Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b1) with ESMTP id 3138323 for flyrotary@lancaironline.net; Wed, 31 Mar 2004 07:57:03 -0500 Received: from edward (clt25-78-058.carolina.rr.com [24.25.78.58]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i2VCv0Sn010845 for ; Wed, 31 Mar 2004 07:57:01 -0500 (EST) Message-ID: <002601c4171f$a987a280$2402a8c0@edward> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: One more question (Tracy, see comments inred) Date: Wed, 31 Mar 2004 07:57:02 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0023_01C416F5.C06A3140" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0023_01C416F5.C06A3140 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =20 Good explanation and I agree with everything except the part about RPM = not being used by the EC2. Engine speed is a primary input to the = system, hence the term "speed - density system". =20 Ok, if I understand you correctly, Tracy, then RPM IS a = computational variable in determining fuel injector pulse duration and = not just the "frequency of injection" factor. Is RPM an adjustment for = "Volumetric Efficiency" at different rpms or used for a different = purpose?? Ed 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 engine to be out of phase with what the engine = is doing.=20 At very low throttle, the volume of air in the runner 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 load 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. =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 the runner. These are the factors that made me advise against moving the injectors = out to the far end of the runners. Tracy=20 ------=_NextPart_000_0023_01C416F5.C06A3140 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Good explanation and I agree with everything except the part = about RPM=20 not being used by the EC2. Engine speed is a primary input to = the=20 system, hence the term "speed - density system".

Ok, if I understand you = correctly, Tracy,=20 then RPM IS a computational variable in determining = fuel=20 injector pulse duration and not just the "frequency of injection"=20 factor. Is RPM an adjustment for "Volumetric Efficiency" at = different rpms or used for a different purpose??

Ed

After giving it some more thought, I think the long distance = between=20 injector and port has a large part to play in this problem. It = causes=20 the fuel delivery to the engine to be out of phase with what the = engine is=20 doing.

At very low throttle, the volume of air in the runner can = represent=20 almost all the air that the chamber is going to inhale in one cycle. = Since the=20 injection pulse calculated and injected for that cycle is at the far = end, the=20 engine is not actually going to get that load of fuel until the NEXT=20 cycle. If conditions are changing rapidly (which can definitely = happen=20 at low rpm) the charge for one cycle can be very different than for = the next=20 one.

In addition to this factor, the injected charge is sitting in the = runner=20 waiting for the next cycle and has a chance to condense on the walls = of the=20 runner.

These are the factors that made me advise against moving the = injectors=20 out to the far end of the runners.

Tracy

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