X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ispmxmta05-srv.windstream.net ([166.102.165.166] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with ESMTP id 3482843 for flyrotary@lancaironline.net; Sun, 08 Feb 2009 14:20:00 -0500 Received-SPF: pass receiver=logan.com; client-ip=166.102.165.166; envelope-from=montyr2157@alltel.net Received: from ispmxaamta08-gx.windstream.net ([98.20.169.0]) by ispmxmta05-srv.windstream.net with ESMTP id <20090208191922.EAUV21050.ispmxmta05-srv.windstream.net@ispmxaamta08-gx.windstream.net> for ; Sun, 8 Feb 2009 13:19:22 -0600 Received: from newbox ([98.20.169.0]) by ispmxaamta08-gx.windstream.net with SMTP id <20090208191922.FZEJ28131.ispmxaamta08-gx.windstream.net@newbox> for ; Sun, 8 Feb 2009 13:19:22 -0600 Message-ID: <02F677C4F81B4F9DAFF3B017A79E452A@newbox> From: "Monty Roberts" To: "Rotary motors in aircraft" Subject: Exhaust lengths Date: Sun, 8 Feb 2009 13:19:21 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0108_01C989EF.DAE5EBA0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Cloudmark-Analysis: v=1.0 c=1 a=Miu1CiupoygZqK5g5sisfw==:17 a=ujJy-M9FrUpRXC553TEA:9 a=yD_eutupDHsuQfy0jecA:7 a=MrR0fD9VyEpIpVGaBk40u2ja5-UA:4 a=tsIYq3Wo7I0A:10 a=ZuF6zLbEb7BNNzCkOF8A:9 a=gHVwkHa513zIByhvrN0A:7 a=GbsuE7t1hInWLejAP-LRgzk4nV0A:4 a=AfD3MYMu9mQA:10 This is a multi-part message in MIME format. ------=_NextPart_000_0108_01C989EF.DAE5EBA0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable FWIW, the people at Racing Beat said that the Renesis is a very = different animal than peripherial exhaust port rotaries when it comes to = exhaust systems. As I recall, they said they got only about an 8 HP = improvement when going from stock (RX-8) exhaust system with cats & the = works, to a full race setup with headers, race mufflers, etc. That is = TINY in comparison to the earlier engines.=20 In other words, the Renesis is very non-critical when it comes to = exhaust systems. Just keep the back pressure down and you'll do pretty = well. At least that was my conclusion. Note there is zero overlap in = intake / exhaust cycles in the Renesis. BTW I'm still waiting for someone to build & test a peripheral intake = port Renesis. I think that would be a great setup for aircraft = applications. =20 Tracy Paul Lamar had a PP Renesis built. I think he got about 240 hp. He used = a carb, and the bsfc was terrible. I'm not sure how good the data was. = There are graphs on his web page. There used to be a youtube vid of it, = but it may be only on his site now.=20 I don't think it is worth fooling with unless you also port the exhaust. = There is enough meat in the four port motor to open it up to the 6 port = exhaust config, but the shape is still terrible. If you look at the port interaction, the path between the exhaust and = intake is so torturous that I'm not sure you would get any crossover = tuning like you do with PP exh. even with the added overlap.=20 With the PP engine you have the glowing hot spaghetti problem to deal = with, and the muffling issue.=20 Monty ------=_NextPart_000_0108_01C989EF.DAE5EBA0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

FWIW, the=20 people at Racing Beat said that the Renesis is a very different animal = than=20 peripherial exhaust port rotaries when it comes to exhaust = systems. As I=20 recall, they said they got only about an 8 HP improvement when going = from stock=20 (RX-8) exhaust system with cats & the works, to a full race setup = with=20 headers, race mufflers, etc. That is TINY in comparison to the = earlier=20 engines.

In other words, the Renesis is very non-critical = when it=20 comes to exhaust systems. Just keep the back pressure down and = you'll do=20 pretty well. At least that was my conclusion. Note there is = zero=20 overlap in intake / exhaust cycles in the Renesis.

BTW I'm still = waiting=20 for someone to build & test a peripheral intake port Renesis. = I think=20 that would be a great setup for aircraft applications. =20

Tracy

Paul Lamar had a PP Renesis built. I = think he got=20 about 240 hp. He used a carb, and the bsfc was terrible. I'm not sure = how good=20 the data was. There are graphs on his web page. There used to = be a=20 youtube vid of it, but it may be only on his = site now.

I don't think it is worth fooling with = unless you=20 also port the exhaust. There is = enough meat=20 in the four port motor to open it up to the 6 port exhaust config, but = the shape=20 is still terrible.

If you look at the port interaction, = the path=20 between the exhaust and intake is so torturous that I'm not sure you = would get=20 any crossover tuning like you do with PP exh. even with the added = overlap.=20

With the PP engine you have the glowing = hot=20 spaghetti problem to deal with, and the muffling issue.

Monty

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