Small Garage Flowbench Build

[jfholm]

Stef,
You do good work. Your programs for designing the intake systems is awesome. This one for the flow bench looks great also.

John

[stef-1]

Doug - I'm pretty certain we could test your plates this saturday

John - Thanks for your comments. Would you mind emailing me about your experience to date with the intake stuff? I am planning a few changes to it and would appreciate the feedback.

[UKDoug]

Saturday morning would be good for me too

I'll give you a bell tomorrow

[stef-1]

I tried to have a go at reducing the manometer bounce this evening. I pulled out all the pickups and soldered the ends. I then drilled a 1.5mm dia hole in them. I refitted them and fired it up with the magnehelic gauge hooked up. The amplitude of the bounce was reduced to about the width of the needle. I took a video of it in action. The quality is not that great but you can see the needle moving. I'll need to test it next with the vertical manometer hooked up once I've finished the new wells.



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I started to make the wells too. The lab jars are 80mm dia ones so that the area is enough to not really have any effect. I fitted the through-hull fittings to them. I'm getting some pipe clamps shortly which I'll use to fix them to the boards.

[stef-1]

Today I received my clippard valves courtesy of Bruce (cheers chap )



I needed to mount them to the backboard so I cut a hole out ready. Then I marked out a mounting panel on some 1/8" aluminium sheet, cut it, drilled it and mounted the assembly to the board.







Routed all the airline tubing.



Added the clamp and well to the vertical manometer. The clamp was fixed with its legs slightly wider apart than normal and I added a screw with wing nut. This allows me to slide the well up and down to zero the manometer and then nip up the wing nut to clamp the well.



After doing this I filled the well with fluid and fired the bench up. Two things I noticed;

1. There is still some bounce. On the vertical manometer its amplitude is about 1/8" - is this okay? Not sure what I can do the get it totally steady now.
2. The magnehelic gauge reads 1" H2O lower than the manometer. It does this at all ranges. I'll have to assume that because the manometer is a simple device (and I think a primary standard?) the magnehelic is slightly inaccurate.



So, now I need to fit the incline manometer well and do some trouble shooting. At the weekend UKDoug will pop over with his calibration plates and we can see how accurate this thing is.

[stef-1]

Well the construction is finished now and it's up and running.



But... it still has the manometer bounce problem. After searches on here I've tried the following;

Adding a large volume damper to the airlines - no effect.
Adding a damper filled with cotton wool - had a smoothing effect but altered how the incline manometer worked and made response slow.
Added "jets" made from mig welder tips (0.6mm dia) - small effect, not enough.
Cut down the pickups so that the tappings were flush with the plenum walls - small effect, not enough.

After reading some more on orifices with small beta ratios it seems that the tappings may be in an area of recirculation and there is not much I can do to reduce the bounce.
My alternative at the moment is to remove the back board, counter top and back panel from the bench (a tough job!) and to construct pickups similar to the Superflow ones which sense much closer to the orifice plates.

Maybe after some thought on this issue I may be able to come up with something else. I know electronics can help by averaging out pressure variations but it would be nice if it was accurate without them.

[coulterracn]

I found an article online about a DIY manometer. The builder used a fuel filter to dampen the meter fluid allowing a steady level at test pressure. I have not tried this procedure but I am considering doing so on my bench.

I do not remember the website or I would gladly post it. Has anyone else here heard of using a fuel filter as a dampener inline with the manometers?

Ray

[coulterracn]

In the DIY flowbench article the builder used a needle valve from a garden irrigation system to control pulse in the manometer. The valve is shown in the pictures and mounted to the top of the backboard that the incline meter is mounted on.

www.dtec.net.au/

[coulterracn]

[color=#000000]I found this link on a Corvette forum

www.thecubestudio.com/CrossfireHomeBuiltManometer.htm


OPTIONAL STEP


Your water manometer is exactly as accurate as anything you can buy. It is also very . . . responsive, shall we say. If you hook your manometer up to the port when it is pulling a lot of vacuum, you have .001 seconds to disconnect it before the water goes bye-bye. Don

[msj442]

what about the size of the tubing? what is the i.d.? it seems i remember reading about the size of the tubing can affect how the mano performs. i thought .125 was max size that should be used.

jmo, max

[49-1183904562]

Stef,

I would look at some voltage stabilization, Listen to your motor/s run Does it have a wavering sound?
Unlike the PTS bench using motor speed control you have to run your motors flat out and control air via air valve, this can cause the motor to load and unload kind of like cavitations. If you have access to a simple motor controller you could test this by bypassing the air valve and control one or two motors and test Bounce or no bounce.

Just some thoughts

Rick

[jfholm]

Rick has a good idea there. Another one that was mentioned was tubing id. Here is some food for thought. Back in the "old" days when I was really racing all the time we lost an engine because the oil pressure went away and we did not see it due to lag time in the gauge. Heavy oil small diameter tubing. Gauge would sweep smoothly but rather slowly. We installed a new line from the engine to the gauge that had about 4 times the area. The gauge responded like a tachometer after that. The draw back was the needle was not smooth anymore because it could pick up every little pulse from the geared oil pump.

Just something to think about as air is much thinner than oil and is also compressable.

John

[stef-1]

Thanks for the suggestions guys. The tubing is 6mm O.D and 4mm I.D. I don't think it's causing the problem. The voltage stability is something I thought about and the motors do indeed change pitch slightly when running. But, if the Superflow benches can run flat out and not get bounce then I should be able to get mine to also?

UKDoug came over today with his PTS orifice plates for testing. We ran it with the 1.92" plate on top and the 2.54" plate in the bench. The 1.92" plate is calibrated for 200cfm at 16"H2O. The manometers were bouncing about and with the best averaged reading on the incline I calculated that the plate flowed 192cfm. Close but no cigar. Maybe I have a leak also :O





Before UKDoug came over I had been thinking how I could try moving the pickups. I was dreading having to remove the back panel of the bench after it had been painted and sealed. Then I remembered that the portholes were bought in packs of two. I dug around for the spare and found it. Now I had a means of accessing the lower plenum! Don't know why I had never thought of installing it in the first place - numpty!
After UKDoug left I measured the porthole up and marked the front panel of the bench before cutting the hole and installing the porthole. I fitted a handle to it to match the rest as well.









Then I made some more pickups which were longer so that I could attatch some tubing to them.





Playing around with the positions of the tubes did improve things but I ran out of time to test. I'm on vacation next week so it won't be until next weekend that I can test some more. I may look into the motor control also - the throttle control works great for rapid changes but it can be awkward for fine adjustments.
I'm glad that the machine is basically working as intended it's just trouble shooting and calibration now to get it perfect

[johno]

My bench uses a fluid vertical 'U-shaped' manometer with 4mm id tubing and i found if i inserted a 0.50mm webber idle jet into the tubing it ironed out any pulsing nicely. Just play with jet sizes until you find 'the one' that fixes your benches problems as its design is unique in itself. I also noticed in your build that you may be using a mixture of vac motors. If the motors arent all identical units you may find they are "cycling" as the less efficient units fight the larger ones for air!!

[jfholm]