air flow #s ?

[Jeff Lee]

all sound mathematical reasoning. But don't forget the first law...
Garbage in, garbage out!

[Adger Smith]

And don't forget there are other things at play where the laws of physiscs don't apply. Kevin, On the Speed Talk Forum We did a pass around of a calibrated flow plate. Some of the guys were at The Engine Masters Challenge and spawned the idea. It is interesting the different #'s that were obtained all across the country. Most of the guys know a lot about what is going on & why.
I can tell you that a guy wanting to "sell" is more apt to use the 25 number than the 28. There are many reasons for that besides a big #. It is a shame that this industry has the "big is better mentality".
I've had ports that are very bad have better numbers at 25 than 36 or 28. Simply because of twist and turns that cause separation and swirl. You can't even tell the ports are bad until you step up the depression. (also steps up the FPM of the air flow) I don't think there is any number that can be considered the "Best" flow depression.
Hey, What is the best wine? Depends on the meal, doesn't it??
BTW: Just look at all the different numbers these carb salesmen use to sell their work. In the real world they mean nothing with the high FPM flow through a carb.
Yep, It's My .02 :~)

[Dwight Southerland]

Nobody has mentioned the quality of the air. Even with accepted procedures for correcting to STP, I have found significant differences in my own shop depending on the time of the year and even from which direction the current weather front has come from.

[Alan Roehrich]

Originally Posted by Dwight Southerland

Nobody has mentioned the quality of the air. Even with accepted procedures for correcting to STP, I have found significant differences in my own shop depending on the time of the year and even from which direction the current weather front has come from.

While I did not mention it specifically, it was what I was alluding to when I mentioned locations and conditions.

[Adger Smith]

Wow! Someone finally brought it up.. Thanks Dwight.... Fall fronts are different from Spring fronts. You may have the same DA's, but you can get the same DA's with a totally different set of air/weather readings. If the program is not set up(written) to allow for this, you will see variations in the final #'s. That is just one of those things as well as the human element that keeps numbers from repeating exactly or being exactly the same. Then I might add the computer differences. Not all the same Algorithms are used to do the different programs used for correction. Small differences are there yet the Laws of Physics are not cheated and are still in place.

[SSDiv6]

Originally Posted by Adger Smith

Wow! Someone finally brought it up.. Thanks Dwight.... Fall fronts are different from Spring fronts. You may have the same DA's, but you can get the same DA's with a totally different set of air/weather readings. If the program is not set up(written) to allow for this, you will see variations in the final #'s. That is just one of those things as well as the human element that keeps numbers from repeating exactly or being exactly the same. Then I might add the computer differences. Not all the same Algorithms are used to do the different programs used for correction. Small differences are there yet the Laws of Physics are not cheated and are still in place.

Yep; there is a lot involved to get the right numbers and it can get a bit complex many times when you start to apply CFD concepts.

Just attended a class on Computational Fluid Dynamics (CFD) sponsored by NASA and it confirms the many things that can affect flow numbers.
Had an interesting discussion with the instructor on how temperatures can effect the final numbers and behavior. Also discussed the importance about velocity and its effects on obtaining real CFM numbers..

[Adger Smith]

spSS6 I was going to say that NASA was probably the only group that really get it and do it right. The real problem is we (the avg guy) can't afford to buy the resources they have. We have to use the systems/programs made available to us at the affordable price. (And some not so affordable)
In a perfect world what Kevin is saying could and should happen, but we don't live in that kind of world. I'm not saying everthing is wrong. I am saying there are those among us that try to make things (corrected numbers) closer to right or as close to right as they can be. Then there are others (salesmen that usually don't understand) that use the numbers just for a sales pitch. I'm sure it's tough to be a customer and wade through all of it.

BTY: There are two books I keep on my headboard for those non sleeping late night reads.
Books from my college Fluid Dynamics & Applied Physics

[SSDiv6]

Originally Posted by Adger Smith

spSS6 I was going to say that NASA was probably the only group that really get it and do it right. The real problem is we (the avg guy) can't afford to buy the resources they have. We have to use the systems/programs made available to us at the affordable price. (And some not so affordable)
In a perfect world what Kevin is saying could and should happen, but we don't live in that kind of world. I'm not saying everthing is wrong. I am saying there are those among us that try to make things (corrected numbers) closer to right or as close to right as they can be. Then there are others (salesmen that usually don't understand) that use the numbers just for a sales pitch. I'm sure it's tough to be a customer and wade through all of it.

BTY: There are two books I keep on my headboard for those non sleeping late night reads.
Books from my college Fluid Dynamics & Applied Physics

Adger,
NASA has these CFD seminars for free on the web several times a year.
They are called "Webinars" and they are taught by a company named COMSOL and sponsored by NASA.
Next time I get an invite to attend another CFD Webinar, I will post it here so anyone interested can sign up and attend...and it is free.

[Adger Smith]

Great! Thanks. Nice to know that . I'll never be too old to learn!

[Adger Smith]

Gosh, Those guys are really into the training, even worldwide..
Did a Google on them. Interesting!! I might have to dig back into my 40 year old College... LOL!