Hi Karl,
> Other changes I had made since then was to increase the air exit
> area, close the gills, reduce the round opening on the stbd side by
> 70%, and reduce the large naca scoop by 80%.
The naca scoop is only for the 914. We build a closed cabinet around it,
where only the intake air filter resides. So the engine gets somewhat
"pressurized" air. The 914 doesn't use the naca scoop for anything else,
so you can safely scrap it on 912's.
> More recently I replaced
> the large main opening with a in-flight variable flap further down
> and back from the original.
Any pics? ;-)
I have the flap at the exit. Although I have not been flying, it seems
to work: can get the engine to overheat in a short time by closing it,
and cool down again from that position when opening it. ;-) In cruise
conditions my aim is to have roughly the same exit area as the inlet
area, so the velocity of the outgoing air is the same as the air around
it. Both the inlet and outlet have a diffuser. All to cut drag.
Closed off the gills. Added two naca inlets on top of the cowling with
the airflow aimed directly downwards onto the cylinders. This replaces
the two round inlets in the front which I intent to use for landing lights.
Now, as my engine runs very hot, I realise that my cooling mods are not
yet very convincing. ;-) But I started with a conventional setup, and
the engine overheated in 7 minutes from a cold start. In the TCU the
parameters indicated that my engine has been running for less than 1
hour before they shipped it. At the moment I have 3 hours on it, and it
now runs considerably cooler than before. Water and oil reach almost
redline at the same moment, so I assume there is not an airlock
somewhere. Now I can idle indefinitely without touching the red lines, I
will run the engine somewhat more to see if that gets the temperatures
down further.
> I know that some or maybe most Europas have no cooling issues at all
> with a bog standard installation, so I hope that you can get that
> resolved. Of course the 914 is putting out more heat, and I don't
As long as one does not exceed 80hp, the 914 shouldn't produce any more
heat than a 912. It is essentially a 912 but with a turbo bolted onto it.
> know if you have that baffle which directs air over the cylinder
> heads.
No, unfortunately I didn't know about its existance when I bought and
installed the engine. But instead I have my naca inlets with the airflow
aimed directly on top of the cylinders. On the ground it doesn't help
much though, as there is not much prop wash in that area (but that is
also the problem with the factory inlets and the Rotax baffle).
> Is the thermostat accurate ?
I have 4 CHT's and a coolant temperature gauge. They all agree with each
other.
Frans
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