Hi Bob
If you take a look at 914 fuel pump testing site Gilles has put up:
http://contrails.free.fr/engine_914_fuel_syst_test_en.php
also Gilles take on pumps with link to Mfg.:
http://contrails.free.fr/engine_pierburg_en.php
, you can see the small surface area of Mini. The Mini is rated for I
think 160HP. Lets say that 100HP burns approx 10GPH, so that is 16GPH.
That is not an absolute using HP rating if you are returning a lot of
fuel! If you have parallel pumps, you can blow through 40GPH from what
some say! If you look at info, you can see that when I tested and restrict
intake it does work, but you can also probably fly toting a 5 gallon
garbage pail from the tail of your plane (more easily attached I might add
if you didn't have an "UnConventional gear!). It strains the pump big
time. In addition it can create cavitation that boiling bubbles of fuel
will do no good to life of pump or the strain to life of motor. Pump Mfg.
states head max., adding intake restriction pretty much equates to higher
head. You can also run without a filter at all, as long as you put in
clean fuel, but not recommended. To stack things in your favor, at minimum
match flow recomended by Mfg. to what your worst case needs are. 375 adds
a tremendous amount more filter surface area compared to Mini and does not
add that 5 gallon bucket (I forget exact but think 375 rated for 250 or
275 HP). Recommended Europa fuel schematic, series with bypass, 2 filters
(or gasculators) plumbed as per their schematic better on 914 than having
1 filter (or gasculator) at each tank output. Unless you had a
differential pressure gauge for 914 (which every 914 driver should have,
and know how to use it) and saw bouncing needle (crack pressure bear being
met) and switched selector at that moment on take off, you are in position
to run out of fuel. Europa schematic will keep you going. Once you fully
understand approx. 2 to 5 PSI over airbox pressure, you see you don't want
any restriction in plumbing from fuel pressure regulator to tank, and
downside of paralleled fuel pumps compared to series (blow over 5 PSI, not
as bad as under 2PSI but you are stacking things not in your favor, best
follow Mfg).
I would not recommend a Mini even for 912/S even though you can probably
get away with. Restriction is so close, some builders putting supplied
filters in series with Mini makes for marginal flow and easy chance of
failure.
Ron Parigoris
On Sat, Nov 3, 2007, "Robt.C.Harrison" <ptag.dev@tiscali.co.uk> said:
>
> Hi! Graham
> Just a little alarmed with your statement questioning the suitability of
> the Mini-Andair gascolator. I used a single unit throughout my Jabiru
> 3300 heavy fuel use experiences with no problems other than those, not
> Andair related, manifested by the damn tank comnector finger filters
> and drillings.
> I now have two Mini Andairs on each fuel line so theory has it that one
> should remain gunk free for the emergency situation albeit with a 914?
> Clean system flows were well in spec. before flight testing.
> Regards
> Bob Harrison G-PTAG
>
> -----Original Message-----
> From: owner-europa-list-server@matronics.com
> [mailto:owner-europa-list-server@matronics.com] On Behalf Of Graham
> Singleton
> Sent: 03 November 2007 10:29
> To: europa-list@matronics.com
> Subject: Re: Europa-List: fuel system
>
> <grahamsingleton@btinternet.com>
>
>
>
> rparigor@suffolk.lib.ny.us wrote:
>>
> Ron
> a lot of good sense in what you say.
> The Andair gascolators have 120 mu mesh, because Rotax specify minimum
> of 100mu filters. They couldn't buy 100mu at the time I discussed it
> with them. Those nice Mr Funnel filters are around 70mu (if I remember
> right) and they WILL allow dust through that will block an Andair Mini.
> I know of one blockage with a 914, caused by rust from a Jerry can. The
> Mini is probably OK for 912S but not 914 with the high recirculating
> flow rate.
> Graham
>
>> Did you clean the filters in your fuel pump after a few hours of
> running?
>> If you didn't probably worth while. See:
>> http://contrails.free.fr/engine_914_fuel_syst_test_en.php
>> for some good 914 info
>> I would not consider using Mini, in a perfect clean world will
> probably
>> work, but very little surface area, stick at least with 375s or
> supplied
>> filters instead of Mini.
>> For info on this post see folders:
>> 914 modular fuel system
>> Spring loaded down detent
>>
>> Ron Parigoris
>>
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>
> --
> Graham Singleton
>
> Tel: +441629820187
> Mob: +447739582005
>
>
>
>
>
>
> --
> 02/11/2007 21:46
>
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