X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-ew0-f52.google.com ([209.85.215.52] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4598522 for flyrotary@lancaironline.net; Wed, 01 Dec 2010 11:37:27 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.52; envelope-from=msteitle@gmail.com Received: by ewy23 with SMTP id 23so4429657ewy.25 for ; Wed, 01 Dec 2010 08:36:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=jGt/poC5nzc6H+FxfPr7zGvIiAu1h3D/ZEwxHkSOTjE=; b=VcxstyrnBm6uLunpZAYu32N0K9Ezymo4ejBXoTmIg4+3bJNgDhYps2+bPFypFkJEtd agQTNYaqaJyyOtWeLE+XmC1z5dHeHppd+rA/u48lcoAIjFxIxpjienFH7vlgKqU1/IXv J1mWCbCCTFReusXQ2jovfGFgTBg8bOhfAWueU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=s/G2RjILrWxcIhojKo37m79EKChXzb3wjeir+uIgQdfNM7urxM++1rblpfKqerZKOc FIAbdyl448RIkC3Yw/L540TL60VWQnX//L+Fg670ykoqewtLSNaY4bqpXqDWDTnmgzFS 1UneSkaDvajQWAImfkknrQBYfFOqsILDK3c5Y= MIME-Version: 1.0 Received: by 10.213.26.15 with SMTP id b15mr5843861ebc.13.1291221409401; Wed, 01 Dec 2010 08:36:49 -0800 (PST) Received: by 10.213.34.212 with HTTP; Wed, 1 Dec 2010 08:36:49 -0800 (PST) In-Reply-To: References: Date: Wed, 1 Dec 2010 10:36:49 -0600 Message-ID: Subject: Re: [FlyRotary] Modified header Calculations From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015174a050a6f31b804965be9d0 --0015174a050a6f31b804965be9d0 Content-Type: text/plain; charset=ISO-8859-1 Ed, It took a while, but my copy of *Street Rotary - How to Build Maximum Horsepower & Reliability into Mazda's 12A, 13B & Renesis Engines* finally arrived yesterday. Thanks for the recommendation. Lots of good info, everyone on the list ought to order a copy and read it from cover to cover, except for Lynn H. - he ought to write his own book on rotary engines. (I'd buy the first copy.) As you suggested, I've been reading the chapter on exhaust systems. I found a paragraph that is right on target relating to what we've been discussing (exhaust system restriction). They compare a 2-rotor wankel to a 2 cylinder 4-stroke *where both cylinders share the same exhaust port. * Quote, "...the exhaust system on a 12A or 13B rotary engine is roughly analogous to a two-cylinder piston engine in which both cylinders are served by a single exhaust port. If cylinder #1 was in overlap period, and the exhaust valve of the #2 cylinder then opened, high pressure gas would flow from the #2 to #1 cylinders. A highly restrictive exhaust system would aggravate the situation. This, the authors point out, is the major reason why a free-flowing exhaust system is so important in a rotary engine." This explains why I saw such an improvement when switching exhaust systems. There is also much discussion on primary header length. Disregarding the "long" header system as we don't have the room, the "short" header length shown for a p-port engine is between 10 and 18 inches. So, your calculations for header length seem to be right in the ballpark. Now I have to figure how to get the three very short primary tubes of 11 3/4" to meet on the same tangent at the collector. Finally, I liked their comment regarding the peripheral ported engines. It reads, *"Traditionally relegated to speciality race cars, occasionally a peripherally ported engine finds its way onto the street in some high-performance vehicle. These engines are not, however, for the faint of heart."* LOL Not to worry, my heart is strong! Mark On Sun, Nov 21, 2010 at 7:53 AM, Ed Anderson wrote: > Mark, > > I did some additional reading in the rotary book I recommended to you and a > bit more head scratching on exhaust systems. > > I modified the tube length formula I used earlier to compensate for the > fact the rotary puts out two exhaust pulses per port per 720 deg cycle > compared to 1 for the piston engine. This in effect halved the length of > tube needed to get the same scavenging effect. > > Also using the recommended rotary book values for area of a rotary exhaust > tube , I calculated the tube diameter which came out to 1.8". > > In any case, I have attached the spreadsheet with those modifications > > Ed > > > Edward L. Anderson > Anderson Electronic Enterprises LLC > 305 Reefton Road > Weddington, NC 28104 > http://www.andersonee.com > http://www.eicommander.com > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > > --0015174a050a6f31b804965be9d0 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Ed,
=A0
It took a while, but my copy of=A0Street Rotary - How to=A0Build Ma= ximum Horsepower & Reliability into Mazda's 12A, 13B & Renesis = Engines=A0finally arrived yesterday.=A0 Thanks for the recommendation.= =A0 Lots of good info, everyone on the list ought to order a copy and read = it from cover to cover, except for Lynn H. - he ought to write=A0his own=A0= book on rotary engines.=A0 (I'd buy the first copy.)=A0
=A0
As you suggested, I've been reading the chapter on exhaust systems= .=A0 I found a paragraph that is right on target relating to what we've= been discussing (exhaust system restriction).=A0 They compare a 2-rotor wa= nkel to a 2 cylinder 4-stroke=A0where both cylinders share the same= exhaust port.=A0
=A0
Quote, "...the exhaust system on a 12A or 13B rotary engine is ro= ughly analogous to a two-cylinder piston engine in which both cylinders are= served by a single exhaust port.=A0 If cylinder #1 was in overlap period, = and the exhaust valve of the #2 cylinder then opened, high pressure gas wou= ld flow from the #2 to #1 cylinders.=A0 A highly restrictive exhaust system= would aggravate the situation.=A0 This, the authors point out, is the majo= r reason why a free-flowing exhaust system is so important in a rotary engi= ne."=A0 This explains why I saw such an improvement when switching exh= aust systems.=A0
=A0
There is also much discussion on primary header length.=A0 Disregardin= g the "long" header system as we don't have the room, the &qu= ot;short" header length shown for a p-port engine is between 10 and 18= inches.=A0 So, your calculations for header length seem to be right in the= ballpark.=A0 Now I have to figure how to get the three very short primary = tubes of 11 3/4" to meet=A0on the same tangent at the collector.=A0
=A0
Finally, I liked their comment=A0regarding the peripheral ported engin= es.=A0 It reads,=A0"Traditionally relegated to speciality race= cars, occasionally a peripherally ported engine finds its way onto the str= eet in some high-performance vehicle. These engines are not, however, for t= he faint of heart."=A0 LOL=A0 Not to worry, my heart is stron= g!=A0
=A0=A0
Mark

On Sun, Nov 21, 2010 at 7:53 AM, Ed Anderson <eanderson@c= arolina.rr.com> wrote:
Mark,
=A0
I did some additional reading in the rotary book = I recommended to you and a bit more head scratching on exhaust systems.
=A0
I modified the tube length=A0formula I=A0used ear= lier to compensate for the fact the rotary puts out two exhaust pulses per = port per 720 deg cycle compared to 1 for the piston engine.=A0 This in effe= ct halved the length of tube needed to get the same scavenging effect.
=A0
Also using the recommended rotary =A0book values = for area of a rotary exhaust tube=A0, I calculated the tube diameter which = came out to 1.8".=A0
=A0
In any case, I have attached the spreadsheet with= those modifications
=A0
Ed
=A0
=A0
Edward L. Anderson
Anderson Electronic Enterpr= ises LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com

--
Hom= epage: =A0http://ww= w.flyrotary.com/
Archive and UnSub: =A0 http://mail.lancaironline.net:81/lists= /flyrotary/List.html


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