Hmmmm, thanks for the tip guys. Maybe time for a slight re-design.
4bbl carbs are rated at 1.5 in/hg (20.3 in/H2O) and 2 bbls are rated at 3in/hg.
Formula to standardize tests?
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by rx7carl » Tue Feb 17, 2004 1:09 pm
Nope, but thats the point of starting this thread. I am under the impression that the calculated numbers will vary based on local ambient conditions. And bringing the bench into the house to keep standard conditions wont go over well with the wife.
- rx7carl
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by 100-1076808581 » Fri Feb 20, 2004 3:57 pm
[color=#000000]I am a newbie to this flowbench stuff so if my questions seem stupid please bear with me. I am also a computer programmer (C++ for Windows & Linux) and therefore know how easy calibration for altitude, weather and other variables should be.
I found a sheet in an old SuperFlow book that stated that a test plate with an orifice of exactly 1 square inch should flow 106.9 CFM at a 15
I found a sheet in an old SuperFlow book that stated that a test plate with an orifice of exactly 1 square inch should flow 106.9 CFM at a 15
- 100-1076808581
by Mouse » Fri Feb 20, 2004 9:09 pm
Kim,
That must be for a streamlined orifice. I don't know what defines a streamlined orifice, but a sharp edge orifice has a very predictable discharge coeffiency.
Someone sent me a copy of that page a while ago, and while I tried to make a streamlined orifice, it caused so much turbulence and pulsing in my system I could not get a good reading. With sharp edge orifices, my readings only bounce a few tenths of a cfm.
Oh, by the way, I figure that 1 square inch area equals 1.129" diameter.
About flow numbers that don't match puplished numbers: I have been collecting flow numbers for quite a while now, and I can assure you that there is always very large differences (at least on SBF heads) in flow numbers even using the same brand bench (usually SF600). Aftermarket numbers are very hard to match because they will usually flow 100 sets of heads and publish only the best numbers. A lot has to do with how the operator reads a manometer. If it is bouncing, some will take the lowest reading, others the highest while still others will try to read an average.
John
That must be for a streamlined orifice. I don't know what defines a streamlined orifice, but a sharp edge orifice has a very predictable discharge coeffiency.
Someone sent me a copy of that page a while ago, and while I tried to make a streamlined orifice, it caused so much turbulence and pulsing in my system I could not get a good reading. With sharp edge orifices, my readings only bounce a few tenths of a cfm.
Oh, by the way, I figure that 1 square inch area equals 1.129" diameter.
About flow numbers that don't match puplished numbers: I have been collecting flow numbers for quite a while now, and I can assure you that there is always very large differences (at least on SBF heads) in flow numbers even using the same brand bench (usually SF600). Aftermarket numbers are very hard to match because they will usually flow 100 sets of heads and publish only the best numbers. A lot has to do with how the operator reads a manometer. If it is bouncing, some will take the lowest reading, others the highest while still others will try to read an average.
John
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