X-Virus-Scanned: clean according to Sophos on Logan.com X-PolluStop: No license found, only first 5 messages were scanned Return-Path: Received: from mailout2.pacific.net.au ([61.8.0.85] verified) by logan.com (CommuniGate Pro SMTP 4.3.4) with ESMTP id 993598 for flyrotary@lancaironline.net; Mon, 13 Jun 2005 01:09:11 -0400 Received-SPF: none receiver=logan.com; client-ip=61.8.0.85; envelope-from=peon@pacific.net.au Received: from mailproxy2.pacific.net.au (mailproxy2.pacific.net.au [61.8.0.87]) by mailout2.pacific.net.au (8.13.4/8.13.4/Debian-1) with ESMTP id j5D58PGm023356 for ; Mon, 13 Jun 2005 15:08:25 +1000 Received: from ar1 (ppp2711.dyn.pacific.net.au [61.8.39.17]) by mailproxy2.pacific.net.au (8.13.4/8.13.4/Debian-1) with SMTP id j5D58Kmt004509 for ; Mon, 13 Jun 2005 15:08:21 +1000 Message-ID: <005001c56fd4$7075ded0$1127083d@ar1> From: "Leon" To: "Rotary motors in aircraft" References: Subject: In Tank EFI Pumps was Re: [FlyRotary] Re: EFI Fuel Systems was Re: [FlyRotary] Re: Is common sense dead (rant mode on) Date: Mon, 13 Jun 2005 14:57:44 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_004D_01C57028.417B4E90" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 This is a multi-part message in MIME format. ------=_NextPart_000_004D_01C57028.417B4E90 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Georges, Don't tell me that, I might get a swelled head (}:>). Yair, in-tank pumps are fine. just put 'em in a nice deep "surge" tank = with a false floor (baffle) and a drain to separate out any water. As = long as the filtration mechanism is readily and easily serviceable. (I = just HATE having to replace GMH Holden in-tank pumps though - they = require draining the tank, and irespective, you can still get your arm = pits soaked in fuel if you are not careful. Nissan got it right with = vertical access through the boot (trunk) floor. Really nice. The crucial issue is that if we follow normal proven auto practice, (of = which I know you are a master), we shouldn't ever have any mechanical = EFI problems (computers aside - a different can of worms). It's only = when neophytes try to "improve" on what is known to be settled = technology that strange problems can arise. =20 I have always been impressed with the utter reliability of Bosch & = Nippon Denso EFI componentry. Properly serviced, and supplied with = clean, filtered, dry fuel, everything seems to last for ten or more = years. The Mazda rotary EFI stuff rarely gives problerms unless it cops = a load of water or really dirty fuel. Even then, normally all that is = required is just a filter change. Cheers mate, Leon =20 ----- Original Message -----=20 From: Echo Lake Fishing Resort (Georges Boucher)=20 To: Rotary motors in aircraft=20 Sent: Monday, June 13, 2005 10:50 AM Subject: [FlyRotary] Re: EFI Fuel Systems was Re: [FlyRotary] Re: Is = common sense dead (rant mode on) Hi! Leon=20 You make sense as usual, can you see any reason not to use in- = tank EFI pumps in a header tank instead of external units (I happen to = have 4 in stock). Georges B. -------Original Message------- From: Rotary motors in aircraft Date: 06/12/05 14:35:43 To: Rotary motors in aircraft Subject: [FlyRotary] EFI Fuel Systems was Re: [FlyRotary] Re: Is = common sense dead (rant mode on) Hi Guys, Gotta chime in here. This risk analysis stuff is all very = interesting, but fails to get to the important points, based on common = sense and practical experience. How the hell can you ever get a vapour lock in an EFI system?? = In an EFI system, the fuel is supposed to ALWAYS be at a POSITIVE = pressure of at least 30 PSI. At WOT, that pressure climbs to 45 PSI. Vapour locks normally occur in a mechanical system where a lift = pump is "sucking" fuel from the tank and supplying it to a carburettor. = Classic case occurs on a V8 where the fuel will boil in the supply line = because of the close proximity of the fuel line to an exhaust header. = Bad initial design, which can be corrected by either re-routing the = fuel line, and / or shielding it and insulating it. Further, the vapour lock can only occur if the system is at = high temp, and the fuel line is subjected to a partial vacuum of a lift = pump. So the only place it is possible to get a vapour lock in an EFI = system is in the low pressure supply side when using a lift pump. If = you are SILLY enough to have your EFI pump higher than the fuel supply, = you can also get a vapour lock. EFI pumps are NOT designed to "Suck" = anyway - they are blowers or pushers. Proper fuel system design requires that at all times, the lift = pump AND the EFI pump(s) SHOULD ALWAYS have a head of fuel on them so = that they are not required to "Suck" fuel, and therefore can't subject = the fuel supply line to a partial vacuum. The lift pump SHOULD supply what is commonly known as a "Surge" = tank, or a header tank, or a "make-up" tank. This tank, whatever you = want to call it, is used to supply EFI pump(s) with a positive head of = fuel. That is the way the system MUST be designed. If you do it any = other way, sooner or later, it will bite you on the backside. = Guaranteed! There is another possibility in a badly designed fuel system. = AIR lock. Having experienced it myself, an air lock in the supply line = is quite capable of reducing flow in the high pressure side of fuel = supply. I won't bore you with specific details, but I have had it = happen on more than one occasion. It will normally occur where the fuel line is higher than either = the fuel rail or the injector supply. In such cases, it is imperative = that a bleed nipple is installed to bleed out any air. This will be = most evidenty where there is no fuel return. My personal opinion is = that anybody that runs an EFI system without a proper fuel return is = just asking for it. A fuel return will assist, but will not = necessarily eliminate an air lock in the fuel supply. There is a minimum system configuration complexity in any EFI = system, below which, if you try to simplify it any further, can cause = problems under certain conditions. I KNOW that many current model cas = have returnless fuel sustems, but the design is quite complex, and = unless you understand the differences, you will not be able to = implement such a system. ----- Original Message -----=20 From: al p wick=20 To: Rotary motors in aircraft=20 Sent: Sunday, June 12, 2005 4:39 PM Subject: [FlyRotary] Re: Is common sense dead (rant mode on) On Sat, 11 Jun 2005 21:48:53 -0500 "rijakits" = writes: Everyone here is interested in solutions, SPECIFIC solutions. Specifically, Follow this general principal: When you have a theory, find way to prove it's true. Use facts.=20 Example: I think my fuel system is not going to vapor lock. Measure it. Place pressure gage on the fuel inlet to the pump. = There is direct correlation of INLET pressure to vapor lock risk. = Measure the pressure and compare to other aircraft. If you have unusual = aircraft, also measure with nose down, nose up. Get a coffee can of fuel. Have one person in your group measure = the pressure change while adjusting the following: Pump temp. head pressure. reduced atmospheric pressure on tank inlet filter Fuel type This info provides perspective as to how significant each is. It = can be tested easily with coffee can. The result: the entire group has lower risk because they can = measure how close they are to vapor lock when ground testing.=20 -al =20 =20 =20 ------=_NextPart_000_004D_01C57028.417B4E90 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Georges,
 
Don't tell me that,  I might get a swelled head = (}:>).
 
Yair,  in-tank pumps are fine. just = put 'em in a=20 nice deep "surge" tank with a false floor (baffle) and a = drain to=20 separate out any water.   As long as the filtration mechanism = is=20 readily and easily serviceable.  (I just HATE having to replace GMH = Holden=20 in-tank pumps though - they require draining the tank,  and=20 irespective,  you can still get your arm pits soaked in fuel = if you=20 are not careful.  Nissan got it right with vertical access through = the boot=20 (trunk) floor.  Really nice.
 
The crucial issue is that if we follow normal proven = auto=20 practice, (of which I know you are a master), we shouldn't = ever have=20 any mechanical EFI problems (computers aside - a different can of=20 worms). It's only when neophytes try to "improve" on what is known = to be=20 settled technology that strange problems can arise. 
 
I have always been impressed with the = utter reliability=20 of Bosch & Nippon Denso EFI componentry.  Properly = serviced,  and=20 supplied with clean, filtered, dry fuel,  everything seems to last = for ten=20 or more years.  The Mazda rotary EFI stuff rarely gives problerms = unless it=20 cops a load of water or really dirty fuel.  Even then,  = normally all=20 that is required is just a filter change.
 
Cheers mate,
 
Leon 
 
----- Original Message -----
From:=20 Echo=20 Lake Fishing Resort (Georges Boucher)
Sent: Monday, June 13, 2005 = 10:50=20 AM
Subject: [FlyRotary] Re: EFI = Fuel Systems=20 was Re: [FlyRotary] Re: Is common sense dead (rant mode on)

 Hi! Leon
You make sense as usual, can you see any reason not to use = in- tank=20 EFI pumps in a header tank instead of external units (I happen = to have 4=20 in stock).
Georges B.
 
-------Original=20 Message-------
 
From: Rotary motors in=20 aircraft
Date: = 06/12/05=20 14:35:43
To: Rotary motors in=20 aircraft
Subject: = [FlyRotary]=20 EFI Fuel Systems was Re: [FlyRotary] Re: Is common sense dead = (rant mode=20 on)
 
Hi Guys,
 
Gotta chime in here. This = risk=20 analysis stuff is all very interesting,  but fails to get = to the=20 important points,  based on common sense and practical=20 experience.
 
How the hell can you ever get a = vapour lock=20 in  an EFI system??    In an=20 EFI system,  the fuel is supposed to ALWAYS be at = a=20 POSITIVE pressure of at least 30 PSI.  At WOT,  that = pressure=20 climbs to 45 PSI.
 
Vapour locks normally occur in = a mechanical=20 system where a lift pump is "sucking" fuel from the tank and = supplying=20 it to a carburettor.  Classic case occurs on a V8 where the = fuel=20 will boil in the supply line because of the close proximity of = the fuel=20 line to an exhaust header.  Bad initial design,  which = can be=20 corrected by either re-routing the fuel line,  and / or = shielding=20 it and insulating it.
 
Further,  the vapour lock = can only=20 occur if the system is at high temp,  and the fuel line is=20 subjected to a partial vacuum of a lift pump.  So the only place it is possible to get a = vapour lock=20 in an EFI system is in the low pressure supply side when using a = lift=20 pump.  If you are SILLY enough to have your EFI pump higher = than=20 the fuel supply,  you can also get a vapour lock.  EFI = pumps=20 are NOT designed to "Suck" anyway - they are blowers or=20 pushers.
 
Proper fuel system design = requires that at=20 all times,  the lift pump  AND the EFI = pump(s) SHOULD=20 ALWAYS have a head of fuel on them so that they are not = required to=20 "Suck" fuel,  and therefore can't subject the fuel supply = line to a=20 partial vacuum.
 
The lift pump SHOULD supply = what is=20 commonly known as a "Surge" tank, or a header tank,  or a = "make-up"=20 tank.  This tank,  whatever you want to call it,  = is used=20 to supply EFI pump(s) with a positive head of fuel. That is the = way the=20 system MUST be designed.  If you do it any other way,  = sooner=20 or later,  it will bite you on the backside. =20 Guaranteed!
 
There is another possibility in = a badly=20 designed fuel system. AIR lock. Having experienced it = myself,  an=20 air lock in the supply line is quite capable of reducing flow in = the=20 high pressure side of fuel supply.  I won't bore you with = specific=20 details,  but I have had it happen on more than one=20 occasion.
 
It will normally occur where = the fuel line=20 is higher than either the fuel rail or the injector = supply.  In=20 such cases,  it is imperative that a bleed nipple is = installed to=20 bleed out any air.  This will be most evidenty where there = is no=20 fuel return.  My personal opinion is that anybody that runs = an EFI=20 system without a proper fuel return is just asking for it.  = A fuel=20 return will assist,  but will not necessarily eliminate an = air lock=20 in the fuel supply.
 
There is a minimum system = configuration=20 complexity in any EFI system,  below which,  if = you try=20 to simplify it any further,  can cause problems under = certain=20 conditions.  I KNOW that many current model cas have = returnless=20 fuel sustems,  but the design is quite complex,  and = unless=20 you understand the differences,  you will not be able to = implement=20 such a system.
 
 
----- Original Message ----- =
From:=20 al p = wick=20
To: Rotary motors in = aircraft=20
Sent: Sunday, June 12, = 2005 4:39=20 PM
Subject: [FlyRotary] Re: = Is common=20 sense dead (rant mode on)

 
On Sat, 11 Jun 2005 21:48:53 -0500 "rijakits" <rijakits@cwpanama.net>=20 writes:
Everyone here is = interested in=20 solutions, SPECIFIC solutions.
 
 
 
Specifically, Follow this general principal:
When you have a theory, find way to prove it's true. Use = facts.=20
 
Example:
I think my fuel system is not going to vapor = lock.
 
Measure it. Place pressure gage on the fuel inlet to the = pump.=20 There is direct correlation of INLET pressure to vapor = lock=20 risk. Measure the pressure and compare to other aircraft. If you = have=20 unusual aircraft, also measure with nose down, nose up.
 
Get a coffee can of fuel. Have one person in your group = measure the=20 pressure change while adjusting the following:
Pump temp.
head pressure.
reduced atmospheric pressure on tank
inlet filter
Fuel type
 
This info provides perspective as to how significant each = is. It=20 can be tested easily with coffee can.
The result: the entire group has lower risk because they = can=20 measure how close they are to vapor lock when ground testing. =
 
 
-al
 
 
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