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state of the art in british computing!

Old Splatterhand

great artwork! thanks a lot for the efforts, Lynn!

Lynn E. Hanover

The back box is the finish of the carpenty and the begining of the fun.



The output of the blower escapes up through the back box and out the holes at the top. A system of closing off some of the holes is required. My complex system is a board with soft foam glued to one side.



So, if you are working on a smaller (low flow) piece like a carburetter, you will close off some holes to make the upper monometer sensitive enough to work well. When you log each test, you will list which holes were closed for that test.



As above the test piece would be mounted on an adaptor block, like a piece of 3/4" plywood with foam on one side. The test hole is large to account for nearly anything being tested. So most items will require an adaptor. The test piece to adaptor junction must be air tight. A method to clamp the edges of the adaptor down is good also. Since everything affects everything, the downstream end of the test piece will affect its performance. Think long and hard about making the adaptor look like the next part of the total system. Or even carv up part of a like system, to include in the adaptor, so that the junction of the test piece and adaptor is not part of the test.



A small change in the flow available through the test piece hole, will have a dramatic affect on the number of CFM leaving the blower. This change then causes a change in the air pressure inside the back box. This change in pressure will be seen as a large movement in the water column in the lateral monometer. In this drawing the red stained (food coloring) water will move from left to right when pressure in the box goes up.

Notice that the plastic bottle has a hole in its bottom that exposes the water to room pressure.



The exact angle of the latteral monometer determins its sensitivity. You experiment with that angle to see what you like.



Start each test with the throttle closed. If not, and the test piece is not a high flowing item, the vertical monometer will empty into the box. If you want fancy, you can rig up a float in line with the run into the front box to eliminate that problem. One end of the vertical monometer is open to the room and the other to the inside of the front box.



Turn on the blower with the throttle closed. With the test piece in place and clamped down, Open the throttle

slowly. Keep going until you see how much vacuum you can pull on the test piece. Go all the way to wide open if possible. Watching the vertical monometer. For example, say you can get 8" rise in the water column.



Then back off the throttle so as to have room for the improvements you will make. So, back off to say, 5" of water. Record that number. Now look at the lateral monometer. Has it been moving as you jack around with the throttle?. If not, close off a hole or two until you can see some movement. Just 1/4" is plenty.



Reinspect the vertical reading as you go along with your improvements. Adjust to 5" for each pass.



For clarity I have not shown every detail I could have. A closed loop monometer along the front and one side will work as your levels, and the closed loop prevents evaporation.



An additional monometer with a long hose and a length of 1/8" brake line can be used to find low pressure areas inside openings. Keep in mind that the act of inserting the probe with have an effect by itself. Go slowly or you will empty this one also.



A great lateral monometer is a long glass tube. Plastic works also but stains after a while.



The vertical monometer will be emptied a few times while you get the hang of things. After that you can change to a plastic bottle supply like the latteral monometer. The first time you forget the rules you will be shocked by the cloud or red water landing on everything.



You can add bits of measuring tape along each monometer to keep track of data.





Sears, Home Depot and Lowes have all of the flow bench parts.



Lynn E. Hanover

bill shurvinton

Bother. tidied up the garage now, so no excuse not to fit one of these. Silly question, but is there a suitable way to calibrate things without heading over with a test piece to a friend who has a superflo.



Bill

Lynn E. Hanover

No.



The real good gizmo that gives very accurate readings costs a ton and is used on the intake side of the test piece. Fine for big 4 barrel carbs but not much else.



HVAC people have a similar gizmo to balance air conditioning systems, that you can fit over the outlet of the blower. Not quite as accurate but much cheaper.



I made up a bunch of square 3/4" plywood test pieces about 6" on a side, with differing hole sizes and a run of same size holes with inlet and outlet features different. Radiuses, tapers, inlet only, outlet only and so on.

I ran all of them on a Superflow. And recorded that data on each test piece.



I was driving from Columbus to Dayton on weekends to get time on Tom Pomeroy's superflow. (two time National champion in SuperVee, with no right arm and no feet) (Made Gengis Kahn look like an underacheaver).



That is where I got the smarts to build one. The diagram is in the superflow instruction book.



Write the flow rate and weather data on each test piece. Then when you want to know about how many CFM your pulling through a test piece, get out your calibrated test pieces and see how close you are to one of them. Correct for weather. Write it down.



After a while you will just work on improvements from item A to item B and won't care what the actual CFM is until no more improvement can be made. Then do the matchup to get a number. And write it down.



So you have a CFM number at the begining of a session, and again at the end. None of this is important unless you are in contact with another racer doing similar work, and want to compare performance over the phone.



You can make a flow bench that is much more sensitive than a Superflow. That short monometer with the steep angle is real hard to read a change. You make a long one just a few degrees above level, and it can detect a bee fart.



Most time will be spent between "made it worse, made it better". Use modeling clay to streamline things rather than grinding on an expensive piece. Then replicate the same surface contours as the clay with your die grinder. Polish like chrome when done.



I was wondering if anyone would use the plans.





Lynn E. Hanover

bill shurvinton

Oj I wo;; use them. Just don't know when. Been planning a home flow bench for 4 years now, just kids, job and megasquirt have gotten in the way (well when someone emails you wanting to put a T2 engine in an 1100lb kit car you just have to help them). In fact I have 3 sets of plans now. One from an old hot rod mag that uses 3 blowers and one from the internet that uses MAP sensors and a palm pilot to calculate flow. Between the 3 I should be able to work something out.



Now the old sofa has been evicted from the garage I have room for the bench. Just need time.

bill shurvinton

Just realised what the calibration gizmo is. Its a common or garden MAF, but with a superflow sticker on it and a cal certificate. Most of the common MAFs have cal curves available on line, although not to accuracy you need. In theory you could rip a GM MAF and ECU out the wreckers, pick up the scan tool off the web and hook it up a cheap and cheerful true flow meter.



The biggest problem with MAF is its not very sensitive at low flow rates as its a nearly exponential curve.



Hmm Got me thinking on something to try out. See now why I never get around to actually building a bench :-)

Mr. Midas

WOW!

Alot happened while I was gone. This is great reading material!



I have almost finished a new flow bench in my spare time. It is slightly different than your design. I'm using an old craftsman leaf blower, and instead of building a back box, I put a partition in the blower box(was that a good thing to do?). To adjust flow from the blower box I reused the intake cover of the blower and mounted it on the side. All I have left to do is to make up the manometers and backboard to mount them on. I'll try to get some pictures on later or tomorrow. Here is a simple drawing for now, and also, a link to a pdf manometer manual (tongue twister, eh?) from Meriam Istrument Co. It has all the basic instructions on proper usage and compesation.Link



Thanks again!





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heretic

Where?



This is just the info I need for my DIY EFI project.

bill shurvinton

What MAF is it?