X-Virus-Scanned: clean according to Sophos on Logan.com From: "Charlie England" Received: from mail-pf0-f181.google.com ([209.85.192.181] verified) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9606023 for flyrotary@lancaironline.net; Fri, 24 Mar 2017 15:37:15 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.192.181; envelope-from=ceengland7@gmail.com Received: by mail-pf0-f181.google.com with SMTP id p189so5005793pfp.1 for ; Fri, 24 Mar 2017 12:37:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=01dJ7yr/JGHFelaRKtOtWpFflsWa6EmgHif/01FkFWg=; b=X9cffwZYWghznxy7afWacy+eQNpZfkWS5nQ+iqITrssWUnOsO+ROMXlhPinukkY+WG X7dm10F/5rFOsZNFlkUUqAxm3tTSYJsFCgfoNgvYcC92t4j7odwmiIaFZuIwfGpUbaOi iDtPUJ2xDkDtX7XNg3lu2cEEetO/6NtBkOBpDqQrgJKQqUkr4iHFsoiFq6qKIaQ8GPuo +XcfMsXS0rstmfU+zzVZWsR5uYgMNcOGMbPC1WSfzqA/+ZEyN9Vmk7DJblyyhae0chac 6lhiq5KeGictsCmJK6FPgzqYcWQfIZraACeX3FtMWYGBzWgNxlZkMLT1XXHMzGodiVIx AKBg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=01dJ7yr/JGHFelaRKtOtWpFflsWa6EmgHif/01FkFWg=; b=Ch044C2kiW+aBk2n8thMs2JM7pQhbLPPdq0FsEvjU+1jZq/itEP1PbfmRtBZgZgXis F8wdc4ana4muQRX4+qhGDlWO5zsb5+8vFsUrcZ4SFky2k7Y1h6EPtOIbPIrYaGqSXfJG uwg/zc0+T3Fq9v3Oaq1AWR+Wp7nSMRb9z5FEvZMmaF49SELjjeE0iTjymubz5w6/2yW0 k/y8SKIxSUD3Q9VV+43s20M0qTIpIrfYeE1GIKcN2sRX/6uH/F58YZ8ANhYpZpCmKWvg N5gAWX1srR7HmNY9BegaiMGrUfdfzhrblO3oGIo+z3kAFFAtkBOwoq9u8JBtJR8NalJo GS9w== X-Gm-Message-State: AFeK/H2zQRlQrn5HPH4DvVAcssSv0YHMF3Z6PVyjMhoNcyOGbbU4hhDMKITYFv24EIjxGUMl08rDvgIFxUZK/A== X-Received: by 10.99.42.78 with SMTP id q75mr10889434pgq.144.1490384216261; Fri, 24 Mar 2017 12:36:56 -0700 (PDT) MIME-Version: 1.0 Received: by 10.100.128.83 with HTTP; Fri, 24 Mar 2017 12:36:55 -0700 (PDT) In-Reply-To: References: Date: Fri, 24 Mar 2017 14:36:55 -0500 Message-ID: Subject: Re: [FlyRotary] Re: Fuel Pump current and pressures To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=001a114693daca09e7054b7f1df8 --001a114693daca09e7054b7f1df8 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Good point. The GSL393 (lower volume) is what RWS (Tracy) was selling before he retired. FWIW, I toyed with the idea of using electronic pump control (PWM) to eliminate the need for a mechanical regulator. I called Walbro's tech line & he said that we shouldn't use PWM (which is fine on turbine style pumps) with gerotor pumps because the constant square wave pulsed supply voltage 'hammers' on the gears in the pump & greatly reduces life. But he went on to say that it's perfectly ok to run the pump at lower voltage to reduce the flow. So it's possible to insert an adjustable DC power supply in the supply to lower its output. Not necessarily recommending this, since it might introduce other 'issues' (reliability being one), but there you go...= . Charlie On Fri, Mar 24, 2017 at 2:11 PM, Steven W. Boese < flyrotary@lancaironline.net> wrote: > Steve, > > > 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. > > > 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 flo= w > path, the pressure at the pump outlet (and the current draw) could be muc= h > 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 eithe= r > 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 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 > > 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 > 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 th= e > 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 > 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 draw= s >> 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 drop= s 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 >> >> >> >> >> >> >> > > > > --001a114693daca09e7054b7f1df8 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Good point. The GSL393 (lower volume) is what RWS (Tracy) = was selling before he retired.=C2=A0

FWIW, I toyed with = the idea of using electronic pump control (PWM) to eliminate the need for a= mechanical regulator. I called Walbro's tech line & he said that w= e shouldn't use PWM (which is fine on turbine style pumps) with gerotor= pumps because the constant square wave pulsed supply voltage 'hammers&= #39; on the gears in the pump & greatly reduces life. But he went on to= say that it's perfectly ok to run the pump at lower voltage to reduce = the flow. So it's possible to insert an adjustable DC power supply in t= he supply to lower its output. Not necessarily recommending this, since it = might introduce other 'issues' (reliability being one), but there y= ou go....

Charlie
On Fri, Mar 24, 2017 at 2:11 PM, Steven W. Boe= se <flyrotary@lancaironline.net> wrote:

Steve,


Examining the Walbro pump specifications at:

https://walbrofuelpumps.com/wa= lbro-gsl-series-universal-inline-fuel-pumps

and looking at the data for the individual pumps enables the following spec= ulation.=C2=A0 It is only speculation.


If=C2=A0you 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 a= mps.=C2=A0 If your engine could use 20 gal/hr, that would still leave 50 ga= l/hr returning to the tank.=C2=A0 With two of those pumps running at 65 psi =C2=A0

they should be moving 60 gal/hr each with each drawing 10 amps.=C2=A0 = If your engine was using 20 gal/hr, 100 gal/hr would be returning to the ta= nk.=C2=A0 This would seem to be moving much more fuel than necessary.=C2=A0= Depending on where you are measuring the fuel pressure and the details of the fuel flow path, the pressure at the pump o= utlet (and the current draw) could be much higher with flow rates this high= .=C2=A0

At these flow rates, your whole fuel system could be=C2=A0a constricti= on and any fittings (tee's etc) may have significant effects.

That is why it would be good to establish which pumps you are using ei= ther by identifying them or measuring their flow rates.=C2=A0 GSL393=C2=A0 = pumps (45 gal/hr at 40 psi and 5 amps) might be more appropriate for= your installation if your present=C2=A0pumps have high flow ratings.

Steve Boese

From: = Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Charli= e 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
=C2=A0
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.=C2=A0
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&= gt; wrote:

Have you tried swapping the position of the pumps & ma= king the same measurements? It's hard to imagine it making that much di= fference, 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.=C2= =A0

Charlie

On Fri, Mar 24, 2017 at 4:14 AM, steve Izett <flyrot= ary@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 t= he rail and returning via the pressure regulator (4cyl toyota reg)=C2=A0
back through the firewall to the header tank, again in 3/8.

I did further measurements today.=C2=A0

1. Bottom Pump only=C2=A0~8A and 48psi - Turning both pumps on this pu= mp draws 9.9A and produces a rail pressure of 65psi
2. Bottom Pump only=C2=A0~9.9A 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 h= ead pressure
Top pump goes from 9.9A -> 14.8A (5.1A increase) under same head!!<= /div>

Clearly Pressure Reg bypass capacity is inadequate for both pumps, per= haps with even one pump running.=C2=A0
(I don=E2=80=99t have data of fuel pressure under load to see if it dr= ops 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=C2=A0





<Fuel Pres Pumps.JPG>




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