X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 25 May 2012 13:17:40 -0400 Message-ID: X-Original-Return-Path: Received: from db3outboundpool.messaging.microsoft.com ([213.199.154.139] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTPS id 5560047 for lml@lancaironline.net; Fri, 25 May 2012 12:09:38 -0400 Received-SPF: pass receiver=logan.com; client-ip=213.199.154.139; envelope-from=rpastusek@htii.com Received: from mail16-db3-R.bigfish.com (10.3.81.254) by DB3EHSOBE004.bigfish.com (10.3.84.24) with Microsoft SMTP Server id 14.1.225.23; Fri, 25 May 2012 16:08:49 +0000 Received: from mail16-db3 (localhost [127.0.0.1]) by mail16-db3-R.bigfish.com (Postfix) with ESMTP id C85951200E7 for ; Fri, 25 May 2012 16:08:50 +0000 (UTC) X-Forefront-Antispam-Report: CIP:157.56.245.5;KIP:(null);UIP:(null);IPV:NLI;H:CH1PRD0710HT001.namprd07.prod.outlook.com;RD:none;EFVD:NLI X-SpamScore: -8 X-BigFish: PS-8(zzc85fh328cM98dKzz1202hzz8275bh8275dhz31h2a8h668h839hd25hf0ah) Received-SPF: softfail (mail16-db3: transitioning domain of htii.com does not designate 157.56.245.5 as permitted sender) client-ip=157.56.245.5; envelope-from=rpastusek@htii.com; helo=CH1PRD0710HT001.namprd07.prod.outlook.com ;.outlook.com ; Received: from mail16-db3 (localhost.localdomain [127.0.0.1]) by mail16-db3 (MessageSwitch) id 1337962127652345_21288; Fri, 25 May 2012 16:08:47 +0000 (UTC) Received: from DB3EHSMHS006.bigfish.com (unknown [10.3.81.247]) by mail16-db3.bigfish.com (Postfix) with ESMTP id 9DD0C260048 for ; Fri, 25 May 2012 16:08:47 +0000 (UTC) Received: from CH1PRD0710HT001.namprd07.prod.outlook.com (157.56.245.5) by DB3EHSMHS006.bigfish.com (10.3.87.106) with Microsoft SMTP Server (TLS) id 14.1.225.23; Fri, 25 May 2012 16:08:45 +0000 Received: from CH1PRD0710MB367.namprd07.prod.outlook.com ([169.254.11.36]) by CH1PRD0710HT001.namprd07.prod.outlook.com ([10.255.152.36]) with mapi id 14.16.0164.004; Fri, 25 May 2012 16:08:56 +0000 From: Robert R Pastusek X-Original-To: Lancair Mailing List Subject: RE: [LML] boost pump for engine cooling 4P Thread-Topic: [LML] boost pump for engine cooling 4P Thread-Index: AQHNOn6eMWq8EHXLZEWmw033a7CTcpbap/lA X-Original-Date: Fri, 25 May 2012 16:08:56 +0000 X-Original-Message-ID: <41361035E6613244A377D5AC3BF5EFDD164B7E0B@CH1PRD0710MB367.namprd07.prod.outlook.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [72.66.86.7] Content-Type: multipart/alternative; boundary="_000_41361035E6613244A377D5AC3BF5EFDD164B7E0BCH1PRD0710MB367_" MIME-Version: 1.0 X-Original-Return-Path: rpastusek@htii.com X-OriginatorOrg: htii.com --_000_41361035E6613244A377D5AC3BF5EFDD164B7E0BCH1PRD0710MB367_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Ralf wrote: Dear subscribers, A while back I reported a warmer cylinder 4 during climb at 32 MAP and 2500= rpm. Lynn recommended I could test high boost during climb and see if it m= akes a difference. In the mean time I cranked up my fuel pump by approx. 1 GPH. At take-off I = see now 42.5 GPH at 38.4 MAP 2680 rpm (on a TSIO550 B which is rated for 38= MAP at 41...43GPH according to my manual). In climb under full rpm/MAP engine stays very nice and cool. Climb 2500 rpm with 32MAP: all EGTs show the same, after increasing the fue= l flow all CHTs stay generally a bit cooler but CHT 4 is still the one that= runs a little warmer. During climb when CHT4 approached 380 I turned the h= igh boost on - the CHT went down by approx. 10 degrees back into the 360's.= During the climb to 18000 I had the boost pump on 3 times for may be 2 min= each time. The Fuel flow increased from 30.5 to 33 GPH. I climbed with +-1= 70 kts at 1000 fpm. This is new: usually I was never able to get the CHT d= own in climb unless I decreased the climb rate. Question: is it a reasonable practice to use the high boost for engine cool= ing? How long can it run in high boost without getting damaged? Craig reported earlier that he had his fuel pump modified to feed more fuel= under partial power - this sounds complicated and expensive and if I don't= have to I would rather not go there. Thanks for you input Ralf, You are still at the lower level of recommended WOT fuel flow for the big C= ontinental. I have increased my WOT fuel flow to 44 GPH and the engine runs= very cool all the way up. BTW, cylinder head temps of 380 are not worrisom= e; start being concerned/taking action at 400+. Still, keeping the engine c= ool lengthens its life. It's surprising how much cooling just a little extra fuel provides...and th= at's what you are seeing. The boost pump used on the IV-P is rated for cont= inuous operation at low or high boost, but again, it will wear out sooner i= f used a lot...and it's quite expensive. Better to open the fuel flow a bit= more and use the mixture control to moderate it...with one exception/note:= It is possible to feed too much fuel to the engine, which will cause it to= choke/stall (as opposed to flooding-a ground operation issue). You want to= be sure the engine will take full throttle on takeoff without choking/load= ing up. With that caveat, the main problems with feeding it too much fuel a= re fouling the plugs over time, and the cost of extra fuel used. For my mon= ey, the extra gas is cheap insurance for the engine during climb; you can e= conomize when you get the power back in cruise. Hope this helps. Bob --_000_41361035E6613244A377D5AC3BF5EFDD164B7E0BCH1PRD0710MB367_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Ralf wrote:

 

Dear subscribers,

 

A while back I reported a warmer cylinder 4 during c= limb at 32 MAP and 2500 rpm. Lynn recommended I could test high boost durin= g climb and see if it makes a difference.

 

In the mean time I cranked up my fuel pump by approx= . 1 GPH. At take-off I see now 42.5 GPH at 38.4 MAP 2680 rpm (on a TSIO550 = B which is rated for 38 MAP at 41…43GPH according to my manual).

 

In climb under full rpm/MAP engine stays very nice a= nd cool.

 

Climb 2500 rpm with 32MAP: all EGTs show the same, a= fter increasing the fuel flow all CHTs stay generally a bit cooler but CHT = 4 is still the one that runs a little warmer. During climb when CHT4 approa= ched 380 I turned the high boost on – the CHT went down by approx. 10 degrees back into the 360’s.= During the climb to 18000 I had the boost pump on 3 times for may be 2 min= each time. The Fuel flow increased from 30.5 to 33 GPH. I climbed with = 3;-170 kts at 1000 fpm.  This is new: usually I was never able to get the CHT down in climb unless I decreased the climb r= ate.

 

Question: is it a reasonable practice to use the hig= h boost for engine cooling? How long can it run in high boost without getti= ng damaged?

 

Craig reported earlier that he had his fuel pump mod= ified to feed more fuel under partial power – this sounds complicated= and expensive and if I don’t have to I would rather not go there.

 

Thanks for you input<= /p>

 

 <= /p>

 

Ralf,
You are still at the lower level of recommended WOT fuel flow for the big C= ontinental. I have increased my WOT fuel flow to 44 GPH and the engine runs= very cool all the way up. BTW, cylinder head temps of 380 are not worrisom= e; start being concerned/taking action at 400+. Still, keeping the engine cool lengthens its life.

 

It’s surprising how much cooling just a little extra fuel= provides…and that’s what you are seeing. The boost pump used on the IV-P is rated for continuous operation at low or high boo= st, but again, it will wear out sooner if used a lot…and it’s q= uite expensive. Better to open the fuel flow a bit more and use the mixture= control to moderate it…with one exception/note: It is possible to feed too much fuel to the engine, which will cause it to= choke/stall (as opposed to flooding—a ground operation issue). You w= ant to be sure the engine will take full throttle on takeoff without chokin= g/loading up. With that caveat, the main problems with feeding it too much fuel are fouling the plugs over time, an= d the cost of extra fuel used. For my money, the extra gas is cheap insuran= ce for the engine during climb; you can economize when you get the power ba= ck in cruise.


Hope this helps.


Bob

 

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