From: "Steven W. Boese" <flyrotary@lancaironline.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Fuel Pump current and pressures
Thread-Topic: [FlyRotary] Re: Fuel Pump current and pressures
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Date: Fri, 24 Mar 2017 19:11:26 +0000
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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 spec=
ulation.  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 returnin=
g 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 en=
gine 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/h=
r 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 high=
er 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<ma=
ilto:flyrotary@lancaironline.net>> wrote:

Have you tried swapping the position of the pumps & making the same measure=
ments? 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 le=
ft. I couldn't guess how much, but that would account for at least some pre=
ssure increase.

Charlie

On Fri, Mar 24, 2017 at 4:14 AM, steve Izett <flyrotary@lancaironline.net<m=
ailto: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 ra=
il 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 pres=
sure
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=92t have data of fuel pressure under load to see if it drops as powe=
r is applied)
I think I modelled the pump layout/manifold after seeing someone else=92s a=
nd not sure if it causes any problems?
The pumps came from eBay stating that they were genuine Walbro and now I=92=
m wondering.

Cheers

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


<Fuel Pres Pumps.JPG>


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<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3DWindows-1=
252">
<style type=3D"text/css" style=3D"display:none;"><!-- P {margin-top:0;margi=
n-bottom:0;} --></style>
</head>
<body dir=3D"ltr">
<div id=3D"divtagdefaultwrapper" style=3D"font-size:12pt;color:#000000;font=
-family:Calibri,Arial,Helvetica,sans-serif;" dir=3D"ltr">
<p>Steve,</p>
<p><br>
</p>
<p>Examining the Walbro pump specifications at:</p>
<p><a class=3D"OWAAutoLink" id=3D"LPlnk244141" href=3D"https://walbrofuelpu=
mps.com/walbro-gsl-series-universal-inline-fuel-pumps" previewremoved=3D"tr=
ue">https://walbrofuelpumps.com/walbro-gsl-series-universal-inline-fuel-pum=
ps</a></p>
and looking at the data for the individual pumps enables the following spec=
ulation.&nbsp; It is only speculation.<br>
<p><br>
</p>
<p>If&nbsp;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 a=
mps.&nbsp; If your engine could use 20 gal/hr, that would still leave 50 ga=
l/hr returning to the tank.&nbsp; With two of those
 pumps running at 65 psi &nbsp;<br>
</p>
<div>they should be moving 60 gal/hr each with each drawing 10 amps.&nbsp; =
If your engine was using 20 gal/hr, 100 gal/hr would be returning to the ta=
nk.&nbsp; This would seem to be moving much more fuel than necessary.&nbsp;=
 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=
.&nbsp;</div>
<div><br>
</div>
<div>At these flow rates, your whole fuel system could be&nbsp;a constricti=
on and any fittings (tee's etc) may have significant effects.</div>
<div><br>
</div>
<div>That is why it would be good to establish which pumps you are using ei=
ther by identifying them or measuring their flow rates.&nbsp; GSL393&nbsp; =
pumps
<span>(45 gal/hr at 40 psi and 5 amps)</span> might be more appropriate for=
 your installation if your present&nbsp;pumps have high flow ratings.</div>
<div><br>
</div>
<div>Steve Boese<br>
<br>
</div>
<div style=3D"color: rgb(0, 0, 0);">
<hr tabindex=3D"-1" style=3D"display:inline-block; width:98%">
<div id=3D"divRplyFwdMsg" dir=3D"ltr"><font color=3D"#000000" face=3D"Calib=
ri, sans-serif" style=3D"font-size:11pt"><b>From:</b> Rotary motors in airc=
raft &lt;flyrotary@lancaironline.net&gt; on behalf of Charlie England &lt;f=
lyrotary@lancaironline.net&gt;<br>
<b>Sent:</b> Friday, March 24, 2017 12:24 PM<br>
<b>To:</b> Rotary motors in aircraft<br>
<b>Subject:</b> [FlyRotary] Re: Fuel Pump current and pressures</font>
<div>&nbsp;</div>
</div>
<div>
<div class=3D"moz-cite-prefix">Hey Steve, <br>
<br>
Just re-read your post with the measurements, &amp; I'm not sure which had =
higher current draw. It was the bottom pump, right?<br>
<br>
Thanks,<br>
<br>
Charlie<br>
<br>
On 3/24/2017 8:06 AM, Stephen Izett wrote:<br>
</div>
<blockquote type=3D"cite">Good idea Charlie.&nbsp;
<div>That would clear it up as far as the manifold flow characteristics.
<div>Just a pain in the but to get to.</div>
<div>Thanks</div>
<div>Steve</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
<div>
<blockquote type=3D"cite">
<div>On 24 Mar 2017, at 8:56 pm, Charlie England &lt;<a href=3D"mailto:flyr=
otary@lancaironline.net">flyrotary@lancaironline.net</a>&gt; wrote:</div>
<br class=3D"Apple-interchange-newline">
<div>
<div dir=3D"ltr">Have you tried swapping the position of the pumps &amp; ma=
king the same measurements? It's hard to imagine it making that much differ=
ence, but the bottom pump does have a tight right turn and then a sharp edg=
ed 'T' turn to the left. I couldn't guess
 how much, but that would account for at least some pressure increase.&nbsp=
;
<div><br>
</div>
<div>Charlie</div>
</div>
<div class=3D"gmail_extra"><br>
<div class=3D"gmail_quote">On Fri, Mar 24, 2017 at 4:14 AM, steve Izett <sp=
an dir=3D"ltr">
&lt;<a href=3D"mailto:flyrotary@lancaironline.net" target=3D"_blank">flyrot=
ary@lancaironline.net</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0=0A=
                      .8ex; border-left:1px #ccc solid; padding-left:1ex">
<div style=3D"word-wrap:break-word">Hi Guys
<div>Hi Peoples</div>
<div><br>
</div>
<div>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.</div>
<div>Fuel then passes through the firewall and race filter before feeding t=
he rail and returning via the pressure regulator (4cyl toyota reg)&nbsp;</d=
iv>
<div>back through the firewall to the header tank, again in 3/8.</div>
<div><br>
</div>
<div>I did further measurements today.&nbsp;</div>
<div><br>
</div>
<div>1. Bottom Pump only&nbsp;~8A and 48psi - Turning both pumps on this pu=
mp draws 9.9A and produces a rail pressure of 65psi</div>
<div>2. Bottom Pump only&nbsp;~9.9A and 44psi - Turning both pumps on this =
pump draws 14.8A and produces the same rail pressure of 65psi</div>
<div><br>
</div>
<div>So bottom pump goes from 8.0 -&gt; 9.9A (1.9A increase) under higher h=
ead pressure</div>
<div>Top pump goes from 9.9A -&gt; 14.8A (5.1A increase) under same head!!<=
/div>
<div><br>
</div>
<div>Clearly Pressure Reg bypass capacity is inadequate for both pumps, per=
haps with even one pump running.&nbsp;</div>
<div>(I don=92t have data of fuel pressure under load to see if it drops as=
 power is applied)</div>
<div>I think I modelled the pump layout/manifold after seeing someone else=
=92s and not sure if it causes any problems?</div>
<div>The pumps came from eBay stating that they were genuine Walbro and now=
 I=92m wondering.</div>
<div><br>
</div>
<div>Cheers</div>
<div><br>
</div>
<div>Steve Izett</div>
<div>Glasair Super II RG Renesis 4 port RD1C EC3 EM3&nbsp;</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><span id=3D"cid:BBF116C9-ED31-4AF9-836B-80EC26979DA9">&lt;Fuel Pres Pu=
mps.JPG&gt;</span></div>
</div>
</blockquote>
</div>
<br>
</div>
</div>
</blockquote>
</div>
<br>
</div>
</div>
</blockquote>
<br>
</div>
</div>
</div>
</body>
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