X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail13.syd.optusnet.com.au ([211.29.132.194] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTPS id 2574140 for flyrotary@lancaironline.net; Mon, 10 Dec 2007 03:06:14 -0500 Received-SPF: pass receiver=logan.com; client-ip=211.29.132.194; envelope-from=lendich@optusnet.com.au Received: from george (d58-109-29-92.dsl.nsw.optusnet.com.au [58.109.29.92]) by mail13.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id lBA85QID018181 for ; Mon, 10 Dec 2007 19:05:28 +1100 Message-ID: <002c01c83b03$6f289390$5c1d6d3a@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Pport timing Date: Mon, 10 Dec 2007 18:05:29 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0029_01C83B57.3FDCAF00" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Antivirus: avast! (VPS 0657-0, 12/12/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_0029_01C83B57.3FDCAF00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Lynn, I'm closer to 60 than 59 so I can relate to that memory thing. That clarifies the timing for me matey - 70 degrees it is then. I notice = that everyone else has followed that trend, moreso just following where = as I have to understand why. I appreciate your clarification on the = subject.=20 Mind you I wouldn't have understand at all, unless I had set-up the = timing wheel, as you originally suggested. Mind you it's a good point to clarify. Thanks! George (down under) BTW have a look at this Aussie Dyno test - you will recognize the Aussie = voices in the background http://youtube.com/watch?v=3DuO1782B6RZw Thanks Lynn, It goes without saying that I always appreciate your contribution. I = may have to refer back to what you were saying to clarify some points. I now understand the closing event has the most effect on the mid = range power we need in Aviation (why is that? and why is your BP closing = of 80 degrees flowing very little - there seems to be plenty of suction = still going on?)=20 The intake closing event is shown as ABDC. After Bottom Dead Center, = in the case of the intake cycle is in the top of the rotor housing. (a = bit confusing) and since BDC for both intake and exhaust cycles is the = largest volume attainable, that closing point is after the volume is = already decreasing. So some of the mixture is being forced back into the = intake manifold. Early closing means more mixture is trapped in the = closing chamber to be used no matter what the state of tune. So at lower and medium speeds where = inertial charging is low to nonexistant, the engine still developes some = amount of power. The later the closing point, the more accurate the tune = must be to support the same performance down low, as only high inertia = can overcome the mixture being pushed out from the closing chamber.=20 So an early closing point captures more mixture, at lower speeds, and = low and medium power is improved. Same as advancing the cam in a piston = engine. Even though it screws up the other three timing functions, the = early closing intake valve makes so much difference it is worth the work = to do it. In a minor way this affects the effective compression ratio as = well. More degrees of closed chamber means higher compression. This = becomes painfully obvious when measuring compression at cranking speeds. = My Fiats had 245 pounds of compression cranking. Run the engine 10 = seconds and shut it off because the NOX would fry you eyes. I could = retard the intake cam 5 degrees and loose 10 pounds. and that closing event should not exceed 70 degrees ABDC. This is = probably something=20 you told me previously and I hadn't remembered ( or understood = properly). However the Mazda Factory PP is 75 degree IC, perhaps = allowing for higher HP at the higher RPM range. Whereas the Leman's = engine seems to be about 70 degrees ABDC. All accurate. The Lemans engine you should point out, was only turned = up to about 7,600 RPM. So the early closing point was adequate. Most of = the fine work they did was to pump up the mid range so the engine could = have a broad power band. The Lemans circuit has a very slow first gear = corner, and a 230 MPH straightaway. It is typical when fooling with = piston engines to measure degrees of open only after a valve is .050" = off its seat. So little flow is available below that point that it is = not counted. So your cam card will have lobe centers, total lift, lift = minus the valve lash, and timing (measured once the valve is at .050") (Crane gives you duration at running lash as well). For timing I Use oil in the port. When the oil begins to flow I mark = the port as being open.=20 There is nothing to record from a dial indicator or similar that I can = use to determine this as in the piston engines.=20 So, the oil works fine. Without the radius the port would open at a = bit less than 80 degrees. So it is not as exotic as it at first sounds. Secondly, the later the opening event the better ( I understood that = one) because of overlap and contamination of the inlet charge at lower = RPM. Now if we could just close it before we open it, we would be way = ahead - but of course that is not possible, so the squat PP is the next = best shape and timing. So the opening later is better; but the closing later is not good! = As we say in Australia - BUGGER!! =20 Anyhow there is another reference in your response which I don't = quite understand and that is "So even with red lines at or above 8,000 = RPM this modest port closing is more than adequate (this is understood). = If I remember correctly (this becomes less likely with time) " Can = you explain the =20 last=20 sentence about (less likely with time). Do you mean later openings = gave better higher RPM, HP in the racing industry.=20 Nope. It means I am over 65 now and remembering anything is = difficult. LEH TIA George (down under) =20 ************************************** Check out AOL's list of 2007's hottest products. = (http://money.aol.com/special/hot-products-2007?NCID=3Daoltop000300000000= 01)=20 -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.503 / Virus Database: 269.16.17/1179 - Release Date: = 9/12/2007 11:06 AM ------=_NextPart_000_0029_01C83B57.3FDCAF00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 Lynn,
I'm closer to 60 than 59 so I can = relate to that=20 memory thing.
 
That clarifies the timing for me matey = - 70 degrees=20 it is then. I notice that everyone else has followed that trend, moreso = just=20 following where as I have to understand why. I appreciate your = clarification on=20 the subject.
 
Mind you I wouldn't have understand at = all,=20 unless I had set-up the timing wheel, as you originally=20 suggested.
 
Mind you it's a good point to = clarify.
Thanks!
George (down under)
 
BTW have a look at this Aussie Dyno = test - you will=20 recognize the Aussie voices in the background
http://youtube.com/watch?v=3DuO1782B6RZw
Thanks Lynn,

It goes without saying that I always = appreciate your contribution. I may have to refer back to what you = were=20 saying to clarify some points.

I now understand the closing = event has=20 the most effect on the mid range power we need in Aviation (why = is that?=20 and why is your BP closing of 80 degrees flowing very little - there = seems=20 to be plenty of suction still going on?)

The intake closing = event is=20 shown as ABDC. After Bottom Dead Center, in the case of the intake = cycle is in=20 the top of the rotor housing. (a bit confusing) and since BDC for both = intake=20 and exhaust cycles is the largest volume attainable, that closing = point is=20 after the volume is already decreasing. So some of the mixture is = being forced=20 back into the intake manifold. Early closing means more mixture is = trapped in=20 the closing chamber to be used
no matter what the state of tune. So = at=20 lower and medium speeds where inertial charging is low to nonexistant, = the=20 engine still developes some amount of power. The later the closing = point, the=20 more accurate the tune must be to support the same performance down = low, as=20 only high inertia can overcome the mixture being pushed out from the = closing=20 chamber.

So an early closing point captures more mixture, at = lower=20 speeds, and low and medium power is improved. Same as advancing the = cam in a=20 piston engine. Even though it screws up the other three timing = functions, the=20 early closing intake valve makes so much difference it is worth the = work to do=20 it. In a minor way this affects the effective compression ratio as = well. More=20 degrees of closed chamber means higher compression. This becomes = painfully=20 obvious when measuring compression at cranking speeds. My Fiats had = 245 pounds=20 of compression cranking. Run the engine 10 seconds and shut it off = because the=20 NOX would fry you eyes. I could retard the intake cam 5 degrees and = loose 10=20 pounds.


and that closing event should not exceed 70 degrees = ABDC.=20 This is probably something
you told=20 me previously and I hadn't remembered ( or understood properly). = However the=20 Mazda Factory PP is 75 degree IC, perhaps allowing for higher HP at = the=20 higher RPM range. Whereas the Leman's engine seems to be about 70 = degrees=20 ABDC.


All accurate. The Lemans engine you should point out, = was only=20 turned up to about 7,600 RPM. So the early closing point was adequate. = Most of=20 the fine work they did was to pump up the mid range so the engine = could have a=20 broad power band. The Lemans circuit has a very slow first gear = corner, and a=20 230 MPH straightaway. It is typical when fooling with piston engines = to=20 measure degrees of open only after a valve is .050" off its seat. So = little=20 flow is available below that point that it is not counted. So your cam = card=20 will have lobe centers, total lift, lift minus the valve lash, and = timing=20 (measured once the valve is at .050")
(Crane gives you duration at = running=20 lash as well).

For timing I Use oil in the port. When the oil = begins to=20 flow I mark the port as being open.
There is nothing to record = from a dial=20 indicator or similar that I can use to determine this as in the piston = engines.
So, the oil works fine. Without the radius the port would = open at=20 a bit less than 80 degrees.
So it is not as exotic as it at first=20 sounds.


Secondly, the later the opening event the better ( I = understood that one) because of overlap and contamination of the = inlet=20 charge at lower RPM. Now if we could just close it before we open = it, we=20 would be way ahead - but of course that is not possible, so the=20 squat PP is the next best shape and = timing.




So the opening later is better; but the closing = later is not=20 good! As we say in Australia - BUGGER!!
 
Anyhow there is = another=20 reference in your response which I don't quite understand and that = is "So=20 even with red lines at or above 8,000 RPM this modest port closing = is more=20 than adequate (this is understood).

  If I = remember=20 correctly (this becomes less likely with time) " Can you explain=20 the  
  last=20 sentence about (less likely with time). Do you mean = later=20 openings gave better higher RPM, HP in the racing industry.=20

   Nope. It means I am over 65 now and = remembering=20 anything is difficult. LEH

TIA
George (down under)
 




**********= ****************************
Check=20 out AOL's list of 2007's hottest=20 = products.
(http://money.aol.com/special/hot-products-2007?NCID=3Daolto= p00030000000001)=20

No virus found in this incoming message.
Checked by AVG Free = Edition.
Version: 7.5.503 / Virus Database: 269.16.17/1179 - = Release Date:=20 9/12/2007 11:06 AM
 ------=_NextPart_000_0029_01C83B57.3FDCAF00--