Hi everyone,
As some of you know I have drastically changed the cooling system of my
914 powererd Europa and achieved perfect cooling without having to
resort to more and larger openings in the cowling. Even better, I think
I have only about 50% of the original air flow left at maximum cowl flap
angle and about 10% of this during the cruise. Less cooling air is less
cooling drag, which is a significant percentage of the total drag of an
Europa. It is one of the keys why I can easily cruise at 140 knots with
my hi-top tri-gear. (Sorry, still didn't got time to write the promised
article about this).
So, with so much cooling overcapacity I thought to make the transition
---From 50/50 to Evans coolant. Reason for that was to be able to allow the
engine to run slightly hotter (good for the efficiency) and to have zero
pressure in the cooling system (which is good in case of a leak).
One key element in my cooling system is the Laminova oil to water heat
exchanger. This marvel has very fine oil and coolant passages to ensure
good heat transfer.
After swapping the 50/50 coolant for Evans I started the engine... and
it was interesting to see the CHT's to increase very fast to 100C while
the coolant sensor was still at ambient temperature. Coolant flow in the
system appeared to be about zero.
I thought of an air lock initially, but after much rocking and
disconnecting hoses at key locations I was quite sure that I didn't have
an air lock (I never had to resort to any of such trickery during the
cooling experiments with 50/50).
So, that Evans stuff simply appears to be too thick for the tiny canals
of the Laminova heat exchanger. When the oil finally warms up by itself
(without the use of warm coolant as usually was the case, so this takes
a long time) the flow improves somewhat, but the best I got was a 30C
difference between the CHT and coolant (on the ground at low power). It
is not flyable. With 50/50 the temperature difference between the CHT
and coolant is almost nothing, indicative for sufficient coolant flow.
So, my question to anyone who has or is using Evans coolant: Did you see
a large difference between the CHT's and coolant temperature? Has anyone
ever tried to use Evans in combination with a Laminova/Mocal heat exchanger?
On the Evans website a new type of coolant is announced, with higher
viscosity especially for motorcycles that have smaller radiators with
smaller canals. (Apparently there are more folks having problems with
the regular thick Evans stuff). Has anyone tried that in an Europa? And
more importantly, am I allowed to use it in my Rotax?
I'm back to 50/50 for the moment (too bad for my dewatering efforts
prior to pouring in that Evans stuff).
Anyone interested in my can of Evans NPG+? Used only once! Never flown
with it.
Frans
|