Return-Path: Received: from fed1mtao05.cox.net ([68.6.19.126] verified) by logan.com (CommuniGate Pro SMTP 4.1.3) with ESMTP id 2568369 for flyrotary@lancaironline.net; Fri, 05 Sep 2003 01:11:18 -0400 Received: from Leonards ([68.111.228.182]) by fed1mtao05.cox.net (InterMail vM.5.01.06.04 201-253-122-130-104-20030726) with ESMTP id <20030905051114.RVPS1408.fed1mtao05.cox.net@Leonards> for ; Fri, 5 Sep 2003 01:11:14 -0400 From: "David Leonard" To: "'Rotary motors in aircraft'" Subject: Rusty's Power seems about right Date: Thu, 4 Sep 2003 22:11:17 -0700 Message-ID: <000001c3736c$22c4f060$b6e46f44@Leonards> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C37331.76661860" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.3416 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C37331.76661860 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Rusty, I have been thinking about your apparently less power than you expected for a given manifold pressure (ie. 30 in Hg) and thought of a few points you may not have considered. You were disappointed that power seemed to be anemic at 30 in. compared to what you would expect an n/a engine to produce at WOT. However, with the turbo, several things change. First is back pressure. That turbo is creating significant back pressure that an NA engine doesn't see. This mean that for a given intake pressure you are producing less net torque and therefore a lower h.p., which leads to a lower RPM - and even less h.p. You should make your power references to n.a engines based on the RPM you are producing and not on the MAP. You may have to run a higher MAP to get the same RPM as a n/a engine, but that is what the turbo is all about, the availability of a higher MAP. Next is temperature. Especially without an intercooler, your 30in. air is considerably less dense than 30in n/a air resulting in lower power. Again, compensate by running a higher MAP until your RPM is where you want it to be. You will ultimately have more available power, but nothing is for free. David Leonard The Rotary Roster: http://members.aol.com/_ht_a/rotaryroster/index.html ------=_NextPart_000_0001_01C37331.76661860 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

Rusty,

 

I have been thinking about your = apparently less power than you expected for a given manifold pressure (ie. 30 in = Hg) and thought of a few points you may not have considered.   You = were disappointed that power seemed to be anemic at 30 in. compared to what you would = expect an n/a engine to produce at WOT.  However, with the turbo, several things change. 

 

First is back pressure.  That = turbo is creating significant back pressure that an NA engine doesn’t see.  This mean that for a given intake pressure you are producing = less net torque and therefore a lower h.p., which leads to a lower RPM = – and even less h.p.  You should make your power references to n.a engines = based on the RPM you are producing and not on the MAP.  You may have to run = a higher MAP to get the same RPM as a n/a engine, but that is what the = turbo is all about, the availability of a higher MAP.

 

Next is temperature.  = Especially without an intercooler, your 30in. air is considerably less dense than = 30in n/a air resulting in lower power.  Again, compensate by running a = higher MAP until your RPM is where you want it to be.  You will ultimately = have more available power, but nothing is for free.

 

David Leonard

The Rotary = Roster:

http://memb= ers.aol.com/_ht_a/rotaryroster/index.html

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