X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 15 Feb 2010 07:59:31 -0500 Message-ID: X-Original-Return-Path: Received: from web57501.mail.re1.yahoo.com ([66.196.100.68] verified) by logan.com (CommuniGate Pro SMTP 5.3.2) with SMTP id 4125370 for lml@lancaironline.net; Mon, 15 Feb 2010 07:47:04 -0500 Received-SPF: none receiver=logan.com; client-ip=66.196.100.68; envelope-from=casey.gary@yahoo.com Received: (qmail 78289 invoked by uid 60001); 15 Feb 2010 12:46:28 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=vIhJaqkFFZAmGoPn9CuOZZu2wU8iAnpHhzHkMhFqwh0WevuvmjeTQdZ6UqQ6iK7jMVsS34uVkkmKmhyO5+5zwDYmnTT6bG4gqMTkhyjuz6KGq9SCzLwk8d1QfAqRh1BfVRBhcC4qrRD3ujc6WnOwORSE1iKp8XjI26CdFuUvNVg=; X-Original-Message-ID: <650046.77966.qm@web57501.mail.re1.yahoo.com> X-YMail-OSG: WAw97JMVM1nzqcjjqUnLWze2TRnTUQTq6EGbRO_a2MJqWWn0Qjfqqi2IjSi29vz1xfIVvGyWwQu9W1XsmDToES9t9yZaD7Gp0Rmiy.v706TZNX9K9G8IAT2ycl6sF4QPYH9j70towT6bjQwTxowFZ_1AFI3LZi1XTvNsoNfVlXiV5jnemng4aFlfJslkpEebFJJRA51njdtHQIgELGySHjAyMv2sa.wcl75Xp5FnNMLQuftl_CKLaYRvi05zfR_hd8arkcFhb6_OfenMPLtVt3RHrBwmHzm89trUxa_nOpDkoXfGo2xjJEOQgzGAtL5KlpgLPWT6cq42ReAWjQdAOww- Received: from [97.122.153.67] by web57501.mail.re1.yahoo.com via HTTP; Mon, 15 Feb 2010 04:46:28 PST X-Mailer: YahooMailRC/300.3 YahooMailWebService/0.8.100.260964 References: X-Original-Date: Mon, 15 Feb 2010 04:46:28 -0800 (PST) From: Gary Casey Subject: Re: IO-550N MP/RPM vs % HP table? X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1317816783-1266237988=:77966" --0-1317816783-1266237988=:77966 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Someone might have numbers based on actual data, but in lieu of that, using= a reasonable approximation might be reasonable(sic). A first approximatio= n is that power is proportional to both engine speed (RPM) and manifold pre= ssure. Compared to the rated hp (HPr) the actual hp would be: HPa =3D HPr= * RPMa/RPMr * MAPa/MAPr. But, as someone famous once said, "to tell the t= ruth that's not quite true." Engine friction hp subtracts from the indicat= ed power (the power developed within the cylinders). When close to full po= wer ( I assume you only care when running something over 50% power) an impr= ovement over the above calculation might be to add a 10% additional correct= ion. The correction works in the opposite direction for rpm as it does for= MAP. For a 10% drop in rpm from rated, drop the power by 9%. For a 10% d= rop in MAP lower the power by 11%. I could come up with an equation, but i= t's early and my brain cells are kind of slow :-) For power settings below 50 or 60% this approximation rapidly falls apart, but do you care to= know the power below that? I doubt it. And a bigger effect is due to air= /fuel mixture while the above approximation is only good for a fixed mixtur= e. Takeoff power (full rich) probably drops the power about 2% from LBT (L= eanest mixture for Best Torque) and running LOP will drop power by 5 to 15%= . So the above calculation might work ok for rich mixtures, but isn't very= good when running LOP. As George would say, LOP operation will produce po= wer pretty much proportional to fuel flow and is independent of MAP and RPM= (he has a number for this that I forgot).=0AGary=0A=0A=0A=0A_______________= _________________=0AIO-550N MP/RPM vs % HP table=E2=80=8F=0AFebruary 14, 20= 10 1:23:46 PM MST=0AFrom:=0A"Curt Cannon" =0ATo:= =0A"" =0A=0A=0A________________________________=0AI = need to get this info to program my engine monitor. Anybody have it handy?= =0A=0A=0A --0-1317816783-1266237988=:77966 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Someone might have numbers based on actual data, b= ut in lieu of that, using a reasonable approximation might be reasonable(si= c).  A first approximation is that power is proportional to both engin= e speed (RPM) and manifold pressure.  Compared to the rated hp (HPr) t= he actual hp would be:  HPa =3D HPr * RPMa/RPMr * MAPa/MAPr.  But= , as someone famous once said, "to tell the truth that's not quite true." &= nbsp;Engine friction hp subtracts from the indicated power (the power devel= oped within the cylinders).  When close to full power ( I assume you o= nly care when running something over 50% power) an improvement over the abo= ve calculation might be to add a 10% additional correction.  The corre= ction works in the opposite direction for rpm as it does for MAP.  For a 10% drop in rpm from rated, drop the power by 9%.  For a = 10% drop in MAP lower the power by 11%.  I could come up with an equat= ion, but it's early and my brain cells are kind of slow :-)  For power= settings below 50 or 60% this approximation rapidly falls apart, but do yo= u care to know the power below that?  I doubt it.  And a bigger e= ffect is due to air/fuel mixture while the above approximation is only good= for a fixed mixture.  Takeoff power (full rich) probably drops the po= wer about 2% from LBT (Leanest mixture for Best Torque) and running LOP wil= l drop power by 5 to 15%.  So the above calculation might work ok for = rich mixtures, but isn't very good when running LOP.  As George would = say, LOP operation will produce power pretty much proportional to fuel flow= and is independent of MAP and RPM(he has a number for this that I forgot).=
Gary

IO-550N MP/RPM vs % HP table=E2=80=8F
February 14, 2010 1:2= 3:46 PM MST
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Fr= om:
"Curt Cannon" <curtsuecannon@hotmail.com><= /div>
To:
"" <lml@lancaironline.net>
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I need to get this info to program my engine moni= tor.  Anybody have it handy?
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