X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-iy0-f180.google.com ([209.85.210.180] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTPS id 5110100 for flyrotary@lancaironline.net; Wed, 31 Aug 2011 23:26:15 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.210.180; envelope-from=fluffysheap@gmail.com Received: by iabz7 with SMTP id z7so2460175iab.25 for ; Wed, 31 Aug 2011 20:25:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=L7yJFQByFz/z8xxkGUIfnSih5N4xCuvE3WORUn2v5eI=; b=sXS96xtiyUbMX9dpYLWvcniGtpP+T7QGxmKLOJhWdThN81Bb1laFZ3Hl+WSpt+raL/ R/X4o4P2UYLYn1UuVjDSwyiCeYVrXODiHNSr4wlm3efug5py8ErGDRk5CCcY1+49C6/T TJGT4PnlX70Vc3jm2/DgTFAdXUEF/ll381GGY= MIME-Version: 1.0 Received: by 10.231.28.206 with SMTP id n14mr2264564ibc.13.1314847541100; Wed, 31 Aug 2011 20:25:41 -0700 (PDT) Received: by 10.231.162.67 with HTTP; Wed, 31 Aug 2011 20:25:40 -0700 (PDT) In-Reply-To: References: Date: Wed, 31 Aug 2011 21:25:40 -0600 Message-ID: Subject: Re: [FlyRotary] Re: CG Products Intake Manifold From: William Wilson To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=00151773df6a9f014304abd8cc76 --00151773df6a9f014304abd8cc76 Content-Type: text/plain; charset=ISO-8859-1 Vapor lock does not happen in the fuel rail or anyplace downstream of the fuel pump. It happens in the fuel pump inlet. The main thing that matters for vapor lock is how far and how high the pump has to suck fuel. Altitude can matter, but will not unless you are dangerously close to the critical pressure in the first place. If altitude makes your fuel boil, you were within 10-15 degrees F of it boiling anyway. Pulsation dampers are a fire hazard and should never be used. Good quality pressure regulators will incorporate similar capabilities. Typically, the fuel rail will be in between the pump and the pressure regulator. The output of the pressure regulator should be to the tank. You can think of the return line to the tank as being essentially a free flowing, no resistance path, so you can't build any pressure in that part of the system. If the fuel rail were after the pressure regulator, you would have little to no pressure in the fuel rail - all the fuel would just flow back into the tank. Things change in a returnless system. In a returnless system, obviously, there's no return line to let the pressure out. The capacity of the pump far exceeds the maximum flow of the injectors which is the only way out for the fuel. So you can build a regulator which will maintain the appropriate pressure in the downstream area. The drawback, at least for a rotary, is that you would always have pressure in the fuel rail, and leaky injectors can then cause flooding. On Wed, Aug 31, 2011 at 6:35 AM, wrote: > ** > Interesting Chad. > The people flying Subes and using autogas were also guessing that altitude > was a factor in vaporlock. We won't be using autogas due to variable > formulation eating up epoxy tanks. > We were thinking that if the regulator was the last item in the chain and > that the rails were hooked up serially that it would minimize vaporlock and > also a few seconds of the pump running before a hot restart would cool and > clear the rail. > > Chrissi & Randi > www.CozyGirrrl.com > CG Products, Custom Aircraft Hardware > Chairwomen, Sun-N-Fun Engine Workshop > > In a message dated 8/30/2011 11:36:05 P.M. Central Daylight Time, > crobinson@medialantern.com writes: > > I recently researched EFI regulation a bit and found something interesting. > Many modern (post-1995) vehicles have "returnless" EDI systems where the > regulator is in or near the tank, not the engine compartment. > > It turns out this isn't for complexity reasons, though it does save a bit. > It's for emissions. The heating of the fuel in the engine compartment > transfers heat back to the tank. The tank's emissions do count even though > they're not huge. It's also one less part, hose, and set of fittings to > fail- and get warranty calls on. > > To deal with vapor lock they just crank up the pressure to 65 or more psi. > Very effective. > > Not at all saying we should do the same, but the purpose is interesting, > no? As well as the vapor lock" solution"... > > Regards, > Chad > > --00151773df6a9f014304abd8cc76 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Vapor lock does not happen in the fuel rail or anyplace downstream of the f= uel pump.=A0 It happens in the fuel pump inlet.=A0
The main thing that = matters for vapor lock is how far and how high the pump has to suck fuel.= =A0 Altitude can matter, but will not unless you are dangerously close to t= he critical pressure in the first place.=A0 If altitude makes your fuel boi= l, you were within 10-15 degrees F of it boiling anyway.

Pulsation dampers are a fire hazard and should never be used.=A0 Good q= uality pressure regulators will incorporate similar capabilities.=A0 Typica= lly, the fuel rail will be in between the pump and the pressure regulator.= =A0 The output of the pressure regulator should be to the tank.=A0 You can = think of the return line to the tank as being essentially a free flowing, n= o resistance path, so you can't build any pressure in that part of the = system.=A0 If the fuel rail were after the pressure regulator, you would ha= ve little to no pressure in the fuel rail - all the fuel would just flow ba= ck into the tank.

Things change in a returnless system.=A0 In a returnless system, obviou= sly, there's no return line to let the pressure out.=A0 The capacity of= the pump far exceeds the maximum flow of the injectors which is the only w= ay out for the fuel.=A0 So you can build a regulator which will maintain th= e appropriate pressure in the downstream area.=A0 The drawback, at least fo= r a rotary, is that you would always have pressure in the fuel rail, and le= aky injectors can then cause flooding.

On Wed, Aug 31, 2011 at 6:35 AM, <CozyGirrrl@aol.com&g= t; wrote:
Interesting Chad.
The people flying Subes and using autogas were also guessing that alti= tude=20 was a factor in vaporlock. We won't be using autogas due to variable fo= rmulation=20 eating up epoxy tanks.
We were thinking that if the regulator was the last item in the chain = and=20 that the rails were hooked up serially that it would minimize vaporlock and= also=20 a few seconds of the pump running before a hot restart would cool and clear= the=20 rail.
=A0
Chrissi &= amp;=20 Randi
www.CozyG= irrrl.com
CG=20 Products, Custom Aircraft Hardware
Chairwomen, Sun-N-Fun Engine Workshop=
=A0
In a message dated 8/30/2011 11:36:05 P.M. Central Daylight Time,=20 crobinson@m= edialantern.com writes:

I recently researched EFI regulation a bit and found something interes= ting.=20 Many modern (post-1995) vehicles have "returnless" EDI systems = where the=20 regulator is in or near the tank, not the engine compartment.

It turns out this isn't for complexity reasons, though it does sav= e a bit.=20 It's for emissions. The heating of the fuel in the engine compartment= =20 transfers heat back to the tank. The tank's emissions do count even t= hough=20 they're not huge. It's also one less part, hose, and set of fitti= ngs to=20 fail-=A0 and get warranty calls on.

To deal with vapor lock they just crank up the pressure to 65 or more = psi.=20 Very effective.

Not at all saying we should do the same, but the purpose is interestin= g,=20 no? As well as the vapor lock" solution"...

Regards,
Chad


--00151773df6a9f014304abd8cc76--