X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail23.syd.optusnet.com.au ([211.29.133.164] verified) by logan.com (CommuniGate Pro SMTP 4.3.5) with ESMTPS id 1022467 for flyrotary@lancaironline.net; Sun, 26 Jun 2005 19:49:08 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.133.164; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-107-82.dsl.nsw.optusnet.com.au [211.31.107.82]) by mail23.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id j5QNmH1D018751 for ; Mon, 27 Jun 2005 09:48:19 +1000 Message-ID: <000d01c57aa9$8eba6890$526b1fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Single Rotor Research Date: Mon, 27 Jun 2005 09:48:30 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000A_01C57AFD.5FE7ABA0" 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_000A_01C57AFD.5FE7ABA0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks Lynn - that corresponds to what we discussed previously and = sounds logical. Now the other question - given what you have just stated, is there a = need for a larger exhaust like the Turbo housing exhaust for the mild = 38mm PP . I assume from your explanation, that there isn't and in fact it could be = counter productive! George ( down under) Kelly, Ah so! I wasn't aware of that one and was hoping Lynn would make = some comment. Everything affects everything. Unless there is a need to operate the = engine well above 9,000 RPM, there is no need to modify the exhaust port = to any great extent.=20 Later closing the exhaust port (Port cut taller) extends the open time = and increases overlap with the intake ports. This is quite helpfull at = very high RPM. The same for early opening of the port. (Cuting it lower) = there is little to be lost here at high RPM. The available work left in = the charge has been reduced to near zero, and the late opening is to = help sound by allowing more complete expansion before the charge is = released. Radiusing the opening lip of the port gets flow started along = a smooth curve where much of the flow stays along the bottom of the = runner. There is some interest in removing the exhaust flow completely = before uncovering the intakes. Adding the radius along the opening line = and up the sides of the port does that.=20 Other than removing tooling marks and smoothing the top of the port = there is not much to do. You don't want flow from the top of the port in = either direction. So leave the top as per factory. I would reduce the = chrome and iron around the port in all directions just s few = thousandths to avoid any possibility of snagging an apex seal. Just a = 16th of an inch or so is fine.=20 If a chunk of anything goes through the port you can stand a burr = being stood up or a scratch along the edge of the port. In the stock = situation this would be seen by the next apex seal. If the surface next = to the "hole" has been reduced slightly you may survive that gremlin = without any drama at all. If you want more exhaust flow, you can go wider and not change port = timing at all.=20 The engine suffers from exhaust dilution of the intake charge well = into the RPM range. Adding a big radius to the top of the port opening = would raise the RPM where dilution more or less stops. So I see no point = in changing it much. Lynn E. Hanover Yes your right the top edge of the exhaust port is correct. I had spoken to Lynn in the past on the bottom edge ( leading edge) = but not the top edge - I didn't know he suggested to slightly radius = that edge - if he did I can't remember. If we are singing from the same sheet of music - radiusing the top = edge, does increase exhaust flow characteristics. See attached drawing. Jump inhere if you wish Lynn! George ( down under) George and All, I do not follow !! I am familar with Lynn's suggestion = to add slightly more=20 radius to what I call the top edge of the exhaust port.........Are = you suggesting additional work to this edge ?? Perhaps a simple drawing would = help my simple mind visualize what you are suggesting !! -- Kelly Troyer=20 Dyke Delta/13B/RD1C/EC2=20 ------=_NextPart_000_000A_01C57AFD.5FE7ABA0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Thanks Lynn - that corresponds to what we discussed previously and = sounds=20 logical.
Now the other question - given what you have just stated, is there = a need=20 for a larger exhaust like the Turbo housing exhaust for the mild = 38mm=20 PP
.
I assume from your explanation, that there isn't and in fact it = could be=20 counter productive!
George ( down under)
Kelly,
Ah so! I wasn't aware of that one = and was=20 hoping Lynn would make some = comment.
 
 
Everything affects everything. Unless there is a = need to=20 operate the engine well above 9,000 RPM, there is no need to modify = the=20 exhaust port to any great extent.
 
Later closing the exhaust port (Port cut taller) = extends the=20 open time and increases overlap with the intake ports. This is quite = helpfull=20 at very high RPM. The same for early opening of the port. (Cuting it = lower)=20 there is little to be lost here at high RPM. The available work left = in the=20 charge has been reduced to near zero, and the late opening is to help = sound by=20 allowing more complete expansion before the charge is released. = Radiusing the=20 opening lip of the port gets flow started along a smooth curve where = much of=20 the flow stays along the bottom of the runner. There is some interest = in=20 removing the exhaust flow completely before uncovering the intakes. = Adding the=20 radius along the opening line and up the sides of the port does that.=20
 
Other than removing tooling marks and smoothing = the top of=20 the port there is not much to do. You don't want flow from the top of = the port=20 in either direction. So leave the top as per factory. I would = reduce the=20 chrome and iron  around the port in all directions just s few = thousandths=20 to avoid any possibility of snagging an apex seal. Just a 16th of an = inch or=20 so is fine.
 
If a chunk of anything goes through the port you = can stand a=20 burr being stood up or a scratch along the edge of the port. In the = stock=20 situation this would be seen by the next apex seal. If the = surface next=20 to the "hole" has been reduced slightly you may survive that gremlin = without=20 any drama at all.
 
If you want more exhaust flow, you can go wider = and not=20 change port timing at all.
 
The engine suffers from exhaust dilution of the = intake=20 charge well into the RPM range. Adding a big radius to the top of the = port=20 opening would raise the RPM where dilution more or less stops. So I = see no=20 point in changing it much.
 
Lynn E. Hanover
 
 
 
Yes your right the top edge of the = exhaust port=20 is correct.
I had spoken to Lynn in the past on = the bottom=20 edge ( leading edge) but not the top edge - I didn't know he = suggested to=20 slightly radius that edge - if he did I can't remember.
 
If we are singing from the same = sheet of music=20 - radiusing the top edge, does increase exhaust flow=20 characteristics. See attached drawing.
Jump inhere if you wish = Lynn!
George ( down = under)
George and All,
          I do = not=20 follow !! I am familar with Lynn's suggestion to add slightly more =
radius to what I call the top edge of the exhaust = port.........Are=20 you suggesting
additional work to this edge ?? Perhaps a=20 simple drawing would help my simple
mind visualize what you are suggesting !!
--
Kelly Troyer
Dyke=20 Delta/13B/RD1C/EC2
 
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