> > This also accounts for another anomaly I've noticed over the years.
> It
> > seemed like the water cooling was slightly better on the first flight
> > after
> > topping off the system.  I was never sure because the next flight was
> > usually on a different day, different temperature, humidity, etc.  Now
> > that
> > I've been paying close attention I have verified that only a few
> ounces
> > worth of air in the system makes a noticible degredation in cooling
> > performance  (about 5 degrees worth).   Not sure why this is happening
> > either but I'm happy with the results.  With more experimentation the
> > answer
> > will probably come out.
> >
> > Tracy Crook
> > tcrook@rotaryaviation.com
> > www.rotaryaviation.com
> Tracy,
> FWIW, the 93+FD owners have known this for years. Just a little air
> screws up the cooling system performance big time. They even have
> elaborate procedures to "burp" the systems to get rid of all air.
> Sometimes it takes all afternoon to get all the air out of a system. And
> these systems use an entrained air bubble remover 'swirl pot' as well to
> vent out the bubbles before the system is connected to the overflow
> tank. Of course the positions of all the components may have
> necessitated some of the components. On the attached pic I put an arrow
> pointing at the "swirl pot" (with the .9 bar cap). You can see the
> tubing from the other pump cap to it. From the bottom of the swirl pot
> additional tubes route to the expansion tank.
> [Marc Wiese]
>
Thanks for the conformation Marc.  Data is a lot more reliable when it is
repeatable.
I'll pass along another anomoly  I've noticed.  Maybe someone else has seen
this one as well and knows an answer.  I have replaced my pressure cap
several times with a Stant 16 PSI cap.  It seems to hold 16 psi when new but
in very little time (10 - 20 hours of use?) the holding pressure is down to
around 10 psi where it stays.  Anyone else see this?  I'm going to order a
20 psi cap from CR Racing & see if it does any better.

Tracy