Flow bench update

[Dave Moran]

Well, the flow bench project is comming along, finished the internal wiring yesterday and did a smoke test, both ways. First we powered each pair of vaccuum motors to verify operation, all OK. Then we closed it up and put it under vaccuum with 2 pair of motors, my shop can't power more than 2 pair at a time, and ran a cigarette past every seam, the smoke went straight up NO LEAKS!!!

We used a piece of scrap 3/8 ply to seal the input port and I almost broke it trying to lift it with the vaccuum on.

[Randy Meijer]

I have no idea what a "flow bench" is?? And why all of the motors??

Any help for this newbie??

[Dave Moran]

Hi Randy, I am the woodworker not the gearhead in this project so my explaination may not be exactly accurate, but it is as I understand it. For race engines they modify and polish the intake and exhaust manifolds, this is so they can measure the actual flow and see the improvement before putting the engine back together. The motors are vaccuum motors to provide the vacuum for an intake manafold or the pressure for an exhaust manafold. The big silver discs are the valves, one for the pressure side and one for the vacuum side, you vent the one you are not using to the atmosphere.

[Randy Meijer]

Got it. thanks!!

[David LaRue]

Interesting. Along time a go I used to pit crew on blown fuel hydo (boat0 and worked at www.kinsler.com we flow tested manifolds, injector flow rates etc., but it was all fluid tests. Played with aero stuff in college, but not with vacuum. It would intesting to see how the system looks hooked up to what its testing.


David

[Dave Moran]

David, This pic may give you a better idea. You can see the valves directly above them is a disk with calibrated orifices, mounted on top of the upper angled board, manometer probes are installed in each chamber to measure the differential pressure across the orifice with an 26 degree angled manometer, 0 to 10 inches of water differential, the upper chamber is operated at 28 inches of water relative to atmosphere measured on a u-tube manometer. The top board shows the working port where the head is mounted with an adapter. All the manometer readings are entered into a computer that gives them the flow numbers they need.

[David LaRue]

We used to use a manometer to do the final tune on our Holly double pumpers. We would measure th #inces of mercury at each volocity stack.

In the newer fuel injected street cars some use a variable thirister / air vane or a hot wire resistance to measure air flow to determine the dithering rate of the electronic fuel injectors. (precalibrated in the (ECM) electronic control module and with the ability to modify by flashing the EEprom)

I'm assuming (big leap here) that the manifold, or device you are measuring sits on top of the box, and you apply a vacuum through it and using the mamometer you measure the resistance to flow in pressure drop?

David

[Dave Moran]

David,

Yes, the manifold under test sits on top, the actual flow is calculated by the drop across the calibrated orifice. I have no idea what the math is, I design fiber optic transport systems not flow systems for a living.

Dave