pressure source

[mecrez]

just wondering what some more experienced people might have to say about this

i have an old 8-71 blower sitting around the shop, and have been considering that as a decent pressure(or lack of) source for a flowbench

I know i would have to have pressurized oil fed to it, but thats easy, i was thinking it could be driven with an electric motor

my only reservation is that like Bruce I would mostly be testing this on a garden tractor pulling engine, with that kind of an air supply I could have a lot of flow or a lot of pressure

My question is this, would it be possible to run it slow enough to get the lower flow numbers that I would like to be testing at, Or would I just always be doing ultra high pressure readings?


Matt

[bruce]

Ah . . . won't work sell it to me and I'll dispose of it for you

Whatca can do is add a bleed valve into your flowbench so you can bleed off the excess vacuum you don't need for testing at lower flows. I'm not sure on slowing it down, I wouldn't see why that would not work either? They do it on drag cars by increasing or decreasing pulley ratios, but then again thats still high pressure.

[84-1074663779]

I have never tried this myself, but see no reason why it would not work really well. If it still has the twisted rotors in it, pulsing should be quite low.

[mecrez]

using something like that, and yes it has the twisted rotors, would you need a plenum or could you just run 4" tubing directly off it?

I'm not really sure of the need for a plenum on a flowbenchexcept to help air stabilization, but that can be acheived by other means also, maybe someone could explain why there is a need for a plenum?

[84-1074663779]

Why not try it and see ? Fit a pipe stub and orifice plate and see if it can pull a steady pressure/vacuum without pulsing.

My own experience with roots blowers on engines, is that they do pulse and create quite a drone under high boost, but I have never tried one in a flowbench.