X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail01.syd.optusnet.com.au ([211.29.132.182] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTPS id 2573771 for flyrotary@lancaironline.net; Sun, 09 Dec 2007 18:51:12 -0500 Received-SPF: pass receiver=logan.com; client-ip=211.29.132.182; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-119-124.dsl.nsw.optusnet.com.au [211.31.119.124]) by mail01.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id lB9NoN8Y008657 for ; Mon, 10 Dec 2007 10:50:25 +1100 Message-ID: <003601c83abe$477b0160$7c771fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: PP Timing Date: Mon, 10 Dec 2007 09:50:27 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0033_01C83B12.17E78C80" 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_0033_01C83B12.17E78C80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Subject: [FlyRotary] Re: PP Timing In a message dated 12/9/2007 4:32:22 AM Eastern Standard Time, = lendich@optusnet.com.au writes: The inlet timing would be the same ( 85 degrees) - but later, but = not so late as to get into the compression stage, which might cause = further issues. =20 I remember discussing this with someone (it might have been Lynn) = but I can't remember what the negatives are with such a late PP. =20 Can someone put me straight on this again! I hope I got those degrees right! George (down under) Port Timing IO =3D Intake opens IC =3D Intake closes EO =3D Exhaust opens EC =3D Exhaust closes US Model First Generation RX-7 IO 32=B0 ATDC IC 40=B0 ABDC EO 75=B0 BBDC EC 38=B0 ATDC European Model Model First Generation RX-7 IO 32=B0 ATDC IC 50=B0 ABDC EO 75=B0 BBDC EC 48=B0 ATDC First and Second Generation 6-Port 13BPrimary intake (Part = throttle/cruise) IO 32=B0 ATDC IC 40=B0 ABDC Secondary intake (Part to full throttle) IO 32=B0 ATDC IC 30=B0 ABDC Auxiliary high speed ports (Full throttle above approximately 4000 = rpm) IO 45=B0 ATDC IC 70=B0 ABDC EO 71=B0 BBDC EC 48=B0 ATDC Second and Third Generation Turbo 13B IO 32=B0 ATDC IC 50=B0 ABDC EO 71=B0 BBDC EC 48=B0 ATDC Racing Beat "Street Port" IO 25=B0 ATDC IC 60=B0 ABDC EO 84=B0 BBDC EC 48=B0 ATDC Racing Beat "J-Bridge Port" IO 115=B0 BTDC IC 72=B0 ABDC EO 88=B0 BBDC EC 57=B0 ATDC Mazda Factory Peripheral Port IO 86=B0 BTDC IC 75=B0 ABDC EO 73=B0 BBDC EC 65=B0 ATDC This information was copied from Paul Yaws very informative web site = at: WWW.Yawpower.com.=20 You cannot spend too much time reading on this site. I could not get my mind around some of the numbers you cited. I am = setting up a new house in Zephyrhills Florida, and will be building a = new shop here as money becomes available. I have none of my stuff here, = and had to refer to Paul's web page to see the open and close numbers. = This is my wife's computer, and she has nothing about rotaries on it. We will be in Ohio for Christmas and we will keep that house for = summer time.=20 Of the 4 events called out in both piston and rotary engines, the = intake port (or valve) in the piston case, closing point have the = greatest effect on lower to middle range power. This also applies to the = Pport engine. =20 Note: that even the exotic high speed ports on the 6 port engine close = at 70 degrees ABDC. My Bridgeported engine closes at 80 degrees, techically, but is = flowing very little at that point. (big radius and polish job on the = closing line). Extending the closing point to gain HP higher up the RPM = range is fine for a car, or an application where torque can be = mulitplied by some sort of transmission, but the fixed loading of a = propeller may not allow you to wind up to your ideal or near to your = ideal power RPM. So a robust mid range is a must.=20 The side ported engines (even street ported) open the intake port = After BDC. So exhaust dilution is nil. In the Pport engine, this is not = possible. The big hole in the housing will be opening long before the = exhaust port is closed off to any extent, and dilution is going to = happen.=20 From this fact alone I deduce that the intake port should close just = after 70 degrees. That the intake port should open as late as it is = possible to build. The intake port would have a near rectangular shape, = not far removed from a tall looking exhaust port. Even so, the round = port may be flowing so poorly near the open and close points that very = little affect may be noticed. The top of the exhaust port I would leave = stock. I would widen and radius the sides of the port. I would open the = port just a bit early with a slight bow to the centerline, and a = generous radius.=20 The idea here is to minimize overlap.=20 The Pport engine has the pointed rotor tip to open and close the port = /vice the flat side of the rotor. The flow is uninteruped in effect, = with the down side being that the flow is directed right out the exhaust = port, producing the giant fireballs the racers love to generate. The RPM where this shuts off is controlled by the overlap period.=20 Airplane engines operate in the low to middle of the RPM range of the = engine. My bridgeport idles at 2,200 RPM. The hint here is that = automotive like closing points will produce the best airplane engines. A poorly done Pport engine will massively outperform a side port = engine. The Pport will be less happy with exhaust system problems. More = thought to header lengths and muffler design. A function of overlap. = Smaller header tubes rather than larger. Same exact length a must. Same = angle into a collector. Longer rather than shorter.=20 The idea here is to have the port close before a reflected wave can = get back to it. The port numbers I could give you from home are from Mandeville = modified housings that were used up to 10,700 RPM, and that data would = probably be of no value. Sorry. Lynn E. Hanover=20 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?) and that closing event should not exceed 70 degrees = ABDC. This is probably something 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. 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!! 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 last sentence about (less likely with time). Do you mean = later openings gave better higher RPM, HP in the racing industry. TIA George (down under) ------=_NextPart_000_0033_01C83B12.17E78C80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
Subject: [FlyRotary] Re: PP = Timing

In a message dated 12/9/2007 = 4:32:22 AM Eastern=20 Standard Time, lendich@optusnet.com.au=20 writes:

The inlet timing would be the same ( 85 degrees) - but = later,=20 but not so late as to get into the compression stage, which might = cause=20 further issues.
 
I remember = discussing this=20 with someone (it might have been Lynn) but I can't remember what the = negatives are with such a late PP.
  =
Can someone put = me straight on=20 this again!
I hope I got those degrees right!
George (down=20 under)





Port Timing






IO =3D = Intake=20 opens
IC =3D Intake closes
EO =3D Exhaust opens
EC =3D = Exhaust=20 closes

US Model=20 First Generation RX-7
IO 32=B0 ATDC
IC 40=B0 ABDC
EO 75=B0 BBDC
EC = 38=B0=20 ATDC

European=20 Model Model First Generation RX-7
IO 32=B0 = ATDC
IC 50=B0 ABDC
EO=20 75=B0 BBDC
EC 48=B0 ATDC

First and Second = Generation=20 6-Port 13BPrimary=20 intake (Part throttle/cruise)
IO 32=B0 ATDC
IC 40=B0 = ABDC
Secondary=20 intake (Part to full throttle)
IO 32=B0 ATDC
IC 30=B0 = ABDC
Auxiliary high=20 speed ports (Full throttle above approximately 4000 rpm)
IO 45=B0 = ATDC
IC=20 70=B0 ABDC
EO 71=B0 BBDC
EC 48=B0 ATDC

Second and Third = Generation=20 Turbo 13B
IO 32=B0=20 ATDC
IC 50=B0 ABDC
EO 71=B0 BBDC
EC 48=B0 = ATDC

Racing Beat = "Street=20 Port"
IO 25=B0=20 ATDC
IC 60=B0 ABDC
EO 84=B0 BBDC
EC 48=B0 = ATDC

Racing Beat = "J-Bridge=20 Port"
IO 115=B0=20 BTDC
IC 72=B0 ABDC
EO 88=B0 BBDC
EC 57=B0 = ATDC

Mazda Factory = Peripheral=20 Port
IO 86=B0=20 BTDC
IC 75=B0 ABDC
EO 73=B0 BBDC
EC 65=B0 ATDC

This = information was=20 copied from Paul Yaws very informative web site at:

WWW.Yawpower.com.

You cannot = spend too=20 much time reading on this site.

I could not get my mind = around some=20 of the numbers you cited. I am setting up a new house in Zephyrhills = Florida,=20 and will be building a new shop here as money becomes available. I = have none=20 of my stuff here, and had to refer to Paul's web page to see the open = and=20 close numbers. This is my wife's computer, and she has nothing about = rotaries=20 on it.
We will be in Ohio for Christmas and we will keep that house = for=20 summer time.

Of the 4 events called out in both piston and = rotary=20 engines, the intake port (or valve) in the piston case, closing point = have the=20 greatest effect on lower to middle range power. This also applies to = the Pport=20 engine. 

Note: that even the exotic high speed ports on = the 6=20 port engine close at 70 degrees ABDC.
My Bridgeported engine closes = at 80=20 degrees, techically, but is flowing very little at that point. (big = radius and=20 polish job on the closing line). Extending the closing point to gain = HP higher=20 up the RPM range is fine for a car, or an application where torque can = be=20 mulitplied by some sort of transmission, but the fixed loading of a = propeller=20 may not allow you to wind up to your ideal or near to your ideal power = RPM. So=20 a robust mid range is a must.

The side ported engines (even = street=20 ported) open the intake port After BDC. So exhaust dilution is nil. In = the=20 Pport engine, this is not possible. The big hole in the housing will = be=20 opening long before the exhaust port is closed off to any extent, and = dilution=20 is going to happen.

From this fact alone I deduce that the = intake port=20 should close just after 70 degrees. That the intake port should open = as late=20 as it is possible to build. The intake port would have a near = rectangular=20 shape, not far removed from a tall looking exhaust port. Even so, the = round=20 port may be flowing so poorly near the open and close points that very = little  affect may be noticed. The top of the exhaust port I = would leave=20 stock. I would widen and radius the sides of the port. I would open = the port=20 just a bit early with a slight bow to the centerline, and a generous = radius.=20

The idea here is to minimize overlap.

The Pport = engine=20 has the pointed rotor tip to open and close the port /vice the flat = side of=20 the rotor. The flow is uninteruped in effect, with the down side being = that=20 the flow is directed right out the exhaust port, producing the giant = fireballs=20 the racers love to generate.

The RPM where this shuts off is = controlled=20 by the overlap period.

Airplane engines operate in the low to = middle=20 of the RPM range of the engine.  My bridgeport idles at 2,200 = RPM. The=20 hint here is that automotive like closing points will produce the best = airplane engines.

A poorly done Pport engine will massively = outperform=20 a side port engine. The Pport will be less happy with exhaust system = problems.=20 More thought to header lengths and muffler design. A function of = overlap.=20 Smaller header tubes rather than larger. Same exact length a must. = Same angle=20 into a collector. Longer rather than shorter.

The idea here is = to have=20 the port close before a reflected wave can get back to it.

The = port=20 numbers I could give you from home are from Mandeville modified = housings that=20 were used up to 10,700 RPM, and that data would probably be of no=20 value.

Sorry.

Lynn E. Hanover

Thanks = Lynn,

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

I now=20 understand the closing event has the most effect on the mid range = power we=20 need in Aviation (why is that? and why is your BP closing of = 80=20 degrees flowing very little - there seems to be plenty of suction = still going=20 on?) and that closing event should not exceed 70 degrees = ABDC. This=20 is probably something you told me previously and I hadn't remembered ( = or=20 understood properly). However the Mazda Factory PP is 75 degree IC, = perhaps=20 allowing for higher HP at the higher RPM range. Whereas the = Leman's=20 engine seems to be about 70 degrees ABDC.

Secondly, the = later the opening=20 event the better ( I understood that one) because of overlap and = contamination=20 of the inlet charge at lower RPM. Now if we could just close it before = we open=20 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=20 good! As we say in Australia - BUGGER!!
 
Anyhow there is another reference in your response = which I=20 don't quite understand and that is "So even with red lines at or above = 8,000=20 RPM this modest port closing is more than adequate (this is=20 understood). If I remember correctly (this becomes less = likely with=20 time) " Can you explain the last sentence about (less likely with = time). Do=20 you mean later openings gave better higher RPM, HP in the racing=20 industry.
TIA
George (down under)
 
 


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