Return-Path: Received: from [65.54.169.55] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.2b1) with ESMTP id 3139719 for flyrotary@lancaironline.net; Wed, 31 Mar 2004 23:50:41 -0500 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Wed, 31 Mar 2004 20:50:40 -0800 Received: from 67.25.179.46 by bay3-dav25.adinternal.hotmail.com with DAV; Thu, 01 Apr 2004 04:50:40 +0000 X-Originating-IP: [67.25.179.46] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: One more question : EC2 operation Date: Wed, 31 Mar 2004 23:50:35 -0500 MIME-Version: 1.0 X-Mailer: MSN Explorer 7.02.0011.2700 Content-Type: multipart/alternative; boundary="----=_NextPart_001_0002_01C4177A.F5EB3D20" Message-ID: X-OriginalArrivalTime: 01 Apr 2004 04:50:40.0806 (UTC) FILETIME=[E2110C60:01C417A4] ------=_NextPart_001_0002_01C4177A.F5EB3D20 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 Ok, if I understand you correctly, Tracy, then RPM IS a computational v= ariable in determining fuel injector pulse duration and not just the "fre= quency of injection" factor. Is RPM an adjustment for "Volumetric Effici= ency" at different rpms or used for a different purpose?? Ed Guess a little more detail is needed to explain this. The EC2 re-compute= s the injection requirements in real time. Just before the intake cycle = starts, it computes the required fuel for this individual intake cycle. = You can't get any more closely tied to RPM than this. The volumetric efficiency is very much affected by the design of the inta= ke system. Since there are no two alike out there (at this time), it is = not possible to take VE into consideration as a function of RPM. Detroit= has it much easier in this respect because they can control every detail= of the engine. Tracy Ok, one more time for us slow folks. I understand that the EC2 calculati= ons some "adjustment" to the fuel requirement for each intake cycle. Sinc= e the intake cycle is certainly tied to rpm in so far that the rpm determ= ines the number of intake events per unit time. I think I follow that e= ach intake cycle can be different as far as fuel requirement. I had as= sumed that the fuel injection adjusment is primarily based on the manifol= d pressure it senses. In otherwords, if the Ec2 senses 17" Hg manifold p= ressure at a specific intake manfiold air temp it calculates X millesecon= ds of injection time. I had assumed that this amount of injection time w= ould be the same whether 17" at 3000 rpm or 17" at 5000 rpm but that sinc= e the injector fires more times/sec at 5000 rpm than 3000 rpm there would= be more fuel injected. In otherwords, I had assumed that since the EC2= does its calculation for each cycle, it didn't know(orcare) whether the = cydle was happening at 3000 rpm or 5000 rpm only what the manifold pressu= re was at each rpm. Since my assumption is apparently incorrect, then over a beer, you need t= o explain it to me one more time how the RPM is a factor in the computati= on of fuel injection time. I strongly suspected that Ve wasn't really a factor for the reasons you s= tated, too bad {:>) Ed Anderson I think semantics are confusing both of us (or me at least : ). If we l= ook at it in terms of a single intake cycle, rpm does not figure into the= equation. If you look at it in terms of CC per minute or gallons per hou= r, it does. However, in the latest version of the software (which Rust= y has), rpm does have an effect in that a different MAP table is used for= high and low RPM ranges. =20 Tracy (who would never accuse Ed of being slow ! ) ------=_NextPart_001_0002_01C4177A.F5EB3D20 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
 
Good explanation and I agree with everything exce= pt 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".&nbs= p; 
 
Ok, if I understand you correctly, Tracy, &nbs= p;then RPM IS a  computational variable in determining fuel inj= ector pulse duration and not just the "frequency of injection" factor.&nb= sp; Is RPM an adjustment for "Volumetric Efficiency" at different rp= ms or used for a different purpose??
 
Ed
 
Gues= s a little more detail is needed to explain this.  The EC2 re-comput= es the injection requirements in real time.  Just before the in= take cycle starts, it computes the required fuel for this individual= intake cycle.  You can't get any more closely tied to RPM than this=
 
The volumetric efficiency is very muc= h affected by the design of the intake system.  Since ther= e are no two alike out there (at this time), it is not possible to t= ake VE into consideration as a function of RPM.  Detroit has it much= easier in this respect because they can control every detail of the engi= ne.
 
Tracy
 
Ok, one more time= for us slow folks.  I understand that the EC2 calculations some "ad= justment" to the fuel requirement for each intake cycle. Since the intake= cycle is certainly tied to rpm in so far that the rpm determines the num= ber of intake events per unit time.  I think I follow  that eac= h intake cycle can be different as far as fuel requirement.   I= had  assumed that the fuel injection adjusment is primarily based o= n the manifold pressure it senses.  In otherwords, if the Ec2 senses= 17" Hg manifold pressure at a specific intake manfiold air temp it = calculates X milleseconds of injection time.  I had assumed that thi= s amount of injection time would be the same whether 17" at 300= 0 rpm or 17" at 5000 rpm but that since the injector fires more times/sec= at 5000 rpm than 3000 rpm there would be more fuel injected.   = ;In otherwords, I had assumed that since the EC2 does its calculation for= each cycle, it didn't know(orcare) whether the cydle was happening at 30= 00 rpm or 5000 rpm only what the manifold pressure was at each rpm.
 
= Since my assumption is apparently inco= rrect, then over a beer, you need to explain it to me one more time how t= he RPM is a factor in the computation of fuel injection time.
 
I strongly suspected that Ve wasn't really a= factor for the reasons you stated, too bad {:>)
&nb= sp;
Ed Anderson
 
I think semantics are confusing both of us (= or me at least  : ).  If we look at it in terms of a single int= ake cycle, rpm does not figure into the equation. If you look at it in te= rms of CC per minute or gallons per hour, it does.   Howev= er,  in the latest version of the software (which Rusty has), rpm do= es have an effect in that a different MAP table is used for high and low = RPM ranges. 
 
Tracy  (who would never a= ccuse Ed of being slow !  )
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