X-Virus-Scanned: clean according to Sophos on Logan.com From: "Stephen Izett" Received: from mail-pg0-f47.google.com ([74.125.83.47] verified) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9608417 for flyrotary@lancaironline.net; Sat, 25 Mar 2017 10:49:56 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.83.47; envelope-from=steveize@gmail.com Received: by mail-pg0-f47.google.com with SMTP id t143so8591361pgb.2 for ; Sat, 25 Mar 2017 07:49:56 -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=7TCiTL2DwMhSJY0a+gTM0nvEj/tNbRjF7dvIaX4ZgMs=; b=JW487Z5tHI757TqbuBvefnCpjQ9uQgDg6kdeive0iKn+rLO67HNNXue/0m2ORWDxzw 96/gbclstYH2WlKbPxQITi960TVKO2go9aQm64CgfxPxklfdbn+GLmeL5P29GTSyZYm9 h33sSxJq0IT/Djrtzlx7RS7HdUkLNHPB3vfjTqFU4+OgV1zySoDJ/jFvAp1IZIJntEx6 UWnduw7p7F+Db3/wWjQE4AD++8AzZmmAkjwqBhfsAN95/XvIW8bZvyMlks7ArsaBZwa7 4FTIhG1pwc7QvOk6AIcDrjb1B3qAGKejpFtiNHcEj8ot6GlY7YRpuPBtF3wiT2ufX+EJ OdPQ== 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=7TCiTL2DwMhSJY0a+gTM0nvEj/tNbRjF7dvIaX4ZgMs=; b=XIR4O0+fGmLvH+DrHAotAvV/9lrCbnX0pxojYZn1FOC4j0dr316mXP1NAzjbMDZiwq tcgcw8iCxnbK+ru4XTjamsdmAzNWEQI1gMKYM4wUUT5etUPQ7jPw3nX289d8RKnNkdv9 gYunV3IerRFeVS9c1volij2cqshI1kDGpthyevbuDs3Exla+FzOvEyWZ2OKEbMuzRkEe ccYgkQV10InuKeF8l1UNaCoxmO8wMCCpy8NzJ4Vr7MzT1/3RJEv4++KQiLZWYtmD624a 3mtLJbrXoDYId7BEb1M1Fa4C5BAkDtMDVDYkTPGRCQQRRviwkTEx0AGmiYdRhLCiuS93 5X1w== X-Gm-Message-State: AFeK/H0YSQpgNtEWB+PdsI7VTqk5NPb/6kjj9gDEnhN/6hQiyRTnuooERNftv3xkh567gw== X-Received: by 10.99.67.1 with SMTP id q1mr15562503pga.210.1490453377887; Sat, 25 Mar 2017 07:49:37 -0700 (PDT) Return-Path: Received: from [10.1.1.6] ([124.169.71.123]) by smtp.gmail.com with ESMTPSA id y5sm11147766pfd.33.2017.03.25.07.49.35 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 25 Mar 2017 07:49:36 -0700 (PDT) X-Google-Original-From: Stephen Izett Content-Type: multipart/alternative; boundary="Apple-Mail=_47DE071C-A1A6-489B-938D-1CBDD7760DEB" 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 22:49:32 +0800 References: To: Rotary motors in aircraft In-Reply-To: Message-Id: <065B1AF2-5CFF-4236-853A-EDEC5A3CBC0E@icloud.com> X-Mailer: Apple Mail (2.3259) --Apple-Mail=_47DE071C-A1A6-489B-938D-1CBDD7760DEB Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Thanks Steve > On 25 Mar 2017, at 10:28 pm, Steven W. Boese = wrote: >=20 > Steve, > All I know is that pump was sold by Tracy and they have given me good = service. If others have had problems with them or are using different = pumps, maybe they will provide feedback. > Other pumps with similar specifications should work. > I do know that the stock RX7 in-tank pump has worked fine at up to 200 = hp on my test stand. >=20 > Steve Boese >=20 > On Mar 25, 2017, at 6:32 AM, steve Izett > wrote: >=20 >> Thanks Steve >> Really appreciate your helping me with this. >> Is there an option other than the Walbro GSL393 or is this the = recommended inline pump at present? >>=20 >> Thanks >> Steve >>=20 >>=20 >>=20 >>> On 25 Mar 2017, at 3:11 pm, Steven W. Boese = > = wrote: >>>=20 >>> Steve, >>>=20 >>> It is quite likely that getting your fuel system to behave would not = involve looking at more than can be seen in the photo of the pumps that = you posted. >>>=20 >>> Your item 1 would most likely be resolved if pumps of lower flow = ratings were used. The stock RX7 regulator is very similar to the one = you are using and has worked well with those smaller pumps. >>>=20 >>> Item 2 may be a result of the pump with the higher current draw = having more internal friction causing a load on the motor in addition to = the load from pumping fuel.=20 >>> The additional load would slow the motor down resulting in less flow = and lower pressure. It is possible that the decreased flow allows the = regulator to control the pressure at 44 psi. Otherwise there may be a = constriction either within the pump or in the flow path somewhere before = the point where the flow of the two pumps are combined. >>>=20 >>> Item A is unlikely to be the case since if the seat in the regulator = hadn't been broken, there would be no flow, thus stalling the pump and = causing a current draw of over 20 amps. >>>=20 >>> In item B, you are likely correct that the regulator cannot support = the flow from the high volume pump, thus causing the rail pressure to be = above the regulator's pressure rating. It seems unlikely, however, that = the pressure would drop with the engine running since there is so much = more fuel circulating through the system (~70 gal/hr) than what the = engine could ever use (~20 gal/hr) even at full throttle. >>>=20 >>> All this discussion is directed toward the pumps or the system = downstream of them. Consider also the system between the tank and the = pumps. Trying to draw 140 gal/hr with the two pumps through a single -6 = line, and also through a 20 to 40 micron screen if one is installed as = required by the pump manufacturer, would have to involve a very low = pressure at the inlet to the pumps. This seems to be a very good recipe = for vapor lock. >>>=20 >>> Steve Boese =20 >>>=20 >>>=20 >>> From: Rotary motors in aircraft > on behalf of steve Izett = > >>> Sent: Friday, March 24, 2017 6:19:23 PM >>> To: Rotary motors in aircraft >>> Subject: [FlyRotary] Re: Fuel Pump current and pressures >>> =20 >>> 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? >>>=20 >>> 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). >>>=20 >>> Have I missed something? >>>=20 >>> 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 >>>> =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 >>>>>> >>=20 --Apple-Mail=_47DE071C-A1A6-489B-938D-1CBDD7760DEB Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 Thanks Steve

On 25 Mar 2017, at 10:28 pm, = Steven W. Boese <flyrotary@lancaironline.net> wrote:

Steve,
All I know is that pump was sold by Tracy and they have = given me good service.  If others have had problems with them or = are using different pumps, maybe they will provide feedback.
Other pumps with similar specifications should = work.
I do know that the stock RX7 in-tank pump has worked = fine at up to 200 hp on my test stand.

Steve Boese

On Mar 25, 2017, at 6:32 AM, steve Izett <flyrotary@lancaironline.net> wrote:

Thanks Steve
Really appreciate your helping me with this.
Is there an option other than the Walbro GSL393 or is = this the recommended inline pump at present?

Thanks
Steve



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

Steve,

It is = quite likely that getting your fuel system to behave would not involve = looking at more than can be seen in the photo of the pumps that you = posted.

Your item = 1 would most likely be resolved if pumps of lower flow ratings were = used.  The stock RX7 regulator is very similar to the one you are = using and has worked well with those smaller pumps.

Item 2 = may be a result of the pump with the higher current draw having more = internal friction causing a load on the motor in addition to the load = from pumping fuel. 
The = additional load would slow the motor down resulting in less flow and = lower pressure.  It is possible that the decreased flow allows the = regulator to control the pressure at 44 psi.   Otherwise = there may be a constriction either within the pump or in the flow path = somewhere before the point where the flow of the two pumps are = combined.

Item A is = unlikely to be the case since if the seat in the regulator hadn't been = broken, there would be no flow, thus stalling the pump and causing a = current draw of over 20 amps.

In item = B, you are likely correct that the regulator cannot support = the flow from the high volume pump, thus causing the rail pressure to be = above the regulator's pressure rating.  It seems unlikely, however, that the pressure would drop with the engine running = since there is so much more fuel circulating through the system (~70 = gal/hr) than what the engine could ever use (~20 gal/hr) even at full = throttle.

All this = discussion is directed toward the pumps or the system downstream of = them.  Consider also the system between the tank and the = pumps.  Trying to draw 140 gal/hr with the two pumps through a = single -6 line, and also through a 20 to 40 micron screen if one is installed = as required by the pump manufacturer, would have to involve a very low = pressure at the inlet to the pumps.  This seems to be a very good = recipe for vapor lock.

Steve = Boese     


From: Rotary motors in aircraft = <flyrotary@lancaironline.net> on behalf of steve Izett <flyrotary@lancaironline.net>
Sent: Friday, March 24, 2017 = 6:19:23 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: Fuel Pump = current and pressures
 
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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