Pinch point debate 2

[rookie]

Back on topic, I will refrain from getting personal.
Part 1... viewtopic.php?f=1&t=35232

[Warp Speed]

Back on topic, I will refrain from getting personal.
Part 1... viewtopic.php?f=1&t=35232

Hahahahaha...................Sure you will, as long as nobody disagrees with you or DV. LOL

[SchmidtMotorWorks]

Some very respectable companies that make 23°CNC stuff relies the port shape on the hands of a good , experienced head porter and his flow bench with pitot tubes. Sometimes wet flow.

Then after 1-200 hours developing the port by hand, it is digitalized and the CNCs can duplicate them.

IMO the humble flow bench , although not reproducing exactly what will happen in the running engine still is the most accurate connection to what is happening into the port and power production.

On what basis do you form that opinion if you have no experience with CFD?

The softwares indeed can calculate billions of parameters per second but how to apply what its showing without a way to measure the changes?

That is one of the main benefits of CFD, it enables you the see the pressure, veleocity, vorticity etc of moving air (which is invisible to the eye) and can be done in places that the eye cannot see.

Schmidt ,I'd be very interested to know how the top teams develop their head ports nowadays....

They just have a digital model, run it through simulators, watch where the flow is turbulent, too fast, etc, change the digital model , simulate again, call it good, CNC mill the head and dyno the engine?

That is basically it, digital modeling, simulation, optimization and manufacturing is the most cost effective way to make things today.

http://www.autofieldguide.com/articles/ ... ble-engine

There was a comprehensive computer-aided and physical testing regimen for the Gen 5 engine development. This included steady-state airflow assessments, 3D computation fluid dynamics, airflow bench testing, one dimensional, engine cycle simulation, geometric flame propagation analysis, 3D mixing and combustion analysis, single and multi-cylinder combustion testing, and vehicle-level performance and fuel economy analysis. Thirty analysts worked digitally on the engine development program, literally years before the first physical model was produced. They used both commercially available CAE/CAD software as well as specially developed code. It is estimated that there were more than 10-million hours of computational analysis for the engine development.

Don't confuse the 10-million hours with human hours, it is computer simulation hours. One person runs many simulations at the same time and the computers run 24-7. No way that a person can make prototypes, test them and keep up.

[SchmidtMotorWorks]

If someone wants to scan a port with pinch in it, I'll show how it can be examined with CAD and CFD.
Much better if you can scan the manifold too.

[user-9274568]

This process get's done to every cylinder head I develop by hand and have digitized and cut.

It's nothing new.

Let me ask you a question. How do we "assume" what the CFD is telling us is correct? Wasn't it introduced by human element? Why can't that be processed with a big brain? You seem to think people have completely abandoned brain cells and rely on a generated source as gospel.

While I agree that any available resource for producing results is a benefit, I have a hard time with someone saying that I as an intelligent human being can only produce cylinder heads because the industry hasn't caught up to technology. That is horseshit. Many small shop have competed with unlimited resourced teams for years. And are we talking fresh sheet design work? If so, your excluding 90% of the members here..

[SchmidtMotorWorks]

This process get's done to every cylinder head I develop by hand and have digitized and cut.

It's nothing new.

Great, if you can send me a scanned port with pinch, a chamber and two runners from a single plane manifold so that we can compare the difference between the pinch being on the short side of the manifold turn or the long side I can make some simulations and you can see for yourself if they are informative. Scanned castings will be fine if you don't want to release private data.

Let me ask you a question. How do we "assume" what the CFD is telling us is correct? Wasn't it introduced by human element? Why can't that be processed with a big brain? You seem to think people have completely abandoned brain cells and rely on a generated source as gospel.

Thats the great thing about adopting the technology 10+ years after the aerospace and automotive companies have spent $100s of millions to have the software developed, validated and refined. It's like drafting in NASCAR, you get to go fast withut putting out as much effort as the leaders did.

The technology enabled us to land on Mars on the 1st try. 7 minutes of terror
http://www.jpl.nasa.gov/video/index.php?id=1090

It isn't like it was in the 70's where you had to develop your own software, only the very most unusual problems require new code and even that is usually built on top of exisitng commercial code.

While I agree that any available resource for producing results is a benefit, I have a hard time with someone saying that I as an intelligent human being can only produce cylinder heads because the industry hasn't caught up to technology. That is horseshit. Many small shop have competed with unlimited resourced teams for years. And are we talking fresh sheet design work? If so, your excluding 90% of the members here..

Look at the Gen 5 GM engine, it isn't exactly an original design, it is lot's of small refinements. They are all about getting the best result done for the least time and money spent. They were asking for the techonologies needed in the software to make this way of working possible for as long as I have been working in the field. What I am trying to get across is that now these tools are readily availabale to anyone that wants to use them thanks to those that paid for their development.
In other words, think of it like mobile phones, in 1984 a mobile phone was an expensive heavy thing to carry around. Today, most people can't imagine living without one. CAD/CAM/CAE has made similar progress in usabilty.

Maybe taking it out of context, think of CFD like an MRI or CAT Scan, or other medical test. You might have the best most experienced doctor in the world but they succeed by using the latest technologies to see things inside your body that are not availabale to thier eyes.

If you have cancer, do you want the doctor that says "trust me I know what I'm doing, I don't need any MRI to see where the cancer is" or do you want the guy to have the scans run so he knows where the cancer is?

[user-9274568]

But what does the automotive industry know about fluid dynamics that I should put my trust in it? They spent millions, so it has to be correct?

How does that differ from a guy using his brain, his pitot, his flowbench, and producing a cylinder head that runs faster and quicker than any other pass in history? How does that differ than making a pass and letting the engine tell us what it wants? You admit that IT CAN BE DONE, and I'll give you your props. You admit that a solid data base can net positive results, and you can have your props.

You don't think I can tell which way the air goes, what the velocity is, and what needs to be done to a pinch depending which way the port goes with my available resources? really?

Why is it GM keeps putting more cross section on engines and they make more torque?

[SchmidtMotorWorks]

But what does the automotive industry know about fluid dynamics that I should put my trust in it? They spent millions, so it has to be correct?

I don't understand your question, the software models the physics without any concern for whether it is a car or an airplane.

Yes, if they spend $millions on validation (as they have) we know how accurate it is.

How does that differ from a guy using his brain, his pitot, his flowbench, and producing a cylinder head that runs faster and quicker than any other pass in history? How does that differ than making a pass and letting the engine tell us what it wants? You admit that IT CAN BE DONE, and I'll give you your props. You admit that a solid data base can net positive results, and you can have your props.

It differs in several ways, for someone in business the advanced technologies enable you to quantify and duplicate succeses better.
Better insights with higher fidelity tools enable us to get to more optimal answers in fewer tries and being digital affords us the opportunity to try things that we may not have the time or money to do on physical parts.

You don't think I can tell which way the air goes, what the velocity is, and what needs to be done to a pinch depending which way the port goes with my available resources? really?

Even with the 1,000s of parts that I have designed there is almost always some element of surprise or discovery in every simulation that I do.

[user-9274568]

So you can't admit that you can produce cylinder heads that can dominate without the aid of simulation?

[SchmidtMotorWorks]

So you can't admit that you can produce cylinder heads that can dominate without the aid of simulation?

Given equally talented people exerting the same effort, the person with CFD will have an advantage.

[user-9274568]

So you can't admit that you can produce cylinder heads that can dominate without the aid of simulation?

Given equally talented people exerting the same effort, the person with CFD will have an advantage.

Good to know, another thing I can add to my bullshit file.

Actually this is wrong, I should investigate this more before I call bullshit.

So does that mean a guy without CFD that can make more power and run faster that a guy using CFD, must be brilliant? Or just lucky?

[WeingartnerRacing]

Although I think this thread may be going nowhere I would like to add this. Their are several computer models for predicting weather and they still do not get it right. The models where designed by humans having the knowledge they had at the time but they are no way perfect. I think it is arrogant to think that to think that someone can not make or port a set of heads without cfd. People do it all the time. I do think cfd is an advantage but I think talent and hard work can overcome it.

As far as pinch point debate it should be called compromise. You give and take with experiments and data to figure out what is best for what you are doing. I don't like dramatic changes in area and the pinch does just that.

[user-9274568]

^^ I'll agree.

[Stan Weiss]

Chad,
Remember the laws of Physics have been the same since the "Big Bang". The only thing that keeps changing is man's understanding of what those laws real are. Nothing wrong with empirical results, but that is just my opinion.

Stan

[SchmidtMotorWorks]

So you can't admit that you can produce cylinder heads that can dominate without the aid of simulation?

Given equally talented people exerting the same effort, the person with CFD will have an advantage.

Good to know, another thing I can add to my bullshit file.

Actually this is wrong, I should investigate this more before I call bullshit.

So does that mean a guy without CFD that can make more power and run faster that a guy using CFD, must be brilliant? Or just lucky?

Nope, not too many people have gotten into CFD yet so there isn't much to compare to.
The advatage of it is an opportunity that anyone can take or reject.

We all reject things sometimes because they are not familiar to us, when I moved from the Seattle area to California to go racing, I dismissed my older brothers advice to inern at a start-up called Microsoft.