Flowbench testing

[Anirudh]

Hey

I am kind of stuck and needed some advice.

We are building a flowbench for testing the cylinder head and the manifold. We are finding it hard to acquire vacuum motors/pumps. Standard flow testing is done at a pressure drop of 28" of water, And we are not sure if a certain vacuum pump will be able to attain 28" pressure drop. How can you validate your result for a particular pressure drop if the standard pr. drop cannot be obtained.

Also I intend to use a no. of vacuum pumps in parallel to get a higher cumulative pump capacity. How will this effect the pressure drop across the test piece.

Anirudh Raut

[Anirudh]

Hey

I am kind of stuck and needed some advice.

We are building a flowbench for testing the cylinder head and the manifold. We are finding it hard to acquire vacuum motors/pumps. Standard flow testing is done at a pressure drop of 28" of water, And we are not sure if a certain vacuum pump will be able to attain 28" pressure drop. How can you validate your result for a particular pressure drop if the standard pr. drop cannot be obtained.

Also I intend to use a no. of vacuum pumps in parallel to get a higher cumulative pump capacity. How will this effect the pressure drop across the test piece.

Anirudh Raut

[VFR750R]

Be careful using vacuum pumps. Most don't have much flow rate and you could end up requiring dozens to get the needed flow capacity.

Consider a supercharger, industrial air compressor ect that has high enough flow capacity to maintain your desired pressure drop across the valve at all valve lifts.
Added benefit of a system with this kind of pressure capacity is testing restrictors which require half an atmosphere to choke.

[Anirudh]

We have a vacuum pump that gives 40 l/s or 85 cfm.
And an air suction of 24kPa.

Will this be sufficient for testing the restrictor.

We have budgetary constraints and hence do not have the luxury of buying the industrial pumps of higher flow capacity.

we have a conversion chart that we can use to extrapolate the flow value at various pressures

Am i right to use such a chart for restrictor testing.

Thanks
Anirudh Raut

[ibanezplayer]

If you plan on choking your restrictor with that pump you might want to do your calculations again.

Is 40 l/s free flow or at a load of 24kpa?

just for approximations a 600 cc engine at 10k with 100% ve is moving 50 litres per second...

((1000/2)/60)*0.6 = 50 l/s

[Anirudh]

@ibanez

How do you suggest i proceed?
There is some confusion in my mind in this regard.
For restrictor choking how have you done the calculations, could you please elaborate.

As such we donot have a lot of feasible options for the vacuum pump.
In general the rating of the pump as mentioned on the companany's website says
Flow capacity/ Blower efficiency: 40 l/s
Air suction: 24010 Pa.

Thanks
Anirudh

[VFR750R]

Maybe call the manufacturer and get more performance information. You might be able to get a whole compressor map.

Luckily if you are doing ports/manifolds and such, you are going to be doing one cylinder at a time so the flow rate required is divided by 4. For the restrictor, that flow rate will probably not be enough to choke the restrictor, but it might be enough to see differences in restrictors.

If you already got the pump, just build the flowbench and see what happens. If you have to upgrade pumps down the road to do more so be it, but that pump should get you started.