Hi Rowland,
We have the Europa restrictor and with the new pump the fuel pressure comes
in at 5psi (the higher end of what is required).
We did some fuel pressure checks with an analogue guage and the pressure was
pretty much the same at idle and full power. I think the new Rotax pumps are
self regulating (pressure wise) soi the size of the rerstrictor would seem
to be irrelavent.
IMHO the more fuel that bleeds back to the tank the better (within reason)
as this keeps the temps in the engine bay as low as possible.
Carl - G-LABS
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Rowland Carson
Sent: 21 June 2013 18:20
Subject: Europa-List: fuel return line restrictor
--> <rowlandcarson@gmail.com>
While delving into the various Rotax manuals in pursuit of information about
the fuel manifold, I noted the dimensions of the restrictor in the fuel
return line - 0.35mm ID.
I have been considering the most elegant way to incorporate the restrictor
supplied by Europa (FS02) into my home-brewed alternative to the Rotax
manifold and so checked its dimensions. I find that the restrictor hole will
easily pass a number 71 drill bit, but barely accepts the shank of a number
70 drill bit. So I deduce that the orifice is about 0.7mm ID, ie twice the
diameter of the Rotax one.
Why should Europa have supplied a different size of restrictor from that
called out by Rotax?
Looks as though the Rotax orifice will (in any otherwise identical
circumstance) allow the fuel pressure to build up slightly higher, and
return less fuel to the tank, than the Europa one. It might just make the
difference between pass and fail in a fuel flow test.
Has anyone had any issues traceable to this difference between the
Europa-supplied restrictor and the Rotax one?
I might consider machining up my own manifold (obviously I'm heading into
deep water with LAA engineering here) and if so, which size of orifice
should I incorporate? Should it be removable, rather than integral, to allow
fine-tuning of fuel pressure?
in friendship
Rowland
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