Hi Neil;
I have the 80 lpm version as seen here
When I first bought it many years ago, it was the only one
they had. All the other products are new since then. So when I
was looking to upgrade my controller to this new one, I ended
up buying the combo kit as shown here. (actually the
controller shown is even a newer design than the one I
recently bought).
So I have 2 of these pumps in series with one before the
rads and the other after the rads. The controller varies the
speed on the primary pump as needed and switches on the
secondary pump (with no speed control) as needed. The switch I
use for the secondary pump is meant for an electric fan.
If I was doing it again I would likely consider one of
the larger pumps. I don't know what you are using for a rad
but many builders now have a single large rad under the engine
and I'm not sure how or if that would have any effect on flow
ability.
I should mention that one recent change that I made was
with my rads. I'm one of those guys still using a set of old
ford pick-up evaporator cores on either side of my prop
spinner. I previously had them plumbed in parallel with the
thought that they may be less restrictive, but the problem
with that is you can never ensure equal flow through both and
the required plumbing was not really my favorite part of the
install. So I have now converted it to a series configuration
so all flow must go through both. It is more restrictive but
I'm ensured a far greater delta T and the plumbing is much,
much nicer. I installed a Mocal oil/water heat exchanger which
is what prompted this change, so I'm quite happy with it now.
Ground running so far it seems better than it was before.
But I'll wait until after full flight testing before
confirming that series is better than parallel.
Todd