Okay, round two of pressure readings on the small orifice (11/32") Leitinger nozzle
First off, I had a strange mis-match in my water levels, about 1/16" that would not go away no matter what I did. I am not sure how to explain that, so all measurements are +/- 1/16" I guess?
@bsoutherland: I did a test on the filter resistance, and found it to be quite small. Here is the initial reading, with the fan pulling just shy of 1.5" of water through the filter. I figured that would be a good value, as it is what I will be shooting for with the engine draw.
Next, I pulled off the wool sock filter, and removed the wool batting that fills my ammo can.
Overall, my filter is reducing the suction by about 1/8" of water column. I cleaned it out - it had a little dust in the sock - and ran it again at a lower draw and got the same results.
Next i fired up the engine and took some readings of it during idle and under load. At first it was drawing about 3" at idle, but after maybe 5 minutes of warm up, it had settled down to about 2 1/4".
When I connected the space heater, it pulled a little harder, rising up to about 2 3/4"
I am curious about the drop in pressure as the engine warms up, any thoughts on that?
Seems like the takeaway here is that I am indeed choking the engine- it draws 57mm at idle, and about 70mm while at its maximum load. I think I will try boring the nozzle out to 1/2" next, and repeat the pressure testing at idle and under load. I will also check and see if that will give me more power to work with.
I figure while I have it torn down, I will also add an EGR system, and maybe slap some cooling fins on the sides of the reactor.