X-Virus-Scanned: clean according to Sophos on Logan.com From: "steve Izett" Received: from mail-pf0-f175.google.com ([209.85.192.175] verified) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9606880 for flyrotary@lancaironline.net; Fri, 24 Mar 2017 20:19:44 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.192.175; envelope-from=steveize@gmail.com Received: by mail-pf0-f175.google.com with SMTP id p189so2228962pfp.1 for ; Fri, 24 Mar 2017 17:19:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:mime-version:subject:date:references:to:in-reply-to:message-id; bh=hnKg2+n/yBuMTzFDLK3RX/C64Tv3qOQss8uud/kF7OU=; b=pZ4VTyLcK+nGZ9d4wZtoVZogIvQMXFoG/La7mKfr4undbUjxd+PrbITD+G15fiGdDr Xrey+YCWkBWx/XszE+b8EkrqgUd6VJIG4KsQn9UoCheaEnv9Mzf25Ka6lhUT1I3e0HhX n+06qakDEbIOWLJk0brstGJa0CU4Gab495kd968yaQ0WAWBW6KaCfPl3mDR3UtqHZxKL Ya4qoDO2a+ZpgLwthYZcF1zi31jOX7piG+KYXfMvMIlEnQcRJHmuDIlfWQ0hvmpaHpNf HZrOcXh18NVWj9gMbVxeoDsxcBeUh19gv071b9WqS4YUMZDS5llDYTZeCmp/+hZSBIef oT0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:mime-version:subject:date:references:to :in-reply-to:message-id; bh=hnKg2+n/yBuMTzFDLK3RX/C64Tv3qOQss8uud/kF7OU=; b=RS5YGxYcwg46ayceNFf54InLHEmiD2LDMaGvan++hqa2L206EuQEVk4X6juvr3kDK2 HM454o3Fc3oil5ArkNAbLOQWno5O7lJW4gfmUkQ520qwbRhlkAP4orNjsNFmWZ3WQvWB uq1YoW4C2rNeEhCp5xDw92IvpTAxVrkkuvmQurxnfXKOECcgu81n5jYTGcjy/xGERRFX ASGpdqiEOcBAshi/8+apkb1zqkPVrFE2akM6arPGdB0ahtsb5gRV+muS3iu1fvrw6CXp Lt145I4cjFGp4tEq8E3isGA/Aco9xuXzQFp3unogSXLgZ76imLc8BMy2eW5/+XNRJvmH mPJg== X-Gm-Message-State: AFeK/H0079e9REkNLJKl535fFZX2W4McE+YtCSf7WFG8CDRPl0LPTulFcUrJBTpuEzYSdA== X-Received: by 10.84.210.107 with SMTP id z98mr14564289plh.11.1490401168417; Fri, 24 Mar 2017 17:19:28 -0700 (PDT) Return-Path: Received: from [10.1.1.6] ([124.169.71.123]) by smtp.gmail.com with ESMTPSA id 198sm6689395pgb.51.2017.03.24.17.19.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 Mar 2017 17:19:27 -0700 (PDT) Content-Type: multipart/alternative; boundary="Apple-Mail=_3415E511-A26A-4637-A268-049D09B490F2" Mime-Version: 1.0 (Mac OS X Mail 10.2 \(3259\)) Subject: Re: [FlyRotary] Re: Fuel Pump current and pressures Date: Sat, 25 Mar 2017 08:19:23 +0800 References: To: Rotary motors in aircraft In-Reply-To: Message-Id: <7DD7AE88-A71A-43A2-AA63-52255191C6EB@gmail.com> X-Mailer: Apple Mail (2.3259) --Apple-Mail=_3415E511-A26A-4637-A268-049D09B490F2 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 I=E2=80=99ll remove the pumps to confirm the model and do some testing. In old notes I see I thought they were GSL392=E2=80=99s. The real obvious is as you show in your calcs, the volume of fuel = heading back to the tank with both pumps running is huge. With a piddly little 150hp stock unit that probably has quite a small = orifice for bypassing regulation, quite large pressures are going to = build up. I have the two problems though. 1. Flow capacity of the regulator if I want to be able to run both pumps = simultaneously. 2. The difference between the pumps currently. Why does one draw more = current and produce less pressure? What is causing the 4psi pressure differential: One of the pumps draws more current but the pressure has dropped from 48 = to 44psi. Now either one of two things could bring this about in my = thinking. A. The higher current pump is delivering very low fuel flow and so = measures a rail pressure drop, meaning not enough fuel pressure/flow to = break the regulator seat. But I think I can remember hearing fuel = returning to the tank when either pump is running. OR B. The other pump is delivering at idle more fuel pressure/flow than the = the regulator can cope with so is higher than the regulation pressure. = So as the engine begins to use fuel the rail pressure would drop back to = the regulator pressure. (I cant remember seeing this during engine = testing, but I wasn=E2=80=99t looking for it and Ive deleted some video = of engine monitoring). Have I missed something? Steve > On 25 Mar 2017, at 3:11 am, Steven W. Boese = wrote: >=20 > Steve, >=20 > Examining the Walbro pump specifications at: > = https://walbrofuelpumps.com/walbro-gsl-series-universal-inline-fuel-pumps = and looking at the data for the individual pumps enables the following = speculation. It is only speculation. >=20 > If you have GSL392 pumps, as are almost all of the pumps listed now on = Ebay, they have a flow rating of 255 L/hr (70 gal/hr) at 40 psi and 8 = amps. If your engine could use 20 gal/hr, that would still leave 50 = gal/hr returning to the tank. With two of those pumps running at 65 psi = =20 > they should be moving 60 gal/hr each with each drawing 10 amps. If = your engine was using 20 gal/hr, 100 gal/hr would be returning to the = tank. This would seem to be moving much more fuel than necessary. = Depending on where you are measuring the fuel pressure and the details = of the fuel flow path, the pressure at the pump outlet (and the current = draw) could be much higher with flow rates this high.=20 >=20 > At these flow rates, your whole fuel system could be a constriction = and any fittings (tee's etc) may have significant effects. >=20 > That is why it would be good to establish which pumps you are using = either by identifying them or measuring their flow rates. GSL393 pumps = (45 gal/hr at 40 psi and 5 amps) might be more appropriate for your = installation if your present pumps have high flow ratings. >=20 > Steve Boese >=20 > From: Rotary motors in aircraft > on behalf of Charlie England = > > Sent: Friday, March 24, 2017 12:24 PM > To: Rotary motors in aircraft > Subject: [FlyRotary] Re: Fuel Pump current and pressures > =20 > Hey Steve,=20 >=20 > Just re-read your post with the measurements, & I'm not sure which had = higher current draw. It was the bottom pump, right? >=20 > Thanks, >=20 > Charlie >=20 > On 3/24/2017 8:06 AM, Stephen Izett wrote: >> Good idea Charlie.=20 >> That would clear it up as far as the manifold flow characteristics. >> Just a pain in the but to get to. >> Thanks >> Steve >>=20 >>=20 >>=20 >>> On 24 Mar 2017, at 8:56 pm, Charlie England = > = wrote: >>>=20 >>> Have you tried swapping the position of the pumps & making the same = measurements? It's hard to imagine it making that much difference, but = the bottom pump does have a tight right turn and then a sharp edged 'T' = turn to the left. I couldn't guess how much, but that would account for = at least some pressure increase.=20 >>>=20 >>> Charlie >>>=20 >>> On Fri, Mar 24, 2017 at 4:14 AM, steve Izett = > = wrote: >>> Hi Guys >>> Hi Peoples >>>=20 >>> Here is a photo of our parallel pumps plumbed with 3/8 aluminium = lines feed from a 28 gallon header tank above to the right. >>> Fuel then passes through the firewall and race filter before feeding = the rail and returning via the pressure regulator (4cyl toyota reg)=20 >>> back through the firewall to the header tank, again in 3/8. >>>=20 >>> I did further measurements today.=20 >>>=20 >>> 1. Bottom Pump only ~8A and 48psi - Turning both pumps on this pump = draws 9.9A and produces a rail pressure of 65psi >>> 2. Bottom Pump only ~9.9A and 44psi - Turning both pumps on this = pump draws 14.8A and produces the same rail pressure of 65psi >>>=20 >>> So bottom pump goes from 8.0 -> 9.9A (1.9A increase) under higher = head pressure >>> Top pump goes from 9.9A -> 14.8A (5.1A increase) under same head!! >>>=20 >>> Clearly Pressure Reg bypass capacity is inadequate for both pumps, = perhaps with even one pump running.=20 >>> (I don=E2=80=99t have data of fuel pressure under load to see if it = drops as power is applied) >>> I think I modelled the pump layout/manifold after seeing someone = else=E2=80=99s and not sure if it causes any problems? >>> The pumps came from eBay stating that they were genuine Walbro and = now I=E2=80=99m wondering. >>>=20 >>> Cheers >>>=20 >>> Steve Izett >>> Glasair Super II RG Renesis 4 port RD1C EC3 EM3=20 >>>=20 >>>=20 >>>=20 >>>=20 >>>=20 >>> --Apple-Mail=_3415E511-A26A-4637-A268-049D09B490F2 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 I=E2=80=99ll remove the pumps to confirm the model and do = some testing.
In old notes I see I thought they were = GSL392=E2=80=99s.
The real obvious is as you show = in your calcs, the volume of fuel heading back to the tank with both = pumps running is huge.
With a piddly little 150hp = stock unit that probably has quite a small orifice for bypassing = regulation, quite large pressures are going to build up.
I have the two problems though.
1. Flow = capacity of the regulator if I want to be able to run both pumps = simultaneously.
2. The difference between the pumps = currently. Why does one draw more current and produce less = pressure?

What = is causing the 4psi pressure differential:
One of = the pumps draws more current but the pressure has dropped from 48 to = 44psi. Now either one of two things could bring this about in my = thinking.
A. The higher current pump is delivering = very low fuel flow and so measures a rail pressure drop, meaning not = enough fuel pressure/flow to break the regulator seat. But I think I can = remember hearing fuel returning to the tank when either pump is running. = OR
B. The other pump is delivering at idle more = fuel pressure/flow than the the regulator can cope with so is higher = than the regulation pressure. So as the engine begins to use fuel the = rail pressure would drop back to the regulator pressure. (I cant = remember seeing this during engine testing, but I wasn=E2=80=99t looking = for it and Ive deleted some video of engine monitoring).

Have I missed = something?

Steve
On 25 Mar 2017, at 3:11 am, Steven W. Boese = <flyrotary@lancaironline.net> wrote:

Steve,

Examining the = Walbro pump specifications at:
https://walbrofuelpumps.com/walbro-gsl-series-univ= ersal-inline-fuel-pumps
and looking at the data for the = individual pumps enables the following speculation.  It is only = speculation.

If you have GSL392 pumps, as are = almost all of the pumps listed now on Ebay, they have a flow rating of = 255 L/hr (70 gal/hr) at 40 psi and 8 amps.  If your engine could = use 20 gal/hr, that would still leave 50 gal/hr returning to the = tank.  With two of those pumps running at 65 psi  
they should be moving 60 gal/hr each = with each drawing 10 amps.  If your engine was using 20 gal/hr, 100 = gal/hr would be returning to the tank.  This would seem to be = moving much more fuel than necessary.  Depending on where you are = measuring the fuel pressure and the details of the fuel flow path, the = pressure at the pump outlet (and the current draw) could be much higher = with flow rates this high. 

At these flow rates, your whole fuel = system could be a constriction and any fittings (tee's etc) may = have significant effects.

That is why it would be good to establish which pumps you are = using either by identifying them or measuring their flow rates.  = GSL393  pumps (45 gal/hr at 40 psi and 5 amps) might be more appropriate = for your installation if your present pumps have high flow = ratings.

Steve = Boese

From: Rotary motors in aircraft = <flyrotary@lancaironline.net> on behalf of Charlie = England <flyrotary@lancaironline.net>
Sent: Friday, March 24, 2017 = 12:24 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: Fuel Pump = current and pressures
 
Hey Steve, 

Just re-read your post with the measurements, & I'm not = sure which had higher current draw. It was the bottom pump, right?

Thanks,

Charlie

On 3/24/2017 8:06 AM, Stephen Izett wrote:
Good idea = Charlie. 
That would clear it up as far as the = manifold flow characteristics.
Just a pain in the but to = get to.
Thanks
Steve



On 24 Mar 2017, at 8:56 pm, Charlie England = <flyrotary@lancaironline.net> wrote:

Have you tried swapping the position of the pumps & = making the same measurements? It's hard to imagine it making that much = difference, but the bottom pump does have a tight right turn and then a = sharp edged 'T' turn to the left. I couldn't guess how much, but that = would account for at least some pressure increase. 

Charlie

On Fri, = Mar 24, 2017 at 4:14 AM, steve Izett <flyrotary@lancaironline.net> wrote:
Hi Guys
Hi = Peoples

Here = is a photo of our parallel pumps plumbed with 3/8 aluminium lines feed = from a 28 gallon header tank above to the right.
Fuel= then passes through the firewall and race filter before feeding the = rail and returning via the pressure regulator (4cyl toyota = reg) 
back through the firewall to the header = tank, again in 3/8.

I did further measurements today. 

1. Bottom Pump = only ~8A and 48psi - Turning both pumps on this pump draws 9.9A and = produces a rail pressure of 65psi
2. Bottom Pump = only ~9.9A and 44psi - Turning both pumps on this pump draws 14.8A = and produces the same rail pressure of 65psi

So bottom pump goes from 8.0 -> 9.9A = (1.9A increase) under higher head pressure
Top pump = goes from 9.9A -> 14.8A (5.1A increase) under same head!!

Clearly Pressure Reg = bypass capacity is inadequate for both pumps, perhaps with even one pump = running. 
(I don=E2=80=99t have data of fuel = pressure under load to see if it drops as power is applied)
I think I modelled the pump layout/manifold after seeing = someone else=E2=80=99s and not sure if it causes any problems?
The pumps came from eBay stating that they were genuine = Walbro and now I=E2=80=99m wondering.

Cheers

Steve Izett
Glasair = Super II RG Renesis 4 port RD1C EC3 EM3 





<Fuel Pres = Pumps.JPG>

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