X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail24.syd.optusnet.com.au ([211.29.133.165] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTPS id 950796 for flyrotary@lancaironline.net; Fri, 20 May 2005 04:26:03 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.133.165; envelope-from=lendich@optusnet.com.au Received: from george (d211-29-182-27.dsl.nsw.optusnet.com.au [211.29.182.27]) by mail24.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id j4K8P39M025242 for ; Fri, 20 May 2005 18:25:07 +1000 Message-ID: <002201c55d16$13abb150$1bb61dd3@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: More MAP measurement questions Date: Fri, 20 May 2005 18:29:43 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001F_01C55D69.E42F46E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_001F_01C55D69.E42F46E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageEd, Rusty, Bill, Anyone. Here's another question - having little knowledge in the area, I'm = considering Tracy's ECU and the EM2. What are your appreciations of the products. Is it the EM2 which provides the auto tune capability ? George (down under) Hi George, I'll give it a shot. The Ec2 basically determines how much fuel to = inject using two factors - MAP (Manifold Absolute Pressure) and OAT = which basically tells it how dense the air is that the engine is = ingesting from the manifold. The Ec2 then examines its memory settings = (a different Map - read further)programmed in its memory (which you can = adjust with a mixture knob) for that manifold pressure match. Since the = manifold pressure can vary from apporx 12" Hg to 30"Hg (non-turbo), = there are a series of memory locations generally also referred to as the = MAP (MAP in this case referring to a topological chart) of the fuel = settings. If you plot the fuel mixture settings against RPM and Pressure = it looks like a 2 dim map). So once it matches the manifold pressure = it senses through the manifold pressure sensors with the corresponding = memory location it extracts the injector timing for that MAP and sends = it on to the injectors (with corrections for air temp). The injectors fire once per revolution of the E shaft (which = corresponds to one face of an rotor, therefore, the faster the rpm the = more frequently the injectors fire. But, it basically provides the same = amount of fuel per revolution per specific manifold pressure (which of = course is controlled by the throttle setting and engine rpm) perhaps = adjusted for Ve and OAT. Manifold Absolute Pressure is also one parameter to determine how well = you induction system is working. At sea level the MAP is 29.92" Hg. So = when you open your throttle wide open, you would like to see 29.92" Hg = on the gauge. If you do not and see less than 29.92"Hg (at sea level) = then that implies there is a restriction in your intake and a resulting = pressure loss. Less pressure means less dense air in the manifold which = means less fuel can be burnt which means less power. =20 That is the reason Rusty is concerned about whether the MAP he is = seeing really reflects what his engine is seeing or some fluke of where = the sensing port is in the intake. Generally you would like to have = less that 1/2" of a pressure drop any more than that (if its real) and = you are starting to loose power potential. So if the drop is real then = Rusty probably wants to modify his intake to eliminate it - if its just = a fluke of where he is sensing it - then he does not need to go to the = trouble of designing and fabricating a new intake. =20 That's my take on it. Hope it helps. Ed ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Thursday, May 19, 2005 2:13 AM Subject: [FlyRotary] Re: More MAP measurement questions Al,Rusty and All, Excuse my ignorance here, I have absolutely no knowledge about how = ECU's work. I've heard people say that it reads MAP settings - so what = is a MAP, and if it's different because the pressure is different at = different places in the inlet, how can the computer calculate the inlet = charge and timing. I'm confused! George ( down under) Greetings, I'm working on a new theory about my low MAP reading. The theory = is that this isn't a problem at all, but rather a difference in the way = it's being measured. =20 What's new about this theory? This is what I was telling you a = week or two ago. J I apologize for lack of clarity, causing you to have to re-invent = this theory. Al (Also running TWM TB) The TWM TB has a MAP port about 4 inches past the entrance of the = TB throat. That means I'm measuring the air pressure on the suction = side of the largest restriction in the system (from wide open space, to = 41mm tube). Since there's no significant restriction downstream from = the TB, I would guess that I could measure the MAP at the inlet of the = side housing, and wouldn't find it significantly lower than what I'm = seeing in the TWM TB. In other words, I'm measuring the worst possible = MAP, which is the suction side. =20 From what I understand, the typical (if there is such a thing) = intake has a large TB, feeding into an open plenum, then into the = smaller runners that go to the engine. If I'm not mistaken, virtually = everyone is measuring their MAP in the open plenum, before the air has = to enter the smaller runners to go to the engine. In other words, the = people who are reading 30" are doing it on the pressure side of the = largest restriction. =20 I could babble on about this, but my point is to ask where others = are measuring their MAP (turbo folks need not apply). You'll also have = to give a general description of your intake layout. I already know = that Ed and Tracy are using the "typical" situation. Is anyone = measuring MAP in the runner to the engine? =20 Cheers, Rusty (duty calls...) =20 ------=_NextPart_000_001F_01C55D69.E42F46E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Ed, Rusty, Bill, Anyone.
Here's another question - having little = knowledge=20 in the area, I'm considering Tracy's ECU and the EM2.
What are your appreciations of the=20 products.
Is it the EM2 which provides the = auto tune=20 capability ?
George (down under)
Hi George,
 
I'll give it a shot.  The Ec2 basically = determines=20 how much fuel to inject using two factors - MAP (Manifold Absolute = Pressure)=20 and OAT which basically tells it how dense the air is that the engine = is=20 ingesting from the manifold.  The Ec2 then examines its=20 memory settings (a different Map - read further)programmed =  in its=20 memory (which you can adjust with a mixture knob) for that manifold = pressure=20 match.  Since the manifold pressure can vary from apporx 12" Hg = to 30"Hg=20 (non-turbo), there are a series of memory locations generally also = referred to=20 as the MAP (MAP in this case referring to a topological chart) of the = fuel=20 settings. If you plot the fuel mixture settings against RPM and = Pressure it=20 looks like a 2 dim map).    So once it matches the = manifold=20 pressure it senses through the manifold pressure sensors with the=20 corresponding memory location it extracts the injector timing for that = MAP and=20 sends it on to the injectors (with corrections for air = temp).
 
The injectors fire once per revolution of the = E shaft=20 (which corresponds to one face of an rotor, therefore, the faster the = rpm the=20 more frequently the injectors fire.  But, it basically provides = the same=20 amount of fuel per revolution per specific manifold pressure (which of = course=20 is controlled by the throttle setting and engine rpm) perhaps adjusted = for Ve=20 and OAT.
 
Manifold Absolute Pressure is also one = parameter to=20 determine how well you induction system is working.  At sea level = the MAP=20 is 29.92" Hg.  So when you open your throttle wide open, you = would like=20 to see 29.92" Hg on the gauge.  If you do not and see less than = 29.92"Hg=20 (at sea level) then that implies there is a restriction in your intake = and a=20 resulting pressure loss.  Less pressure means less dense air in = the=20 manifold which means less fuel can be burnt which means less=20 power.  
 
That is the reason Rusty is concerned about = whether the=20 MAP he is seeing really reflects what his engine is seeing or some = fluke of=20 where the sensing port is in the intake.  Generally you would = like to=20 have less that 1/2" of a pressure drop any more than that (if its = real) and=20 you are starting to loose power potential.  So if the drop is = real then=20 Rusty probably wants to modify his intake to eliminate it - if its = just a=20 fluke of where he is sensing it - then he does not need to go to the = trouble=20 of designing and fabricating a new intake. 
 
That's my take on it.  Hope it = helps.
 
Ed
----- Original Message -----
From:=20 George Lendich
To: Rotary motors in = aircraft=20
Sent: Thursday, May 19, 2005 = 2:13=20 AM
Subject: [FlyRotary] Re: More = MAP=20 measurement questions

Al,Rusty and All,
Excuse my ignorance here, I have = absolutely no=20 knowledge about how ECU's work. I've heard people say that it reads = MAP=20 settings - so what is a MAP, and if it's different because the = pressure is=20 different at different places in the inlet, how can the computer = calculate=20 the inlet charge and timing.
I'm confused!
George ( down under)

 

Greetings,

 

I'm = working on a=20 new theory about my low MAP reading.  The theory is that this = isn't a=20 problem at all, but rather a difference in the way it's being=20 measured. 

 

What=92s new=20 about this theory?  This is what I was telling you a week or = two ago.=20 J

I = apologize for=20 lack of clarity, causing you to have to re-invent this=20 theory.

 

Al = (Also=20 running TWM TB)

 

The = TWM TB has a=20 MAP port about 4 inches past the entrance of the TB = throat.  =20 That means I'm measuring the air pressure on the suction side of = the=20 largest restriction in the system (from wide open space, to 41mm=20 tube).   Since there's no significant restriction = downstream=20 from the TB, I would guess that I could measure the MAP at = the=20 inlet of the side housing, and wouldn't find it significantly = lower=20 than what I'm seeing in the TWM TB.  In other words, I'm = measuring the worst possible MAP, which is the suction = side. =20   

 

From = what I=20 understand, the typical (if there is such a thing) intake has a = large TB,=20 feeding into an open plenum, then into the smaller runners = that go to=20 the engine.  If I'm not mistaken, virtually = everyone is=20 measuring their MAP in the open plenum, before the air has to = enter the=20 smaller runners to go to the engine.  In other=20 words, the people who are reading 30" are doing it on the = pressure=20 side of the largest = restriction.  

 

I = could babble on=20 about this, but my point is to ask where others are measuring = their MAP=20 (turbo folks need not apply).  You'll also have to give a = general=20 description of your intake layout.   I already know that = Ed and=20 Tracy are using the "typical" situation.  Is anyone measuring = MAP in=20 the runner to the engine?  

 

Cheers,

Rusty = (duty=20 calls...)

 =20 =

------=_NextPart_000_001F_01C55D69.E42F46E0--