X-Virus-Scanned: clean according to Sophos on Logan.com From: "Steven W. Boese" Received: from [104.47.36.116] (HELO NAM02-SN1-obe.outbound.protection.outlook.com) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9607429 for flyrotary@lancaironline.net; Sat, 25 Mar 2017 03:11:45 -0400 Received-SPF: none receiver=logan.com; client-ip=104.47.36.116; envelope-from=SBoese@uwyo.edu DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uwy.onmicrosoft.com; s=selector1-uwyo-edu; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version; bh=03lfrzpzEnaTr/WkdRfqlUuZ9Yo/XL9kTUvGhUxonH4=; b=Q2h5mLb35uxcZyUkSxHaUMPBQoOD6yO0UpOvTR4OcQD27Z30b2vPORC0EDlKGJ0mal2foFru5LQUpP+FXkj0PbBUZhFZB/y7jTHj2mCn/z1Mw7G4I7gOK1oLMHYnDts8m8+OLUxX4yq4ifA5OF74JvPiU0wFGHoIyuik5X/BdTQ= Received: from CO2PR0501MB903.namprd05.prod.outlook.com (10.141.247.18) by CO2PR0501MB901.namprd05.prod.outlook.com (10.141.247.16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.991.4; Sat, 25 Mar 2017 07:11:26 +0000 Received: from CO2PR0501MB903.namprd05.prod.outlook.com ([10.141.247.18]) by CO2PR0501MB903.namprd05.prod.outlook.com ([10.141.247.18]) with mapi id 15.01.0991.018; Sat, 25 Mar 2017 07:11:26 +0000 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Fuel Pump current and pressures Thread-Topic: [FlyRotary] Re: Fuel Pump current and pressures Thread-Index: AQHSpP2qperZX1lzNkaaODOzrKAaN6GlFQ3t Date: Sat, 25 Mar 2017 07:11:26 +0000 Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: lancaironline.net; dkim=none (message not signed) header.d=none;lancaironline.net; dmarc=none action=none header.from=uwyo.edu; x-originating-ip: [69.146.90.23] x-microsoft-exchange-diagnostics: 1;CO2PR0501MB901;7:ngEWNHj58/hiL3esdK2ihNhNyTudXUjNZ4xeTcjMYA5dFNwExZDQxpFvP4L8hXfO1h7RB41Sw5Tolvup5/BtcTg73PUK++jdlSci20zcFc1ucrwbgtgkFmnG79/TWmfBQ3A4WW3mYthhnPapugBcv2XkEHQ0F4hYj1/Lk2n1nyA03TaBEYRSfMv5zVylueMzS6YCKWKaOi/BHawVmX9s/xnDuEN6W0UlT6d6hAd3cyP+7RxCFAVyjlJmA477b/InAKCvP9OP0xzIWL0hVvm3G60IB83NfG+TBKCD1y4frFiCKjvPMxxikYuuE4vKlD9YtP5mAp914Wc6PCe9jIyteQ== x-ms-office365-filtering-correlation-id: b8ee6f0a-b195-4f44-3465-08d4734e273d x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(2017030254075);SRVR:CO2PR0501MB901; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(72170088055959); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(6040375)(601004)(2401047)(8121501046)(5005006)(3002001)(10201501046)(6041248)(20161123558025)(20161123562025)(20161123555025)(20161123564025)(20161123560025)(6072148);SRVR:CO2PR0501MB901;BCL:0;PCL:0;RULEID:;SRVR:CO2PR0501MB901; x-forefront-prvs: 025796F161 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39410400002)(39450400003)(39840400002)(377454003)(24454002)(7696004)(3846002)(102836003)(6116002)(3280700002)(2900100001)(2906002)(229853002)(2950100002)(88552002)(3660700001)(76176999)(5660300001)(54356999)(50986999)(53936002)(77096006)(6436002)(122556002)(25786009)(606005)(236005)(9686003)(99286003)(6506006)(55016002)(6306002)(54896002)(8676002)(81166006)(189998001)(80792005)(53546009)(33656002)(8936002)(66066001)(110136004)(7736002)(7906003)(38730400002)(19627405001)(6246003)(74316002)(86362001)(75432002)(1600100001);DIR:OUT;SFP:1102;SCL:1;SRVR:CO2PR0501MB901;H:CO2PR0501MB903.namprd05.prod.outlook.com;FPR:;SPF:None;MLV:sfv;LANG:en; spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: multipart/alternative; boundary="_000_CO2PR0501MB9039476CCD65145DDC6A9E7B9310CO2PR0501MB903na_" MIME-Version: 1.0 X-OriginatorOrg: uwyo.edu X-MS-Exchange-CrossTenant-originalarrivaltime: 25 Mar 2017 07:11:26.8207 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: f9cdd7ad-825d-4601-8e9c-a325e02d52da X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO2PR0501MB901 --_000_CO2PR0501MB9039476CCD65145DDC6A9E7B9310CO2PR0501MB903na_ Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Steve, It is quite likely that getting your fuel system to behave would not involv= e looking at more than can be seen in the photo of the pumps that you poste= d. Your item 1 would most likely be resolved if pumps of lower flow ratings we= re 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 lo= wer 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 flo= w from the high volume pump, thus causing the rail pressure to be above the= regulator's pressure rating. It seems unlikely, however, that the pressur= e would drop with the engine running since there is so much more fuel circu= lating 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 o= f them. Consider also the system between the tank and the pumps. Trying t= o draw 140 gal/hr with the two pumps through a single -6 line, and also thr= ough a 20 to 40 micron screen if one is installed as required by the pump m= anufacturer, 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 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 I=92ll remove the pumps to confirm the model and do some testing. In old notes I see I thought they were GSL392=92s. The real obvious is as you show in your calcs, the volume of fuel heading b= ack to the tank with both pumps running is huge. With a piddly little 150hp stock unit that probably has quite a small orifi= ce 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 si= multaneously. 2. The difference between the pumps currently. Why does one draw more curre= nt 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 r= egulator seat. But I think I can remember hearing fuel returning to the tan= k when either pump is running. OR B. The other pump is delivering at idle more fuel pressure/flow than the th= e 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 regu= lator pressure. (I cant remember seeing this during engine testing, but I w= asn=92t 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: 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 > 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 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 > 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 > 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 --_000_CO2PR0501MB9039476CCD65145DDC6A9E7B9310CO2PR0501MB903na_ Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

Steve,


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


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 ar= e using and has worked well with those smaller pumps.


Item 2 may be a result of the pump with the higher current draw having m= ore internal friction causing a load on the motor in addition to the load f= rom 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 re= gulator 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 t= wo pumps are combined.


Item A is unlikely to be the case since if the seat in the regulator had= n'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 su= pport 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 th= rottle.


All this discussion is directed toward the pumps or the system downstrea= m of them.  Consider also the system between the tank and the pumps.&n= bsp; 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 in= volve 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 airc= raft <flyrotary@lancaironline.net> on behalf of steve Izett <flyro= tary@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=92ll remove the pumps to confirm the model and do some testing.
In old notes I see I thought they were GSL392=92s.
The real obvious is as you show in your calcs, the volume o= f fuel heading back to the tank with both pumps running is huge.
With a piddly little 150hp stock unit that probably has qui= te a small orifice for bypassing regulation, quite large pressures are goin= g to build up.
I have the two problems though.
1. Flow capacity of the regulator if I want to be able to r= un 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 dr= opped 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/flo= w to break the regulator seat. But I think I can remember hearing fuel retu= rning 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=92t looking fo= r 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<= /a>> wrote:

Steve,

Examining th= e Walbro pump specifications at:
https://wal= brofuelpumps.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 y= our engine could use 20 gal/hr, that would still leave 50 gal/hr returning to the tank.  With two of those pumps runni= ng at 65 psi  
they should be moving 60 gal/hr each with each drawing 10 a= mps.  If your engine was using 20 gal/hr, 100 gal/hr would be returnin= g to the tank.  This would seem to be moving much more fuel than neces= sary.  Depending on where you are measuring the fuel pressure and the details of the fuel flow path, the pressure at t= he 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 a= re using either by identifying them or measuring their flow rates.  GS= L393  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@lancai= ronline.net> on behalf of Charlie England <flyrotary@lancaironline.net>
Sent: F= riday, March 24, 2017 12:24 PM
To: Rot= ary 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 characte= ristics.
Just a pain in the but to get to.
Thanks
Steve



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

Have you tried swapping the position of the pum= ps & 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 alum= inium lines feed from a 28 gallon header tank above to the right.
Fuel then passes through the firewall and race filter befor= e feeding the rail and returning via the pressure regulator (4cyl toyota re= g) 
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 pum= ps 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) und= er higher head pressure
Top pump goes from 9.9A -> 14.8A (5.1A increase) under s= ame 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 power is applied)
I think I modelled the pump layout/manifold after seeing so= meone else=92s and not sure if it causes any problems?
The pumps came from eBay stating that they were genuine Wal= bro and now I=92m wondering.

Cheers

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





<Fuel Pres Pumps.JPG>

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