Mailing List flyrotary@lancaironline.net Message #24297
From: Leon <peon@pacific.net.au>
Subject: Re: [FlyRotary] Re: "Surge" tanks and air bleeding was Re: [FlyRotary] EFI Fuel Testing
Date: Thu, 23 Jun 2005 01:03:42 +1000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Hi Al,
 
The bigger the sump is the better.  AS long as it is deep and narrow and can't slosh and uncover the EFI pump pickups.

As for Air Locks,  I've experienced them a couple of times in race cars.  One in particular drove me nutz for several days,  and cost me much time and money for dyno time.  If you go back to the 15/06,  I posted about this episode.  I believe that this was Paul Conner's problem as well.
 
I've forwarded the relevant email to you separately.  The issue is that theoretically,  any air in an EFI high pressure line SHOULD purge,  but in practice,  it often doesn't.  It all depends on the diameter of the line.  The problem usually occurs at the junction of a flexible hose with the steel fuel lines.
 
I can only tell you that it IS a reality,  and to watch out for it if you happen to experience funny partial power problems.  It is just one of those little things that experience has taught me to look out for,  and I merely pass it on as something to consider.

Cheers,

Leon
(Still trying to talk my dragracing mates into comparing BSFC figures of their V8s!). (}:>^)
----- Original Message -----
From: Al Gietzen
Sent: Thursday, June 23, 2005 12:46 AM
Subject: [FlyRotary] Re: "Surge" tanks and air bleeding was Re: [FlyRotary] EFI Fuel Testing

 

Additionally,  anywhere you get an air lock (as opposed to a vapour lock),

you will have trouble passing fuel,  so any unavoidable  high points/loops

etc in the system should have some sort of bleed nipple.

 

Leon;

 

My system is essentially as you describe except my sump is larger (2 ½ gal).  I assume the above statement refers to ‘before the pump’ because I don’t see any issue with a high point in the line downstream from the EFI pump.  My experience is that any air in the line is easily pushed through and past the regulator back to the sump.  And why not – the only resistance to it moving through is the very small pressure head between the high point and the regulator.

 

Al

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