I'm not certain of the pump model (Dave Atkins rebuilt the engine) but I
     > presume it is the stock 20B pump.  It seems unlikely to me that the screen
     > could make that much difference.  I estimated the total area of the screen
     > to be about 30 sq. cm.; and that the open area was about half of that.
     > However; if the domed screen is against the bottom of the pan, or the end of
     > the tube is near the screen (or both), the effective area would be much
     > less.
     >
     > Al

Al and group,
 The losses with the screen in place ARE REAL. There has been a great deal of
testing of various fluids, (including air) and bellmouth forms going all the way back
to the old NACA. The facts indicated are consistant, and working from memory,
losses when using a screen about 15-20%.This is especially true with air, less
with oil and other true liquids. This is the reason that all the modern auto intakes
use a large still air box with the filter far upstream. The same goes for oil no
screen is best. The use of the screen is often to prevent start up particulates,
like sealer and casting flash from breaking off and killing a new engine. If your
engine needs a screen after the first run in you have a bigger problem. Most
manufacturers use a screen, but usually the screen is on a opening about 6 to
10 times the size of the feed pipe. Motorcycles always use a screen, but they
have a different problem with the transmission running in the same oil. We do
have the PSRU to deal with so some gear flaking might happen. So if we stay
with a screen be sure to allow for a large inlet at least 5 or 6 times the pipe
diameter.
Bill Jepson

 
The Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2004 All world wide rights reserved.