .62 ). As for range the 340 internal plate will also flow down to 25CFM repeatedly within 1/2 a cfm. Anything you can do to promote full/laminar flow inside the bench promotes ease and consistency of calibration across the range not to mention more stable numbers.

Rick

[Old Grey]

So I have read this thread , tried to contribute and all around was interested in what you were doing even though you are not so welcome to others input just pushing forward with what you want to do, looking for the answers you like and purporting your advanced knowledge of this subject yet continually asking the basic questions.

I'll have to explain these in blocks because there is so much.

Even though you are not so welcome to others input just pushing forward with what you want to do.

But you could really say the same thing about the senior members on the forum. There is this kind of misunderstanding or lack of apathy to peoples situations because the panel is sort of set in its ways.

We can take the Kimi incident as an example.

Everyone was telling Kimi that his orifice in a tube is flawed, and that he should go to a cabinet. But Kimi didn't listen, and everyone got super angry - even me - because he wasn't doing what he was told.

Now that I look back at it I realise that myself and most of the panel were probably wrong, not wrong in actual facts, but more a misunderstanding of the situation.
Look at it from Kimi's stand point.
He's new to the forum, so wouldn't know anyone username from a bar of soap. So in his mind anything presented is opinion not fact.
No one actually produced any proof of what they were suggesting. So again it's not creditable in his mind, but just an opinion.
No one asked him what his situation was. Maybe he didn't have the money for something better. Maybe he was just cobbling stuff together as an experiment. Maybe he is only ever going to do one head in his life and just wanted something simple. The point is no one asked.
To Kimi it probably seemed like people were telling him what he was doing was junk and that he was stupid, so he just ignored it. I would have ignored it too, and I bet everyone on the forum would have done the same in the same situation at that knowledge level.

Just thinking about the Kimi post lately, and why he didn't know about the orifice in a tube phenomena, and it got me thinking. We all know and accept the fact that the flow readings are not liner with an OiaT, but if you look back only one person actually did the experiment, and there is no record on the forum of any results. We are basically accepting one person's opinion without proof, or actual numbers. We can't analyse his methodology, because it was never explained, and that means that we might have seen something that the guy didn't account for - it's why I detailed so much in my experiments so that other people will correct me -. Peer review makes things more accurate. I know Bruce has long conversations with members, but that is always behind closed doors so that no one can put in different perspectives. You know stuff I don't know, I know stuff you don't know, together we probably know everything.

Another example is that Larry attacked me for making a manometer

You're doing two things wrong.
1 - Making everything way, way, way harder than it has to be.
2 - Creating a water manometer scale from a digital unit that is not at all designed for such work.
I'm not going to get into the how & way. You'll just disregard the advice like you have from the beginning of this thread...

This was kind of wrong. Instead of asking "why I are you now making a manometer?", he just attacked without bothering to know the situation. I though it was pretty obvious with the 10 pages of recorded writings how I made a graphical manometer, that it would be pretty obvious that it wasn't my doing, nor important.

I reread all the orifice posts a while back, and it might not be something that the panel sees, but this is what the forum looks like from the outside.

The first thing that happens in a post where someone is building something custom, is that Bruce suggests switching to the PTS FB. Now he has every right to suggest the PTS because he has to make a living, but in the early day he was so adamant and unyielding that it got annoying. It kind of felt like he was saying to throw away your work and ideas because there is only one right way to make a FB. I think he kind of realised that it was coming across too strong, so he only mentions it once these days, but usually the people in the alternative FB sections have a reason why they didn't go PTS. He might be right long run, but he hasn't really accounted for personal situations.

The PTS is practically a small business FP, because it's a 180 hour $1500 commitment. I was helping a chap by PM with his PTS and he was taken quite aback at the 180 hours. I explained that that was normal, but I think the simple $50 entry didn't really prepare him for the commitment. After questioning his situation I realised he would have been better off with a SF110 and a DM
Now lets look at the practically of the PTS for someone without a small business :-
Image you will only ever do your own personal head, and that now makes the 180 hour $1500 commitment overkill.
Imagine you don't have any income but have time - like me -. You cant actually build anything to any plans because you have to use what you can find, and that doesn't usually fit set plans.
The PTS isn't that small, and maybe people don't have the room.

I'm not saying the PTS is bad, it's great and I wished I had one, but the panel needs to step back and remember that some people just can't have one.

The second thing I notice is that the panel tells you to do something without really explaining why. It's like, "don't use OiaT", "why", ................ A simple reference to a post would fix everything, but unfortunately most of the facts are hidden in people minds and aren't posted for prosperity. The panel knows every post, so could reference them a lot faster than the 40 hours that it took me to read all the orifice posts to try to find the MSD related stuff, but it kind of just puts in the minimum.

I notice that the panel puts in the minimum effort, gets bored, and leaves a post rather quickly. Maybe the hidden PTS stuff runs red hot with help, but I don't really see that on other sections, and especially if it's odd ball. It's basically all up to you if it odd ball, so you can't really follow recommendations if none come.

Welcome to all the new PTS Friends this past month! I'm not one for making alot of updates here in FB but the PTS Flowbench Forum is active with info exchange on a daily basis. If you are not already a member I suggest you register, costs nothing but lets you see so much more info:

This appeared on the FB page, so I though I will post to try and help, but it's kind of hard to do because there is no feedback, no community, no incentive. It's like you get talked down to anyway, so why bother. Sure you guys know a lot, but if you don't nurture, don't complain if you get ignored.

Even though you are not so welcome to others input just pushing forward with what you want to do.

This statement is actually wrong because I always took advice. What you didn't know was that there were 2 factions with 2 opposing views that neither knew about, and I had to make the judgement which way to go. I will explain the orifice saga latter when I have time, but can you see how people get attacked because other people don't know the situation. I'm the only one that knows all the facts, so in reality I'm the one in the best position to make the decision, so if it didn't fall your way there is a reason you probably don't know about.

If you want to know why I did something, just ask, but don't get upset if it's not what you expected, because when you know the facts you will see I was probably right.

I know the forum is in decline, and that you have to look for everything in the hope that someone recorded it because you won't get any help, but it is kind of frustrating for people when they ask for help and none comes. It's like when I asked for the SF600 orifice plate thickness and no one replied. I know that Bruce measured it yet he didn't reply with a thickness nor an explanation the he forget to measure it. It's feels like you're on your own if you do something different to the panel recommendations, when they don't understand the situation. I don't really need the thickness, it's just that it would be interesting to know at what thickness SS stops warping when cut with a laser.

Don't take this post the wrong way, the forum is what it is these days, just accept different view points and be more understanding.

[Brucepts]

It's like when I asked for the SF600 orifice plate thickness and no one replied. I know that Bruce measured it yet he didn't reply with a thickness nor an explanation the he forget to measure it. It's feels like you're on your own if you do something different to the panel recommendations, when they don't understand the situation. I don't really need the thickness, it's just that it would be interesting to know at what thickness SS stops warping when cut with a laser.

Actually, no I never have measured the SF600 plate so I was not able to post this info. The plate hole dimensions were supplied by someone else to me but not the thickness. I'm sure you could research at what thickness SS warps from laser cutting, I lathe cut all my orifice plates so I would not be able to supply that info so I did not reply. Do I need to reply to every post on the forum? If I have no info to share should I just post a reply anyway? Did you call or email SF and ask them how thick it was??

I have no desire to reverse engineer a SF flowbench, I know and seen enough about the design to know it's not something I need to research

The PTS is practically a small business FP, because it's a 180 hour $1500 commitment. I was helping a chap by PM with his PTS and he was taken quite aback at the 180 hours. I explained that that was normal, but I think the simple $50 entry didn't really prepare him for the commitment. After questioning his situation I realised he would have been better off with a SF110 and a DM

180 hours normal for a PTS Flowbench build???? Where did that number come from? How many have you built to know that? Why would you offer advice on a PTS build when you have never even built one? I know some that have built it in a weekend! The level of time spent yields a different level of finish. I have had people who last week had no clue what a flowbench was to testing parts the next week, to then offering flowbench services to others and started their own business! Probably 10-15 people that I could put in that category. Doesn't take long to payback a $1500 investment that way does it? Plans are priced at $50 to add a level of commitment to the build if I priced them less I could sell lots of plans but how many would finish a flowbench? Yes, I would make $$$'s from selling plans but how many would get built? My GOAL is to help people build a flowbench that works right the first time and understand how to use it!

I ask nobody what their "situation" is that is none of my business! They have to determine what they need and can afford to do. I will offer advice behind closed doors once they offer their "situation" to me and help them with a build. Sometimes it's not with PTS parts either. If someone wants to talk flowbench outside the forum and some do I can be reached via email, PM, text or phone call.

95% of the people who now come to the forum have no desire or time to research and simply would like to build a proven flowbench design so they can test parts. Yes, we have changed the flowbench community and the DIY aspect of the forum is slowly dying away but, the info is still here for research. With, I would speculate +300 PTS flowbenches now up and running should I spend my time supporting that or a one off build? Those 95% are not interested in designing and building a flowbench from scratch, the forum info allows you do just that but you have to research that info as you are finding out.

Yes, I make money off my parts. I'm not solely making a living doing this by any means I keep my prices as low as I can to help everyone build a flowbench. You can build the PTS style flowbench without using any of my parts or plans but you have to do the research, my plans and parts allow you to get started right away so you have to put a value on your time? Some have more time than money, I have neither so it is a balancing act as to what I spend my time/money on.

Since putting my phone number on my website a few years ago over 50% of the calls I receive and help are from people who do not even have any PTS products nor are members of this forum or even heard of it. I probably talk to more people who are working with SF600's than I do with a PTS flowbench build! I've spent many hours helping some calibrate another vendor's flowbench to sell 1-3 orifice plates?

I get accused of profiting from the forum but do you know how many of the vendors selling flowbench products now started here on the forum? It's ok for them to go out and start a business selling parts with info gleaned from this forum over the years? Where do people go to get support for those products? Yup right back to this forum imagine that! This thread about Mercdog is proof to that

There is nothing hard about building a PTS Flowbench, it can be done with simple hand tools ie a circular and jig saw, router and cordless drill some glue and screws. 3 sheets of MDF and some melamine pieces. Scrounge up some vacuum motors, a cheap router control for motor speed some clear tubing and some math and you have a simple water gauge flowbench! This is how I built the one I use daily in my shop. Add better motors and speed control, digital gauges some other little bits to make life easier and you can have a serious professional quality flowbench!


Nobody pays anything to join this forum, I make no money from advertisements on this forum or my website, the info is free, use it as you see fit!

[Old Grey]

Grey,

Well I made a very rough sharp edge orifice - 3.33" 0.572 cd - and it's pretty much the same.

Just how are you determining what the CD Value is?

Rick

I just keep adjusting it until it reads what the PAP flows.

That sharp edge orifice is so rough that that I can't actually measure the diameter accurately so It could actually be smaller with a higher cd, which would explain why it's down on dep by 3" when flat out with the 6 motors. The 3mm square edge orifice is 3.33" 0.576 cd

I wish the thing was closer to what it's supposed to be, but that's just what it is.

The 40" FP1 with the old single hole on the end of a tube came out as
A = 2.54" 0.067 int - cal PAP 200cfm
B = 2.54" 0.735 exh - cal PAP 200cfm
C = 3.33" 0.630 int - cal PAP 300cfm
D = 3.33" 0.570 exh - cal PAP 300cfm

This was actually a trick I used to illicit a response by peer review.
At the time I assumed that incorrect CD's were normal because nearly every FB calibration that has been posted on this forum has never hit the correct cd. Also I noticed that you have to change the cd by quite a large amount to make a difference, so I didn't think much of it. But then I though that I better over supply information just in case, and see if someone sees something. Well someone did, but without any actual info on where to look, just that it looked funny, and that got me thinking why. I found the major leak that was throwing out the initial readings, but what I didn't realise was that the other connections were weeping too. What I did was double every connection, and suddenly the readings were a lot closer to the cd. If you read further on you will see it was all explained already in subsequent entries.

People say I never follow advice, but here is just another example where I did, it's just that the advice was so vague you're stuck working it out yourself.

Here is my solution, a bit of soap and the next sized tube slid on.

[Old Grey]

Bruce, you should profit from the forum because you do a good job and it's a lot of work. I'm not really interested in the profit side, just the support side.

You kind-of should answer questions even if you don't know the answer, because it makes people think the forum is active. If you posted that explanation I would have been very happy, but because it wasn't answered the general forum seems disinterested and makes people feel any contribution is a waste of time.

180 hours was what I was quoted by the constructor and the wood was precut, so add those hours in and it's even more. Mine were both over 200 hours, so it's quite feasible for a first timer that is fussy about quality taking that long. It's that classic case where the first time takes a long time, and each subsequent one takes less time. I'm sure you could knock one up quick, but look at a first timer that works with metal, and now has to work out how to use wood.

I've seen the plans and the insides of a PTS, so I know something about them.

Phone conversations are a single use thing that ends up lost, so it's probably more beneficial to post more and reference stuff, because it saves repeating.

It's up to you what you want to do, but after spending 40 hours reading the Orifice FB section and others, you get the distinct impression that responses are minimal, and then it's up to you. Maybe it's the same in the PTS section, but I won't know because I don't go there. There are lot of cases in the forum where no asks the situation, so you get talked down too for doing something different, so maybe someone should ask for the situation, or a least not be judgemental.

It's just a bit depressing for me because the forum was a thriving community of enthusiastic people, and now it's a bit jaded.

Look on the bright side, this post has had 6000 views, at least it's not boring.

I will keep slogging it out and post what I find, just so no one has to go through all the pain I went through finding info, and trust me it's pretty depressing working for $3/hr.

[storm]

You kind-of should answer questions even if you don't know the answer, because it makes people think the forum is active. If you posted that explanation I would have been very happy, but because it wasn't answered the general forum seems disinterested and makes people feel any contribution is a waste of time.

I disagree with this. I run a small Linux forum and some people whine about not getting an answer. If the question is written well (meaning the reader can easily understands what is being asked) and it doesn't get an answer it means that the people who have read it don't know the answer. I, personally, would much prefer no answer if people don't know (or can't figure it out) than to get an answer that is wrong or worse still can cause further problems.

[Old Grey]

You kind-of should answer questions even if you don't know the answer, because it makes people think the forum is active. If you posted that explanation I would have been very happy, but because it wasn't answered the general forum seems disinterested and makes people feel any contribution is a waste of time.

I disagree with this. I run a small Linux forum and some people whine about not getting an answer. If the question is written well (meaning the reader can easily understands what is being asked) and it doesn't get an answer it means that the people who have read it don't know the answer. I, personally, would much prefer no answer if people don't know (or can't figure it out) than to get an answer that is wrong or worse still can cause further problems.

Sorry, I assumed Bruce measured the disk because he posted the picture, and even though he didn't know the thickness, he did know the the person did not post a thickness. That information would have given closure and forum confidence, so that people will get involved.

I'm not really talking about the wrong answer, it's just that a blank post tells you nothing, Did no one see it, does no one know, does no one care. I rather know that no one knows, than be in limbo. Plus you get more hits if you answer.

I ran a help line and would answer everything, but when I gave up it died. No support, no forum.

It's like the Facebook page asks you to post, but the people on the forum say they shouldn't contribute, it's kind of weird.

I keep writing on this post, and people keep reading this post, it kind of proves that you have to get involved or it's going to die.