[polg0003]

I am attempting to do knockdown texture on my ceiling. The compressor I have is a Dewalt D55168. It rated at 5 CFM @ 90 psi.

The hopper gun i have is a Wal-Board Texture-Pro 200. It calls for 2.4 CFM @ 90 psi.

Can i make this work?

 

[mako1]

The compressor is probably overated at 5 cfm and the texture gun will shoot a lot better at more than 2.4 cfm.Do not use 90 psi.
Thin the mud to get a mayonnaise like mix.Maybe a bit thinner.Add a bit of of Ivory dishwashing soap to the mud.Set your compressor to 45-50 psi and test it on a scrap or piece of cardboard .You'll have to mess with the mixing valves on the hopper to get it right.
The set up with this compressor and hopper is borderline but workable.

 

[ToolSeeker]

For knockdown I might start a little lower around 35-40

 

[polg0003]

Does the CFM effect the proper PSI?

 

[mako1]

Yes.But for what you are doing as far as spraying texture it's a good thing.Set the compressor at around 40-45 psi for the hopper gun and you will have more cfm than you will at 90psi.Plenty of pressure for spraying texture.
Don't do like some do and keep turning up the pressure if the gun does not work correctly.Adjust the gun or thin the mud.It takes a little practice to get things tuned properly and the correct consistency of the mud but 40-45 psi is plenty .Adjust everything else accordingly.