Return-Path: Sender: (Marvin Kaye) To: lml Date: Wed, 20 Aug 2003 14:38:36 -0400 Message-ID: X-Original-Return-Path: Received: from luke.cpl.net ([216.117.199.213] verified) by logan.com (CommuniGate Pro SMTP 4.1.1) with ESMTP-TLS id 2535057 for lml@lancaironline.net; Wed, 20 Aug 2003 13:11:46 -0400 Received: from [192.168.0.21] ([216.117.196.106]) by luke.cpl.net (8.11.3/8.11.3) with ESMTP id h7KHBil69749 for ; Wed, 20 Aug 2003 10:11:44 -0700 (PDT) User-Agent: Microsoft-Entourage/10.1.4.030702.0 X-Original-Date: Wed, 20 Aug 2003 10:11:43 -0700 Subject: Re: [LML] Re: Percent horsepower calculations? From: Hal Woodruff X-Original-To: Lancair Mailing List X-Original-Message-ID: In-Reply-To: Mime-version: 1.0 Reply-To: woodruff@swefco.com Content-type: multipart/alternative; boundary="B_3144219104_3675224" > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3144219104_3675224 Content-type: text/plain; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Hi Ron, The 13.75 factor is the right number for most turbo installations. George made a special case for the TSIO550 saying that he would use the 14.7 number. It has something to do with the timing which is 24=B0 BTDC on that engine. The factor for normally aspirated LOP is 15.0. Also, after reviewing my notes from the APS, those running ROP (normally aspirated) should use 29" as the divisor for the manifold pressure part of the equation I cited. It'll come out a little closer to the factory percentages. % power =3D ((MP/29) * (RPM/2700)) * 100 For normally aspirated engines the following works also. For each inch of manifold pressure decrease from max (29") reduce the power by 3.5%; and for each 100 RPMs less than max (2700) reduce the power by 2.5%. For example: running at 24" MP and 2400 RPM (100 - (29"-24")*3.5 - ((2700-2400)/100)*2.5) =3D 75% power This was promoted as something "you can do in your head". Not my head - that's why I printed out the spreadsheet. Hal --B_3144219104_3675224 Content-type: text/html; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Re: [LML] Re: Percent horsepower calculations? Hi Ron,

The 13.75 factor is the right number for most turbo installations.  Ge= orge made a special case for the TSIO550 saying that he would use the 14.7 n= umber.  It has something to do with the timing which is 24° BTDC on= that engine.  The factor for normally aspirated LOP is 15.0.

Also, after reviewing my notes from the APS, those running ROP (normally as= pirated) should use 29" as the divisor for the manifold pressure part o= f the equation I cited.  It'll come out a little closer to the factory = percentages.  % power =3D ((MP/29) * (RPM/2700)) * 100

For normally aspirated engines the following works also.  For each inc= h of manifold pressure decrease from max (29") reduce the power by 3.5%= ; and for each 100 RPMs less than max (2700) reduce the power by 2.5%.

For example:  running at 24" MP and 2400 RPM
(100 - (29"-24")*3.5 - ((2700-2400)/100)*2.5) =3D 75% power

This was promoted as something "you can do in your head".  <= B>Not my head - that's why I printed out the spreadsheet.

Hal
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