Dart 180 cc alloy head as cast

[steve cowan]

Everything I do here with my CNC stuff is done at 50".. You will see stuff at that pressure you don't at 28"..

on my bench i can flow 400cfm @ 28''
i have checked cfm and velocity to 40''
i think it could go 45'' on a small port or exhaust port.
my pitot is electronic and can be corrected to depression used but i only use pitot at the actual depression test at that time.

[CGT]

I wonder if people on construction forums talk about the best way to build something using the industry stnd measurements and lingo or if they just turn everything into arguing that 1 foot really isn't a foot?

It is just strange that the few who want to start this argument year after year after year after year use the same tools and industry standards when developing their engines as the rest of us.

I see no argument here over the need to have standards, they are in place and are useful ,somewhat necessary in terms of being able to have conversations with others doing similar things...people talk flow in terms of 28" or cams in terms of .050 duration, these give you a quick glimpse into what your dealing with although they may mean a lot or not much at all...

Its the application of that data, and what it means to you, whether based on history, software etc.. that seems to get people excited. I think sims and software are tools, more useful to some than others, how useful may depend on where your "at" in the grand scheme of things. Going outside of a sim isn't ignoring math or physics. It's recognizing that the application and understanding of the math and physics is ever-evolving...as we should be as engine builders.

[Stan Weiss]

how long to make a flow test at any given lift ??

How about timed flow testing?

Something along those lines.
I remember jon posting about swirl on a bench and how it takes some time to stabilize as the swirl speeds up and it will flow more because of it, but on real engine it doesn't happen that way. There is a piston in the way. How does it happen on the running engine ? How different is it at 4000 rpm vs 8000 rpm? How much of that swirl is there on the engine ??

How about cases like we've seen where a head flowing less makes more power ?

Or how do you simulate what I seen on my 421 re dyno session ? A head that quits gaining flow at .700" lift with .765" lift on the engine respond like it did to higher ratio rockers that took it too over .800" lift yet that same test has netted no power gain on other engines ?
That 10 average HP from 6000-8500 rpm with most of the gains being over 7000 rpm will sure make the truck pull better, and there is no way to find out without trying on a dyno.

Those are the types of things you can't simulate on a flow bench.
And none of the sims I've used would have predicted that power gain. I'm sure there are high end sims that will and maybe I should look into them.

So what's a better flow test is the question ?

Randy

Just what kind of dyno testing do you do? Are you using a inertia type dyno which lets the engine have a variable acceleration rate like it will on a drag strip or the standard 300 or 600 rpm per second tests?

Stan

[steve cowan]

I wonder if people on construction forums talk about the best way to build something using the industry stnd measurements and lingo or if they just turn everything into arguing that 1 foot really isn't a foot?

It is just strange that the few who want to start this argument year after year after year after year use the same tools and industry standards when developing their engines as the rest of us.

When I started, the industry standard for flow bench pressure was 3". Then it went to 10". Then to 25". Now it's 28"
If no one questioned the industry standards, we would still be using 3".

Do you know of any published data on a cylinder head breakthrough from flowing at a higher depression? I know Darin talks about t for an Indy head, it would be interesting to read what people have found.

I know DV talked about wanting to see a highly pressurized exhaust flow bench but it never came to pass.

I think size, velocity/air speed is more telling but I bet there will never be a consensus on whats best there either

i read some time ago that Lee Shepard and Warren Johnson were testing at higher than the 28'' industry standard back in the early days in there R and D.
Bill mentioned 100'' measured cylinder pressure in race engine.
why wouldn't you want to flow at the highest depression possible.
it might sound smooth and quiet at 10'',15'',20,28''
and go crazy after that and you wont know.
even with my limited experience i am not convinced that having to convert 10'' to 28'' etc really tells the story.
no argument intended just my thoughts.
i have worked highrise construction for 30 years,i didnt know there was construction forums-might look into that

[GARY C]

When I started, the industry standard for flow bench pressure was 3". Then it went to 10". Then to 25". Now it's 28"
If no one questioned the industry standards, we would still be using 3".

Do you know of any published data on a cylinder head breakthrough from flowing at a higher depression? I know Darin talks about t for an Indy head, it would be interesting to read what people have found.

I know DV talked about wanting to see a highly pressurized exhaust flow bench but it never came to pass.

I think size, velocity/air speed is more telling but I bet there will never be a consensus on whats best there either

i read some time ago that Lee Shepard and Warren Johnson were testing at higher than the 28'' industry standard back in the early days in there R and D.
Bill mentioned 100'' measured cylinder pressure in race engine.
why wouldn't you want to flow at the highest depression possible.
it might sound smooth and quiet at 10'',15'',20,28''
and go crazy after that and you wont know.
even with my limited experience i am not convinced that having to convert 10'' to 28'' etc really tells the story.
no argument intended just my thoughts.
i have worked highrise construction for 30 years,i didnt know there was construction forums-might look into that

I made that last part up but I bet there is.

I look at a bench like a dyno, it's good for comparing the changes you made to the thing your changing and then try to build a data base off of what you learn, I think it would be great if everyone could afford a 100" bench but until then we are stuck trying to learn with what we have and it seems few can interpret what is being seen there.

I think time and experience with the tool is probably more important than the tool itself.

[CGT]

I look at a bench like a dyno,

Me too, some people use and own them(benches and dynos) and don't know shit about them or how they work, others make use of them as good tools...others somewhere in between.
Trying to continually learn how they work can make you aware of their shortcomings.. Frequency of use isn't a guarantee either. Some people run miles everyday but will never be elite marathoners.

I think time and experience with the tool is probably more important than the tool itself.

Do you consider it a beginners tool, an intermediate tool, or an advanced tool for development?...or all of the above?

[CGT]

Steve...your thread may or may not be your thread anymore

[GARY C]

I wonder if people on construction forums talk about the best way to build something using the industry stnd measurements and lingo or if they just turn everything into arguing that 1 foot really isn't a foot?

It is just strange that the few who want to start this argument year after year after year after year use the same tools and industry standards when developing their engines as the rest of us.

I see no argument here over the need to have standards, they are in place and are useful ,somewhat necessary in terms of being able to have conversations with others doing similar things...people talk flow in terms of 28" or cams in terms of .050 duration, these give you a quick glimpse into what your dealing with although they may mean a lot or not much at all...

Its the application of that data, and what it means to you, whether based on history, software etc.. that seems to get people excited. I think sims and software are tools, more useful to some than others, how useful may depend on where your "at" in the grand scheme of things. Going outside of a sim isn't ignoring math or physics. It's recognizing that the application and understanding of the math and physics is ever-evolving...as we should be as engine builders.

I don't think anyone would disagree with, it just seems more productive in the context of this setting to share port size, cross section, airspeed, flow and a picture for example if possible so those learning have an idea of what they are trying to achieve and Chad seems to be one of the few willing to do that anymore even though he knows he will be ridiculed for anything he posts.

[GARY C]

I look at a bench like a dyno,

Me too, some people use and own them(benches and dynos) and don't know shit about them or how they work, others make use of them as good tools...others somewhere in between.
Trying to continually learn how they work can make you aware of their shortcomings.. Frequency of use isn't a guarantee either. Some people run miles everyday but will never be elite marathoners.

I think time and experience with the tool is probably more important than the tool itself.

Do you consider it a beginners tool, an intermediate tool, or an advanced tool for development?...or all of the above?

Depends on how far one takes the data, how many advanced head developers don't use one?

[GARY C]

i think Randy's question -how much cfm do you need in a running engine??
was valid as different depressions have not really been mentioned here,please bare with me as i am not the smartest person around.
some calculations i made (only rough )
383 ci
cfm demand at peak piston speed approx 76deg atdc
5000rpm-234
5500rpm-257
6000rpm-281
6500rpm-304
7000rpm-327
7500rpm-351
8000rpm-374
i would assume that demand varies to piston position and rpm through the range.
port velocity will vary through rpm/valve lift sequence etc
if port is stable and airspeeds stable port in theory should keep flowing till choke ??
flowbench flow air one way at a time-engine dont but i think we would like it to flow one way from intake to cylinder.
i wont put all the numbers up but i played around with a set of sportsman 2 heads a while back.
198cc as cast
227cfm@.600''@28'' turbulent @ 0.400''
velocity
pinch-240ft/sec
floor-345ft/sec
apex ssr-245ft/sec
these heads had a 3 angle valve job previously and at 86% throat
i set pinch to 2.3''
blended throat to 87%
narrowed guide boss
did not touch SSR just blended through port and polished apex of SSR
so lifts above 0.500'' it picked up 12% cfm
260cfm @ 0.600''@ 28''
velocity
pinch 285ft/sec
floor 330ft/sec
apex 330ft/sec
port was smooth through the lift range and reckecked at 202cc
so then i tested at 35'' depression
wont bother with all the numbers
500''-277
550''-285
600''-288
650''-291
700''-296
velocity
pinch 310
floor 420
apex ssr 398
what i am trying to say is flow and velocity increase with depression,how much depression does running engine have at peak demand ??
i have read Larry Meaux early readings about sonic choke
can a engine choke from to much cfm??
could be a stupid question (maybe)

CGT is correct, we stole Steve thread. Maybe this will get back to what he is doing.

[SpeierRacingHeads]

I wonder if people on construction forums talk about the best way to build something using the industry stnd measurements and lingo or if they just turn everything into arguing that 1 foot really isn't a foot?

It is just strange that the few who want to start this argument year after year after year after year use the same tools and industry standards when developing their engines as the rest of us.

I see no argument here over the need to have standards, they are in place and are useful ,somewhat necessary in terms of being able to have conversations with others doing similar things...people talk flow in terms of 28" or cams in terms of .050 duration, these give you a quick glimpse into what your dealing with although they may mean a lot or not much at all...

Its the application of that data, and what it means to you, whether based on history, software etc.. that seems to get people excited. I think sims and software are tools, more useful to some than others, how useful may depend on where your "at" in the grand scheme of things. Going outside of a sim isn't ignoring math or physics. It's recognizing that the application and understanding of the math and physics is ever-evolving...as we should be as engine builders.

I don't think anyone would disagree with, it just seems more productive in the context of this setting to share port size, cross section, airspeed, flow and a picture for example if possible so those learning have an idea of what they are trying to achieve and Chad seems to be one of the few willing to do that anymore even though he knows he will be ridiculed for anything he posts.

This is a business of being judged by your peers. This is a business of who you are doing work for. This is a business of TRACK results. A dyno is a tool, and even they don't match all the time! And certainty not one that is the end all! However some seem to think that about as much as anything. As far as myself, been doing it everyday for the last 14 years and still doing it. I'll share with anyone. For those that don't agree, I'm simply not talking to them. For those that don't agree and continually talk shit, just means they are scared I might know something they don't.

My only worries are my customers.

I use to worry about defending myself, but that is leaving me in my older age. Now it's just about taking my vision/talents and making it the best possible. Hanging more track records on my wall. Meeting the right people. And being a part of a dying art.

[CGT]

Depends on how far one takes the data, how many advanced head developers don't use one?

Well i'm sure that varies but I guess my question was semi-rhetorical. I had a good conversation with Matt Bieneman(MBE cylinder heads) recently, he answered more questions of mine than I thought he would. I got the impression it wasn't their go to development tool but was used as more of a "diagnostic" tool. Guys like that established what flows good a long time ago...

[GARY C]

Depends on how far one takes the data, how many advanced head developers don't use one?

Well i'm sure that varies but I guess my question was semi-rhetorical. I had a good conversation with Matt Bieneman(MBE cylinder heads) recently, he answered more questions of mine than I thought he would. I got the impression it wasn't their go to development tool but was used as more of a "diagnostic" tool. Guys like that established what flows good a long time ago...

What if they didn't have a bench how would they diagnose what they are developing and would they be as advanced in their development having never had one to establish what flow is good to begin with?

My guess is they wouldn't even be in business.

One of the most out of the box developments I have seen in a 23 degree head in all my time was Self Racing's Port Intruder that involved countless hours of bench, dyno and track but I am not sure how many are able to duplicate the results they can get out of it and I am sure others have used a different port size and shape to mach their performance.

If someone can develop a head with a leaf blower then more power to them although they will be told they are doing it wrong.

Using a tool or not using a tool doesn't make one better than the other but it may speed up the task at hand.

[digger]

Gary, its not that flow benches are useless they have their place but you are never going to get the final answer off of one. the operating conditions on the engine are too different to get 100% correlation. this applies to all tools as well they help limit testing but do not eliminate the need completely and never will

[GARY C]

Gary, its not that flow benches are useless they have their place but you are never going to get the final answer off of one. the operating conditions on the engine are too different to get 100% correlation. this applies to all tools as well they help limit testing but do not eliminate the need completely and never will

Yes this I know.