Swapmaster

Has anyone built a flow bench?

I need the inclined monometer percentage scale and incline angle.

Anyone?

I am building a bench and am down to the inclined manometer
and making the orifices. I found a calculator for sharp edge
orifice flows but can't find the incline percentage scale.

I think I may have the incline angle but am not sure if it is correct.

ws6transam

The more shallow the angle, the farther the water will travel for a given pressure differential. It's all geometry on a right triangle.

Your short-side of the triangle represents vertical water. Your long side represents the horizontal length of the guage. Your hypotenuse is the gage itself.

Lets say that you build a guage that can measure eight inches of water across the orifice. Eight inches represents the short-side of the triangle. Lets say that you decide to use a yard stick as your method of graduating lines and that it's 36 inches in length. Your guage will measure eight inches of pressure differential, and spread that differential across 36 inches. Thus, one inch of pressure differential will be reflected by moving the water 36 / 8 = 4 inches down the guage.

Swapmaster

The angle I have from a crude diagram shows a 12" rise and a
28" long scale. So am I correct in thinking it will measure 12"
of water over a 28" scale? With every 2.33" on the scale
reflecting 1" in pressure dif.?

The graduations of this scale are set in percentages from 0 to 100
but they are not evenly spaced. The center of the scale is about
the 75% mark not the 50% mark like I would think it should be.
The 50% mark is about 1/3 of the way up the scale.

You got me one step farther though, now I understand how the
inclined manometer works. Now I need the scale graduations.

When I get this done I will post up pictures and instructions and
ask the mods to add it to the tech archives so anyone can build
one if they wish. It should take less than $100 to build it if you
already have a high flow shop vac.

Swapmaster

I found a site with a graph of the scale graduations but it is too
big to put up on here.

It states.

"An orifice plate has a specific range that it can accurately give flow indication. This is because the differential pressure that the orifice plate creates and the fluid flowing through it does not have a linear relationship. There is a square root relationship between the differential pressure and flow."

Getting closer.
Have any idea what it could be?

Swapmaster

Ok, the scale is 28" long. Divide the scale into 10 parts numbered
from zero to one, ie: 0, .1, .2, .3, .4 etc. Square each number to
get the percentage of air flow. Plot these figures along the scale
then mark off the hundreds and fill in the rest of the scale and
you get a graduated scale based on the non linear flow of an
orifice versus pressure.

Yea right. Well it looks like the scale I'm looking for anyway.

Thanks ws6transam, you pointed me in the proper direction.
It took a heck of alot of searching the net though.

ws6transam

It sounds like you are onto the solution. I am sure that there is a mathematical formula in the CRC guide or other scientific text that describes exactly the relationship of airflow across an orifice and the pressure differential. The pressure differential and airflow are also dependent on the static pressure, which is the reason you also need a manometer that reads from zero to 28 inches of vertical column water. You need to keep your static pressure constant to be able to compare airflow measurements across your port. I believe that the static pressure is measured on the high-side of the orifice, but I'm not sure.

Swapmaster

Yes, when you change orifices for different flow rates you need to
reset your test pressure to your reference point, for automotive
use it is 27.7" which is 1 atmosphere or 1 pound of pressure. This
is accomplished with bleeder valves on the suction side of the
orifice which allow air into the reference side of the chamber to
regulate your reference pressure.

Now it's on to the orifices and the chamber to house them in.
I found a neat little calculator to determine the flow of different
sized orifices so that's out of the way.

Now to devise a chamber for the orifice plates which can be easily
opened to swap the plates yet is air tight.

I am thinking of 2 plastic five gallon buckets?

Bort62

Shame on you Swapmaster, You should know better to Ask Such complicated questions on any TGO board

THat being said, I have no freakin clue what you need

but I do KNow what l33t Mods to do to my 305 TBI to maKe it fast!

Swapmaster

Waaaaaaaaaaaat ????

The inclined Manometer scale is the most technical thing about
a flow bench. But even I figured that one out with a bit of looking
around, if I can do it anybody can do it.

I see no reason why anyone with some decent shop equipment
couldn't build one fairly easily. Even the guages you build yourself
with a couple of yard sticks, some clear vinyl tubing and some
red food dye and water.

Swapmaster

New breakthrough. It's still to coming together.

Actual construction should start soon.

Still getting all my ducks in a row.

The more you learn the easier it gets.

All you have to do is look for it.

It's all out there.

Bort62

If you could only convince 75% of the people on this board of that

87transam5.7tpi

hey swapmaster, once you get that going how much would you charge to flow some heads for me? since you aren't to far from me? I might be doing some this summer, and I don't wanna spend the money to make my own and/or pay $250 to have every port flowed. thanks!

Josh

Swapmaster

Mabe the SEARCH feature of this site should be a more
heavily promoted funtion.

But then we would miss out on all the pissing contests.

I love a good argument.

Swapmaster

87transam5.7tpi,

When I start building this thing I will put up plenty of pics and
what materials I used and where I got them. I will also give
details on how each aspect of it works.

For the $250 it costs to flow a set of heads you can easily build
a bench and do your own, but I could use yours for test subjects
since you are close.

Bort62

Flow benches Suck.

Swapmaster

Shhhhhhh, it's only a dream.

Yes, I know, he didn't really mean to say that.

Ok now, go back to bed, it's not time for your medication yet.

Bort62

Just think about it a sec swap....

Swapmaster

I know that the flow numbers don't mean a damn thing in regards
to how much air will flow through an engine unless you take into
account the effect of adding fuel, the current barometric
pressure, air temp, humidity, cylinder pressures, solar flares,
moon phase, what color of socks you have on and a host of other
factors that play into the equation.

But, the numbers will compare one item to another and give us
the ability to say mine is bigger than YOURS. Which is what this
whole thing is about anyway, RIGHT?

Bigger is stonger is more powerfull is faster, that's what the girls
like anyway, so that's what I'm shooting for.

Swapmaster

And the answer to your next question is NO!

MikeS

If the answer is no, I shouldn't bother asking, but here goes...

Hey swapmaster, how's the progress?

Bort62

Wow 7 month old post, was that really nessicary ?

Swapmaster

Progress has been halted for now. Life got in the way. I still go
over my notes from time to time and would like to restart the
project maybe in the spring.

MikeS

Sure, it was necessary. I thought it was an interesting project and wondered how it was going. Rather than start a new post, why not just continue the old one?

Anyways, Swapmaster,
I hope life got in the way in good ways.

Vader

And to think that I was only curious about what kind of air pump you were planning to use. Got an old Roots blower lying around?

Swapmaster

You don't need to move that much air. Here, check this out.
A strong shop vac will do the job.

Orifice diameters for air flow testing at 5" converted to 28"

For best sensitivity stay within 60% to 95% of an orifices flow value on the
slanted manometer scale.

Pi x Rsq = area
3.1416 x r2 = area

CFM to CFM by change in vacuum
( square root ( new vacuum / origional vacuum )) x CFM = new CFM

To convert flow from 5" to 10" multiply cfm by 1.14
To convert flow from 5" to 28" multiply cfm by 2.37

To convert flow from 10" to 5" multiply cfm by 0.707
To convert flow from 10" to 28" multiply cfm by 1.67

To convert flow from 28" to 5" multiply cfm by 0.422
To convert flow from 28" to 10" multiply cfm by 0.598

A 1-1/2" hole is 1.767 square" and flows 65.9 cfm @ 5" which will test from 94 to 148 cfm @ 28"

A 1-3/4" hole is 2.405 square" and flows 89.7 cfm @ 5" which will test from 127 to 201 cfm @ 28"

A 2" hole is 3.141 square" and flows 117.2 cfm @ 5" which will test from 166 to 263 cfm @ 28"

A 2-1/2" hole is 4.908 square" and flows 183.1 cfm @ 5" which will test from 258 to 412 cfm @ 28"

A 3" hole is 7.07 square" and flows 263.8 cfm @ 5" which will test from 375 to 593 cfm @ 28"

A 3-1/2" hole is 9.621 square" and flows 359 cfm @ 5" which will test from 510 to 808 cfm @ 28"

A 4-1/4" hole is 14.186 square" and flows 529.3 cfm @ 5" which will test from 752 to 1190 cfm @ 28"

Swapmaster

The inclined differential manometer scale is just a percentage scale that gives
you the pressure differential pulled from each side of the orifice..

Cut a piece of 1/4" x 2" slat material 22" long. Drill a 1/8" hole 1/2" from each
end of the slat.. Sand it smooth and paint it white. Use a fine tip marker and
make a line 1" from one of the ends. From that line, make a line every inch for
20 inches to the other end of the slat.

Number the lines by 5's from 0 to 100, ei: 0, 5, 10, 15, 20, 25, 30, 35, 40, 45 etc.
The bottom of the scale is 0% the top is 100%. Then draw 4 lines between each
division to make the one percent incraments between the numbered divisions.

The scale will look something like this when you are done.

==100%==
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==95%===
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==90%===
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==85%===
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==80%===
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==75%===
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==70%===
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==65%===
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==60%===
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==55%===
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==50%===
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==45%===
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==40%===
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==35%===
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==30%===
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==25%===
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==20%===
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==15%===
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==10%===
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===5%===
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===0%===

The scale will rest at a 45* angle with the 100% side up to the left and the 0%
side down to the right. Attatch it to the back board with 2 small screws through
the holes you drilled in the ends of the scale. Run a length of 1/4" clear vinyl
tubing along the lower edge of the scale securing it with hot glue or whatever
and let it run past the top a few inches and curve it back down to the brass tube
running to the lower suction chamber (shop-vac side of the orifice).

Let the tube from the bottom of the scale run past the slat about 14". Hook the
tubing to the bottom half of a turkey baster (cut the baster in half). Hold the
baster up and start to fill it with colored water and position it so it is about 3/4
full and the water level at the guage is at the 0% mark. Attatch the baster to the
back board with hot glue or whatever so the water in the tubing is at the 0%
mark on the scale. Put a rubber stopper in the top of the baster with a small brass
tube through the center of it to attatch another lenght of 1/4" vinyl tubing that
will run back down to the brass tube running into the upper test chamber.

You will need to reverse the connections of the slanted manometer when you
test exhaust ports because you will be reversing the air flow. Don't forget to
swap them back for testing intake flows again. If the bottom of the manometer
is hooked to the wong tube the bench will suck all the water out of the baster.

This slanted manometer will now give the pressure differential between the
two chambers as a percentage.

Swapmaster

The cabinet will be 24" deep and 36" wide by 40" tall. The back will
extend up past the work suface for a total height of 7' from the floor.

The cabinet will be divided into two chambers. Half in the bottom
and half in the top. The divider will have an 8" hole cut in the center
the accomodate the orifice plates. The upper chamber will have an
airtight trap door to access the orifice plates. The top work surface
of the upper chamber will have a 5" hole in the center to accomodate
the test adapters.

The lower chamber will have two valves to regulate the test vacuum.
Each valve will have a flow through hole diameter of 2-1/2". The lower
chamber will have a 2" or 2-1/2" hole to the outside to connect a strong
shop vac. The bottom of the cabinet will have an adjustable screw out
leg on each corner to level the unit.

Swapmaster

Air flow calculation scale.

Take the reading from the slanted manometer and multiply the orifice flow
number by the percentage on the right side of this graph and that will be
your head flow at 10" water drop.

To convert to 28" water drop, multiply the head flow by 1.67332

CFM to CFM by change in water drop (vacuum).
( square root ( new vacuum / origional vacuum )) x CFM = new CFM

You only need multipliers for the 60% to 95% range of the slanted
manometer because this is where the scale is the most accurate.

Manometer % / Multiplier %
95% ======== 97.5%
94% ======== 97%
93% ======== 96.4%
92% ======== 95.9%
91% ======== 95.4%
90% ======== 94.9%
89% ======== 94.3%
88% ======== 93.8%
87% ======== 93.3%
86% ======== 92.7%
85% ======== 92.2%
84% ======== 91.7%
83% ======== 91.1%
82% ======== 90.6%
81% ======== 90%
80% ======== 89.4%
79% ======== 8.9%
78% ======== 88.3%
77% ======== 87.7%
76% ======== 87.2%
75% ======== 86.6%
74% ======== 86%
73% ======== 85.4%
72% ======== 84.9%
71% ======== 84.3%
70% ======== 83.7%
69% ======== 83.1%
68% ======== 82.5%
67% ======== 81.9%
65% ======== 80.6%
64% ======== 80%
63% ======== 79.4%
62% ======== 78.7%
61% ======== 78.1%
60% ======== 77.5%

Swapmaster

This one is simple. Take a 1/4" x 2" slat and cut it 22" long. Drill a 1/8"
hole 1/2" from each end. Sand it smooth and paint it white. Use a fine tip
marker and make a line in the center. Measure and mark off ten lines
1" apart from both directions from the center line. Number the center line
0 and mark the rest 1 to 10 going out to the ends. Attacth it virtically to
the back board with screws in each end. Run a lenght of 1/4" vinyl tubing
from a couple of inches above the right side, down to a couple of inches
past the bottom attatching it with hot glue or something. Loop the tubing
a couple of inches below the bottom and back up the left side and run it
past the top a couple of inches attatcing it to the back board again. Loop
the tubing back down and hook it to the ported plenum tube on the left
side of the work surface. Fill the tube with colored water so that the water
level reaches the 0 mark on the guage.

This guage will now measure 10" of water drop or pressure at the head.

Ions91Z28

So did you ever get it working? Pics?

Swapmaster

There it is boys. That's all the technical stuff.

Build a cabinet with a backboard extending well above the work
surface. The backboard will hold two scales, the water drop up to
10" and the inclined manometer which will give you the calculator
factors.

The actual cabinet will be divided by a shelf in the center to make
two equal sized chambers. The shelf will have an 8" hole in the
center which you will position the orifice plates over. The center
hole needs to be at least double the size of the largest orifice
you will use to avoid turbulance around the orifice. The lower
chamber will have a connection at one of the farthest corners for
the suction hookup to avoid turbulance at the orifice. The lower
chamber will have two bleed valves to allow test pressure
regulation. Use two 2-1/2" PVC ball valves glued into a lower
edge of the chamber.

The upper chamber will have an air tight door to allow you to
change orifices. The orifices will be mounted in the center of the
8" hole and be held down against a gasket to avoid air leaking
under the orifice plate. The orifice plates will be made from 1/4"
thick aluminum plate 12" X 12" square. The orifice hole will be
precision cut to exact dimension with sharp edges on either side.
Rounded or smoothed edges will not flow properly. Orifice edges
must be sharp.

The top work surface of the cabinet will be made from 1" particle
board to support the weight of the test item. The work surface
will have an 8" hole in the center which will require adapters to
reduce the hole size to accomodate the test item. The adapters
will need to be held down and gasketed to avoid air leaks. The
test item will need to be gasketed against the adapter to avoid
air leaks.

The upper chamber will have a 1/4" hole with a nipple to allow
connection of the water drop guage. This guage will be mounted
verticly and give you your test pressure. The upper chamber will
have a 1/4" hole with a nipple to connect to the lower side of the
inclined manometer. The lower chamber will have a 1/4" hole
with a nipple to connect to the top side of the inclined manometer.

To operate the unit:
Select and install an orifice plate you think matches the test item.
Open the two bleed valves on the lower chamber to allow air to
enter the lower chamber. Secure your test item to the work
surface with a proper adapter and gasketed to seal properly.
Turn on the shop vac and watch the test pressure guage. Slowly
close one of the bleed valves in the lower chamber and watch the
test pressure guage. You are after a 5" reading on this scale. If
closing one valve does not reach 5" slowly close the second valve.
If it still does not reach 5" then change to the next larger orifice.
If it goes over 5" with both bleed valves open then go to the next
smaller orifice.

When the test pressure guage reaches 5", take the reading from
the inclined manometer. If it is out of the 60% to 95% range,
install the next larger or smaller orifice. Over 95%, use a smaller
orifice, under 60%, use a larger orifice.

When you have the test pressure guage at 5" and an inclined
manometer reading between 60% and 95% take your multiplier
from the manometer and multiply it by the orifice flow factor then
multiply by 2.37 and you have the flow of your test item at 28"
of water drop.

Thats it in a nut shell.

Swapmaster

I have not had time to build it. I opened my own auto repair shop
and have been to busy to get going on it. I really need to though,
I need to see how bad I screwed up my Corvette heads.

Swapmaster

I just found this message board dedicated just to flow benches.

http://www.tractorsport.com//wwwboard.html

There is even a guy that built one with a 5 gallon bucket at
http://www.angelfire.com/ne2/antique...flowbench.html

Swapmaster

Holly cow batman! If you want to build a bench, here the place.
www.flowdyno.homeip.net