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Old 11-27-2005, 04:44   #1 (permalink)
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Alloy Heads, the facts

Hi Guys

I have read all the threads & magazine articles.

Does any one have any independant results on the flow figures on either of the current crop of super alloy heads available for clevelands?

Has anyone directly compared the CHI 218'S against AFD 4V'S

From the manufactures data they seem very close.

PLease only certified flow sheets, so we can make an informed purchasing decision.
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Old 11-27-2005, 05:08   #2 (permalink)
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Re: Alloy Heads, the facts

Quote:
Originally Posted by BAGTHO
Hi Guys

I have read all the threads & magazine articles.

Does any one have any independant results on the flow figures on either of the current crop of super alloy heads available for clevelands?

Has anyone directly compared the CHI 218'S against AFD 4V'S

From the manufactures data they seem very close.

PLease only certified flow sheets, so we can make an informed purchasing decision.
Here's 2 independant tests.
Both had 2.190" inlets.
The CHI's were cleaned up in the ports & chambers.
The AFD's are mine. The original "out of the box" flow figures were much worse (585hp @ .600" lift). We changed inlet valve seat angles & picked up 72hp!
All flow figures at 7" flow are corrected to 10" flow.
I have a flow conversion chart if anyone is interested. It converts any inches of flow to another flow e.g. 7" flow to 28" flow.
Cheers, from Mal.
PS: We're still experimenting on the exhaust flow on my AFD's.
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File Type: jpg afd flow chart.jpg (118.8 KB, 97 views)
File Type: jpg chi flow chart.jpg (109.9 KB, 120 views)
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Old 11-27-2005, 06:15   #3 (permalink)
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Re: Alloy Heads, the facts

I'm pretty sure next month the CHI 4v's will be released. Figures will surprise most
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Old 11-27-2005, 10:01   #4 (permalink)
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Re: Alloy Heads, the facts

Quote:
Originally Posted by tufLTD
Here's 2 independant tests.
Both had 2.190" inlets.
The CHI's were cleaned up in the ports & chambers.
The AFD's are mine. The original "out of the box" flow figures were much worse (585hp @ .600" lift). We changed inlet valve seat angles & picked up 72hp!
All flow figures at 7" flow are corrected to 10" flow.
I have a flow conversion chart if anyone is interested. It converts any inches of flow to another flow e.g. 7" flow to 28" flow.
Cheers, from Mal.
PS: We're still experimenting on the exhaust flow on my AFD's.
Whoever produced the chart should have normalized the results to a single pressure rate. Also, it would have been nice to have the .050" lift flow values included, as this would help to understand how well the port works.

Also, it is "not right" to produce a set of data without stating the units of measure, even if they can be reasonably assumed...as is demonstrated in the "pressure" row. We can assume that it is in inches of water. As for conversion, it is a fairly basic calculation when one value is known. What is not known, but again assumed is that the water temperature was at 20*C, which is rarely the case on most of the flow benches that I've seen. Another reason for normalizing the data is in producing "corrected" results. These charts do nothing to suggest that the results were corrected, though it is assumed that someone producing so much data would certainly have corrected the results, but one never knows for sure without at least seeing it on the sheet.

The conversion chart is not needed if we can assume that the data is corrected. The maximum flow result in CFM of the CHI head intake port is 352.76 while the maximum flow result in CFM of the AFD head intake port is 358.94 (both at 28" water @ 20*C). Considering that my 20+ year old technology A3 alloy heads flowed 357 CFM on the intake, I'd say that we're seeing the direction of the technology move more into a "flow quality" rather than just "flow quantity," which is what is truly described in a flow chart. What we need to see from a flow chart is flow quality and that is relatively unobtainable with current flow bench products and equally unobtainable with the charted results.


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Old 11-28-2005, 00:34   #5 (permalink)
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Re: Alloy Heads, the facts

Quote:
Originally Posted by davis
Whoever produced the chart should have normalized the results to a single pressure rate. Also, it would have been nice to have the .050" lift flow values included, as this would help to understand how well the port works.

Also, it is "not right" to produce a set of data without stating the units of measure, even if they can be reasonably assumed...as is demonstrated in the "pressure" row. We can assume that it is in inches of water. As for conversion, it is a fairly basic calculation when one value is known. What is not known, but again assumed is that the water temperature was at 20*C, which is rarely the case on most of the flow benches that I've seen. Another reason for normalizing the data is in producing "corrected" results. These charts do nothing to suggest that the results were corrected, though it is assumed that someone producing so much data would certainly have corrected the results, but one never knows for sure without at least seeing it on the sheet.

The conversion chart is not needed if we can assume that the data is corrected. The maximum flow result in CFM of the CHI head intake port is 352.76 while the maximum flow result in CFM of the AFD head intake port is 358.94 (both at 28" water @ 20*C). Considering that my 20+ year old technology A3 alloy heads flowed 357 CFM on the intake, I'd say that we're seeing the direction of the technology move more into a "flow quality" rather than just "flow quantity," which is what is truly described in a flow chart. What we need to see from a flow chart is flow quality and that is relatively unobtainable with current flow bench products and equally unobtainable with the charted results.


:davis:
I think the reason they use lower flow rates is that there aren't many flow benches here in Oz big enough to flow large cfm at 28''. Quite a few people I've spoken to confirm this. Not that it really matters. As you say, it's easy enough to convert flow rates.
You mention that you can only assume it's measured in inches of water. Is there any other measurement? I thought all flow benches measured in inches of water.
And, yes, as I wrote, the 7" results are corrected to 10". I know the charts don't say this, but I can assure you that it is the case.
The reason I posted the charts was for an independant comparison between CHI & AFD, regardless of what flow rates were used on these charts.
I've attached a flow conversion chart for anyone interested.
Cheers, from Mal.
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Old 11-28-2005, 00:51   #6 (permalink)
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Re: Alloy Heads, the facts

Quote:
Originally Posted by davis
"flow quality" rather than just "flow quantity,":davis:
The hardest thing to explain is this to garage racers that listen to so called porters! Try telling someone exactly why port tongues work in 4v's! Ultimate flow numbers are only a guide to the potential hp! Just look at trick & mansweto(?) 2v 393 they only flow 550 odd hp maybe less and make 601hp
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Old 11-28-2005, 01:15   #7 (permalink)
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Re: Alloy Heads, the facts

You must decide what the engine will be used for, if all out flow is the go then you would look at yates or blue thunder a3 heads etc, you dont get a full weight xy falcon into low 9's with any thing much less, on a street car, weekend racer i like the look of the chi 218cc when used with the matching component's eg cam, comp ratio but i would not knock back a set of afd's for the right money or new edelbrocks
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Old 11-28-2005, 06:18   #8 (permalink)
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Re: Alloy Heads, the facts

Quote:
Originally Posted by tufLTD
I think the reason they use lower flow rates is that there aren't many flow benches here in Oz big enough to flow large cfm at 28''. Quite a few people I've spoken to confirm this. Not that it really matters. As you say, it's easy enough to convert flow rates.
You mention that you can only assume it's measured in inches of water. Is there any other measurement? I thought all flow benches measured in inches of water.
And, yes, as I wrote, the 7" results are corrected to 10". I know the charts don't say this, but I can assure you that it is the case.
The reason I posted the charts was for an independant comparison between CHI & AFD, regardless of what flow rates were used on these charts.
I've attached a flow conversion chart for anyone interested.
Cheers, from Mal.
Well, of course, they can't flow enough at higher pressures. My point was that the quality of the product (the data chart) is lacking due to the inadequacies of the data. Take your lastest flow chart conversion table as yet another example of inadequate representations. The conversion table does not indicate what operation is performed to achieve the conversion! It is obvious to someone who knows how to convert pressures from any number of standards, say in bars, pascals, atomspheres or inches of mercury. Computerized flow benches can easily adjust output to any of these and more known constants based on correction figures entered before the data acquisition phase. In other words, why hand a human a sheet of paper and a conversion chart so that s/he must then come up with the corrected and normalized results without so much as even the mention of the mathematical conversion operation required? To me, that is simply poor publishing.

I think that I got the idea behind why you posted the charts. I'm not trying to insult you for doing it, either. I'm just saying that the quality of the data and the presentation of the charts is lacking. It is like looking at a very old map of the world, in some respects. While perhaps very intriguing and certainly worthy of some extended review, they're not what you're going to use to plot your course against if you're running an oil tanker, right? The same goes for these charts in terms of the usefulness of the data and its presentation. Perhaps a better choice may have been to convert all of the units to like terms and post the results along with the "raw" representation.

What is most funny about all of it to me is that "mechanism" used in the product. The product is a flow number based on HP, the "like term" that all of the dissimilar unit values are converted to. This HP "value" is the "component" of the product that is being sold to you Aussies and New Zealanders (I wouldn't want to say Kiwis in case that may insult anyone), it appears. A very slight modification of the formula used to produce the "HP" value, and suddenly, your flow bench is much better than the bloke's down the street!

What is more stupidly funny is that the "HP" selling point shows exhaust and intake for the same port to make different amounts of HP. What is more stupid than that? With this intake port your engine will make 600-blah-blah horsepower, mate...but, too bad it will only make 300-blah-blah horsepower with that bloody exhaust port! It also raises the question of what method was used to convert some flow number into some HP number, which is clearly not readily apparent from a quick glance at the non-normalized data. It would be a fun math problem should anyone care to spend one's time playing math games, but for someone who wants to immediately see the data set the only choice is the graph component of the product. And, it is that graph, which you say is normalized to 10" water, not the data points that produced the graph.


Look Mel, I'm not trying to get down on you in anyway at all. I'm just saying that the usefulness of the product is questionable at best. That isn't to say that it isn't entirely accurate or even 100% truthfully corrected. What I'm saying is that the presentation method used to produce the product and the lack of certain data elements open it up to all kinds of speculation about data integrity and overall correctness for any applicable use of the data. If I were a detective and this data were a suspect, I would have a "funny feeling" about this suspect after the interrogation (reviewing the data). A better quality product would remove the funny feeling from the outset by being more complete, normalized and clearer by stating the correctedness of it. The conversion chart, for example, would indicate that the conversion from X to Y would require a multiplication of X by the number found at the intersection of the X and Y in the table. That's all I'm trying to say in what is probably the most longwinded way.

If this data source is something that you dug up from the web somewhere, I'd try to find better sources. If this data source is a product handed to you by a flow bench operator, I'd try to encourage that person to produce a better representation of the corrected and normalized data. If this is a product that you've paid for, I'd demand better quality simply because it is about as worthwhile as marketing hype in a comparison of Coke to Pepsi--as presented. It is kind of like the ricer with the 4 different colors of primer and the unpainted fiberglass hood. Kind of difficult to respect it and who cares if it runs fast?

Additionally, the conversion chart is interesting. To convert from 7" water to 28" of water you multiply by 2. 7:28 as 1:2?

What it is not telling you is that it is calculating for CFM. Yet another little tidbid of useful information left off of the chart.


A flow bench can be simply described as shown in the following image:



Where P1 is the pressure before the orifice, the part being "flowed" is the orifice and P2 is the pressure after flowing through the orifice. Due to the inconsistency of the part shape, we can not easily describe the frictional losses except as a component of the re******t flow decrease in pressure from P1 to P2.

However, in most flow benches, the flow direction is similar to the photo if turned 90* clockwise, or from top to bottom. However, the higher pressure is not at P1, it is at P2, which is the source of the low pressure area. Then delta P is P2 - P1, and not P1 - P2.

If we assume the differences and substitute the Ps...we get:



Then if we want to get rid of the velocities and calculate for volumetric flow "Q":



...and solve for Q:



...and now we must solve for the discharge coefficient, since there is going to be some turbulence in the port and viscosity of the air:



...and then solve for the flow coefficient:



...assuming that for A0, we measured the volume of the port, we can calculate the true volumetric flow rate Q:



...and because we undoubtedly have differing inlet and outlet orifice dimensions:




...of course, sometimes too much information is just as bad as not enough! <grin>


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Old 11-28-2005, 13:41   #9 (permalink)
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Re: Alloy Heads, the facts

Ouch, my head hurts Davis.
Are you trying to baffle me with brilliance or bullshit? Either way, it worked!
No really, I appreciate you going so in-depth but how many flow tests (either in Oz or USA) get that technical? Maybe they should, it would give us a better overall view for comparisons.
As for the HP quoted by the makers of these heads, it's dubious at best.
My heads originally flowed a lousy 585hp @ .600" lift. A long way from the 680hp 'out-of-the-box' figures advertised.
I'm interested in your thoughts on exhaust port flow. I know an exhaust will never flow anywhere near the cfm of an inlet but I've been told to aim for a 70 - 75% inlet/exhaust ratio (especially with nitrous). That would mean that I need to get my exhausts flowing up around 450hp. Do those figures sound right to you?
Cheers, from Mal.
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Old 11-28-2005, 15:37   #10 (permalink)
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Re: Alloy Heads, the facts

A few blokes in the US have flow tested out of the box and came up with very very close to out of the box figures. Weird huh?
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