Return-Path: Received: from [65.54.168.124] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.2b1) with ESMTP id 3137450 for flyrotary@lancaironline.net; Tue, 30 Mar 2004 19:36:27 -0500 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Tue, 30 Mar 2004 16:36:23 -0800 Received: from 67.25.179.186 by bay3-dav20.bay3.hotmail.com with DAV; Wed, 31 Mar 2004 00:36:22 +0000 X-Originating-IP: [67.25.179.186] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: No rev-2 flying yet (Tracy, see comments inred) Date: Tue, 30 Mar 2004 19:36:16 -0500 MIME-Version: 1.0 X-Mailer: MSN Explorer 7.02.0011.2700 Content-Type: multipart/alternative; boundary="----=_NextPart_001_0004_01C4168E.44B66DF0" Message-ID: X-OriginalArrivalTime: 31 Mar 2004 00:36:23.0222 (UTC) FILETIME=[316CBD60:01C416B8] ------=_NextPart_001_0004_01C4168E.44B66DF0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Good explanation and I agree with everything except the part about RPM no= t being used by the EC2. Engine speed is a primary input to the system, = hence the term "speed - density system". =20 After giving it some more thought, I think the long distance between inje= ctor and port has a large part to play in this problem. It causes the fu= el delivery to the engine to be out of phase with what the engine is doin= g. =20 At very low throttle, the volume of air in the runner can represent almo= st all the air that the chamber is going to inhale in one cycle. Since th= e injection pulse calculated and injected for that cycle is at the far en= d, the engine is not actually going to get that load of fuel until the NE= XT cycle. If conditions are changing rapidly (which can definitely happe= n at low rpm) the charge for one cycle can be very different than for the= next one. =20 In addition to this factor, the injected charge is sitting in the runner = waiting for the next cycle and has a chance to condense on the walls of t= he runner. These are the factors that made me advise against moving the injectors ou= t to the far end of the runners. Tracy =20 ----- Original Message ----- From: Russell Duffy Sent: Tuesday, March 30, 2004 12:31 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: No rev-2 flying yet (Tracy, see comments inred) My guess is that it appears that when closing the throttle very rapidly,= you probably end up with an overly rich intake manifold air/fuel mixtur= e. This may occur because in one fraction of a second you are opearting= at WOT (lots of fuel flow) and the next down to idle. So the rpm drops= down in to the LOW, LOW range due to the rapid decrease in manifold pres= sure caused by the rapid throttle closure and still rapidly pumping rotor= s. So its down in the low rpm range with a rich mixture and then since t= he rpm is so low, the manifold pressure may well creeep back up to the 1= 6-17" Hg range simple because there is not enough rpm to keep the manifo= ld pressure lower. So now the system is seeing higher manifold pressur= e. Since the system only really uses the manifold pressure (and not rpm)= in its calculation, the higher manifold pressure convinces itself that = you have opened the throttle a bit (while you actually have not) and so i= t dumps in a bit more fuel. This keeps the mixture overly rich as there i= s really not as much air coming into the system. Once you crack the thro= ttle a bit, more air flow leans out the mixture, rpm increases, manifold = pressure actually decrease back to 14-15" Hg and the system stabilizes. =20 GREAT explanation!!! That's got to be exactly what's happening. Thanks, Rusty (now I can ignore that "problem") =20 ------=_NextPart_001_0004_01C4168E.44B66DF0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Good explanation and I agree with everyth= ing except the part about RPM not being used by the EC2. Engine spe= ed is a primary input to the system, hence the term "speed - density syst= em".

After giving it some more = thought, I think the long distance between injector and port has a large = part to play in this problem. It causes the fuel delivery to the en= gine to be out of phase with what the engine is doing.

&= nbsp;

At very low throttle, the volume of air in the run= ner can represent almost all the air that the chamber is going to inhale = in one cycle. Since the injection pulse calculated and injected for that = cycle is at the far end, the engine is not actually going to get that loa= d of fuel until the NEXT cycle. If conditions are changing rapidly = (which can definitely happen at low rpm) the charge for one cycle can be = very different than for the next one.

In addition to this factor, the injected charge is sitting in the runner= waiting for the next cycle and has a chance to condense on the walls of = the runner.

These are the factors that made = me advise against moving the injectors out to the far end of the runners.=

Tracy

----- Original Message -----

From: Russell Duffy

Sent: Tuesday, March 30, 2004 12:31 PM
To: Rotary motors in aircraft<= /DIV>
Subject: [FlyRotary] Re: No = rev-2 flying yet (Tracy, see comments inred)