Flow Bench
08-28-2006, 05:54 PM
#1
Staging Lane
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Home Made Flow Bench I was wandering if any one ever heard of making your own flow bench
out of a mass air flow sencor. I'm hand porting some street heads and am gessing i'm not the first one think about this. Could a smog pump make
enough vacume(have it mounted under the chumbustion chamber).
mabe this totally isn't how a flow bench works...............I could be
all wet.
I figure a smaller maf sencor would be needed because of only 1/8 of
the air would be flowing threw it at one time.
later
out of a mass air flow sencor. I'm hand porting some street heads and am gessing i'm not the first one think about this. Could a smog pump make
enough vacume(have it mounted under the chumbustion chamber).
mabe this totally isn't how a flow bench works...............I could be
all wet.
I figure a smaller maf sencor would be needed because of only 1/8 of
the air would be flowing threw it at one time.
later
Last edited by nitsudls1; 08-28-2006 at 09:41 PM.
08-29-2006, 08:55 PM
#3
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more vacume I was just talking to my brother and he clames
I would need more than a smog pump. In fact
he said an aircompressor only flows about 8-12cfm
so you would really need a big vacume pump.
I would need more than a smog pump. In fact
he said an aircompressor only flows about 8-12cfm
so you would really need a big vacume pump.
08-29-2006, 09:45 PM
#4
A smog pump would be way too small. I saw an article in a magazine a bunch of years ago about a home flowbench setup and it used a shop vac for suction. I think that would work with a bigger one, probably 5hp or bigger. The MAF flow meter sounds like a good idea but I don`t have any idea on how to calibrate it.
08-30-2006, 07:06 AM
#5
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I kicked it around using a MAF meter a few years ago. I was leaning towards a leafblower (in 'suck' mode of course). I thought it also might be a way to determine frequency curves on ported MAF meters.
The MAF flows air based on frequency, so you'll need either a frequency counter or an oscilloscope. From there, it's up to you to decide if you want to calibrate the bench to read similar to others (for which you'll also need a pressure sensor in the duct to get it to a standard pressure/vacuum, and apply calculations), or you can just use the bench to measure before/after porting changes and skip trying to calibrate it to other benches.
The MAF flows air based on frequency, so you'll need either a frequency counter or an oscilloscope. From there, it's up to you to decide if you want to calibrate the bench to read similar to others (for which you'll also need a pressure sensor in the duct to get it to a standard pressure/vacuum, and apply calculations), or you can just use the bench to measure before/after porting changes and skip trying to calibrate it to other benches.
08-30-2006, 12:12 PM
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This is one of my slow-rolling projects.
A MAF will give you repeatability but no chain of
calibration to get an absolute accuracy. My plan is to
go with a couple of standard sized orifice plates and
a manometer to get inH2O drops, from which you can
back-figure the flow (volume, not mass flow) using
well proven formulae. I suppose a pair of MAP sensors
and a difference amp would be even cuter but water
is free and vinyl tuing is cheap and the hole saws are
already in the toolbox. Have to correct for air density
somehow, to get volume back to mass flow. Once you
had a MAF worth believing it would be a better way
but the stock MAF cal curves are bogus especially
low down (still air output indicating a nonzero g/sec
in my measurements).
You need a -stout- blower. I found a dust collector at
the Harbor Freight on sale for $79, 4" inlet/outlet and
an alleged 900+ CFM. Maybe that's Chinese CFM like
Chinese horsepower, but what the hell. I also have a
small collection of vacuum cleaner blowers that could
add up to enough. I have used an electric leaf blower
and not been able to max the MAF out. Also tried a
whole-house furnace blower, ditto. May be easier to
work on the pressure side than the suction side.
A MAF will give you repeatability but no chain of
calibration to get an absolute accuracy. My plan is to
go with a couple of standard sized orifice plates and
a manometer to get inH2O drops, from which you can
back-figure the flow (volume, not mass flow) using
well proven formulae. I suppose a pair of MAP sensors
and a difference amp would be even cuter but water
is free and vinyl tuing is cheap and the hole saws are
already in the toolbox. Have to correct for air density
somehow, to get volume back to mass flow. Once you
had a MAF worth believing it would be a better way
but the stock MAF cal curves are bogus especially
low down (still air output indicating a nonzero g/sec
in my measurements).
You need a -stout- blower. I found a dust collector at
the Harbor Freight on sale for $79, 4" inlet/outlet and
an alleged 900+ CFM. Maybe that's Chinese CFM like
Chinese horsepower, but what the hell. I also have a
small collection of vacuum cleaner blowers that could
add up to enough. I have used an electric leaf blower
and not been able to max the MAF out. Also tried a
whole-house furnace blower, ditto. May be easier to
work on the pressure side than the suction side.
