X-Virus-Scanned: clean according to Sophos on Logan.com From: "steve Izett" Received: from mail-pg0-f54.google.com ([74.125.83.54] verified) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9608021 for flyrotary@lancaironline.net; Sat, 25 Mar 2017 08:32:21 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.83.54; envelope-from=steveize@gmail.com Received: by mail-pg0-f54.google.com with SMTP id 21so7729319pgg.1 for ; Sat, 25 Mar 2017 05:32:20 -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=y9fXbVFaCPuVGK54f6KK+ScDw6fT6SehN0Bz+HXKalw=; b=U9WHDWlDdBlvjvv+TZTuHtMLeQDgdcx4Fc11qmW+NPzsV9thrvrCZ6VoeA75Mpk1y+ L1H9ZelZ58VAG+Z/pqicNmRXIcdWh16k2eaOXNYxXSYWvBDHZYpbOhwdazQKqUpNEe84 5t/Re8wOXXIRVTaahiMy3Mc0VaM9AXM4026dATbrTStBKu3t79YY3aw9tlsc11Ws233z L3tXCXDAxefsbJbtMaav/deF+JT1uJl0M9EECnUeosojzs4/kKFkN0/bgYfGMc7PCt9D 00okwBxmrlJTxkw0/fxDMCi7E9z/q9LmS+e3E6kAjsbJxaneXgg3HDR5vSbvJve1zr+9 Z9Gg== 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=y9fXbVFaCPuVGK54f6KK+ScDw6fT6SehN0Bz+HXKalw=; b=sQlNxtDdzNGtV7FHCxj0Df4uIOVsOnhI6WEluEfhv2S686p+ekRXKsrU2gGWLStH7S Oh9bw1+GDUI8zS9B90DvkAZcvMK1Z9r6MmeLG1/oPIzuH9TbvfBAez6ZfdOAZJgAo5Sf 09AVxwcmc+ydMAuxVtGew7pHEL20Yn4JMeXKiy4Vx540RhiLey5ELovWzebFfR2C9wtf zQ7V1T+i1n5msGd2jyh/Ila2Mm/DqHvTmcs/giTJJRkJP0kKor2MjeFAC9xRTNbfundk Ic2Re5xiJOJYU5PDxUNhpG0KF4ZSh7nQv+JwUWwa5Hx+tqY27mUaUWKfV9sWAEQVQVvt 6F+Q== X-Gm-Message-State: AFeK/H265PBGW85mIV8OQQFlhVx+wVVSLte7sHw/Yh8x/AKFk9S5l6a+2PaQpr49FqWabg== X-Received: by 10.84.148.134 with SMTP id k6mr17922449pla.128.1490445122091; Sat, 25 Mar 2017 05:32:02 -0700 (PDT) Return-Path: Received: from [10.1.1.6] ([124.169.71.123]) by smtp.gmail.com with ESMTPSA id b77sm10461684pfl.2.2017.03.25.05.31.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 25 Mar 2017 05:32:01 -0700 (PDT) Content-Type: multipart/alternative; boundary="Apple-Mail=_825356E8-4802-4EB6-8814-03E4ECB02AC9" 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 20:31:56 +0800 References: To: Rotary motors in aircraft In-Reply-To: Message-Id: <9A2127B2-122A-43F2-8908-6D4E30A25C75@gmail.com> X-Mailer: Apple Mail (2.3259) --Apple-Mail=_825356E8-4802-4EB6-8814-03E4ECB02AC9 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 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 = 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 >>>> --Apple-Mail=_825356E8-4802-4EB6-8814-03E4ECB02AC9 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 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>

= --Apple-Mail=_825356E8-4802-4EB6-8814-03E4ECB02AC9--