X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qw-out-2122.google.com ([74.125.92.25] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with ESMTP id 3482757 for flyrotary@lancaironline.net; Sun, 08 Feb 2009 12:40:59 -0500 Received-SPF: pass receiver=logan.com; client-ip=74.125.92.25; envelope-from=rwstracy@gmail.com Received: by qw-out-2122.google.com with SMTP id 5so429631qwd.25 for ; Sun, 08 Feb 2009 09:40:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to :content-type; bh=pXIrfNX13iquN1yhcitl/UgrU8zaKMUnfVRX1aSaHzQ=; b=X49+l/qFWvyJ6tQIcXGcyvcrWyJ5LrhgeGJ+1iYP6wyqvxSwCEm2GVQzRDFcVuNtKk dt5D2pZWQ5ntzDcE096Ok1Z9x3NKlFezvhez9UQjPB0ard1sbAmLEiGlpEnQj5E0wLZV wrcfqtx2HOHheAyADSbDaQAyow+gE0YhwD9Mg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=IvfdaQb6HV2E5gvsb/ZpjbLt0XiH/8iapnlT5l40LIIN3UMiIiWLUr/HhMGnEXnyNL byDuYJSbMohEjP1mftVIUqY2PUK7Mwsk/6CmUcckiwJTQ6XRP/y6whPY0KyoYEY9fV4G Y6/K8wydFgD+ETJxohJp/OJAaD0XSFpqQe6C0= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.215.66.9 with SMTP id t9mr5443352qak.214.1234114823889; Sun, 08 Feb 2009 09:40:23 -0800 (PST) In-Reply-To: References: Date: Sun, 8 Feb 2009 12:40:23 -0500 X-Google-Sender-Auth: f6b656621d0b1c27 Message-ID: <1b4b137c0902080940p748ebd01x953f9ecedcf3eab9@mail.gmail.com> Subject: Re: [FlyRotary] Re: Exhaust lengths From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015175cf7eeb0a5a704626bbfb7 --0015175cf7eeb0a5a704626bbfb7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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. 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. Tracy On Sun, Feb 8, 2009 at 12:13 PM, The Mallorys wrote: > Lynn, > > Thanks for the info. So it looks like the total length after the collector > doesn't really matter. I'm using the stock Renesis tubing up to the 180* > bend, so I'm assuming(maybe incorrectly) that they have done the math and > have the lengths right. > > > > Chris > > > > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] *On > Behalf Of *Mark Steitle > *Sent:* Sunday, February 08, 2009 9:47 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Exhaust lengths > > > > Lynn, > > Thanks for the excellent response. So, there is sort of a dynamic tuning > effect going on as happens in the 2-rotor intake. Appreciate your sharing > your knowledge with the group. > > Mark S. > > On Sun, Feb 8, 2009 at 8:10 AM, Lynn Hanover wrote: > > Lynn, > > I have a question regarding exhaust/inlet lengths that I've wanted to ask > for quite a while. > > Q: Do the optimum lengths of 12/24/36/102 hold true only for the 2-rotor > engines or does it work for the 3-rotor engines too? > > Mark S. > > > > The object of the headers, is that the supersonic pulses need to be neatly > laid into the collector one after the other in exactly the same spacing. > This makes for a good sounding engine, even after muffling. It also makes > for great scavenging, and if the muffler is not too restrictive, can > maintain a low pressure in the exhaust system. That becomes free HP. For > example: I use GE silicone tub and tile caulk on the exhaust header flange. > No gasket. It need not be high temp anything because it just is never very > hot being clamped to the rotor housing. There is no pressure at all to deal > with in this junction, as the supersonic flow is well below sea level > pressure (One Barr). If it did ever leak it would draw in local air into the > header pipe, and make cracking sounds on closed throttle. If it leaks at > all, it will leak at idle because velocity is nearing zero. > > > > The lengths are from collections of street headers designed to help street > engine build up the rotaries dismal low speed torque. The longer the header > pipes the more solid the slugs from each firing event, and the better the > scavenging and low end torque. > > > > Once you have a 11" of header, you have two full pulses from each housing > and if you collect them with the exact same length of pipe you have done as > much as you need for anything over 3,000 RPM. As the revs go higher, the > headers (In effect) become longer because more full pulses will fit in each > pipe. And here is the important part. > > > > The pipes need to be exactly the same length to the collector. The > collector needs to be uniform and silk smooth inside. At 6,000 RPM you are > blending 12,000 pulses together, or 18,000 pulses from a three rotor, just > like cards being shuffled. If you get any two pulses impinging on each > other there will be far less than the very best performance available. Plus > the engine will be annoying. Too loud but sounds great entering the pattern > is way better than nobody talks to you, and Jimmy's dog won't come out from > under the truck. > > > > I had a length of corrigated plastic hose looking stuff, used to cover > bundles of wire in trucks. It just fit inside of 1 7/8" ID tubing. I had > bends made up and with my abrasive saw I would fit together the headers, > tacking on pieces and fitting them into the spaces as I went along. I > smoothed the joints inside just as though each piece would be a finished > piece. Once at the collector. (both pipes parallel for 3 inches) I would > shove the plastic hose up each pipe to the flat plate gasket over each > exhaust port. Add masking tape to the hose at the end of the front header, > then pull it out and shove in the rear header, to see where the tape ended > up. It is easy to lengthen and shorten the straight runs out of the flange > to correct small differences in length. > > > > I am not trying to tune the engine with header length. Just trying to get > the exhaust out without screwing away any HP that a poorly designed system > will do. The 4 cylinder engines seem to favor a 32-34 inch header to fluff > up the torque that a big cam will take away. So if you need help in a 4 > cylinder from 3,000 to 4,500 there is your header length. I used 24" because > the engine builder uses that on the dyno. It is typical to have two nodes > where any paticular header length will add a bit of power. The lower of the > two is seldom high enough to use for anything but a street engine. > > > > Just as in piston engines, long, shallow angle collectors produce better > torque over a wide RPM range. Short, steeply angled collectors produce > better torque over a short range of RPM. > > > > The two rotor is two one rotor engines on the same crankshaft. The three > rotor is three one rotor engines on the same crank shaft. The best outcome > is to have both, or all three perform at about the same rate as the others. > You will notice that there seem to be complaints as to EGT, water temps, > compression, vibration fuel flow, exhaust color, and so on with every > recoverable piece of data. The front housing gets the coldest coolant on one > side and the hottest coolant on the other side. The three rotor (I suspect) > may have even greater differences). So in those areas where you can get the > same outcome, you should try to get the same outcome. As in the intake and > header lengths. There you go.......... > > > > 15 free HP. > > > > Lynn E. Hanover > > > --0015175cf7eeb0a5a704626bbfb7 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable FWIW, the people at Racing Beat said that the Renesis is a very different a= nimal than peripherial exhaust port rotaries when it comes to exhaust syste= ms.  As I recall, they said they got only about an 8 HP improvement wh= en going from stock (RX-8) exhaust system with cats & the works, to a f= ull race setup with headers, race mufflers, etc.  That is TINY in comp= arison to the earlier engines.

 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 zer= o 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. 

Tracy

On Sun= , Feb 8, 2009 at 12:13 PM, The Mallorys <candtmallory@cebridge.net> wr= ote:

Lynn,

Thanks for the= info.  So it looks like the total length after the collector doesn't really matter.  I'm using the stock Renesis tubing u= p to the 180* bend, so I'm assuming(maybe incorrectly) that they have done the math = and have the lengths right.

 <= /p>

Chris

 <= /p>

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle Sent: Sunday, February 08, 2009 9:47 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Exhaust lengths

 

Lynn,

Thanks for the excellent response.  So, there is sort of a dynamic tun= ing effect going on as happens in the 2-rotor intake.  Appreciate your sha= ring your knowledge with the group.

Mark S.

On Sun, Feb 8, 2009 at 8:10 AM, Lynn Hanover <lehanover@gmail.com> wrote:

Lynn,

I have a question regarding exhaust/inlet lengths that I've wanted to a= sk for quite a while. 

Q:  Do the optimum lengths of 12/24/36/102 hold true only for the 2-ro= tor engines or does it work for the 3-rotor engines too?

Mark S. 

 

The object of the headers, is that the supersonic pulses need to be neatly laid into the collector one after the other in exactly th= e same spacing. This makes for a good sounding engine, even after muffling. I= t also makes for great scavenging, and if the muffler is not too restrictive,= can maintain a low pressure in the exhaust system. That becomes free HP. For example: I use GE silicone tub and tile caulk on the exhaust header flange.= No gasket. It need not be high temp anything because it just is never very hot being clamped to the rotor housing. There is no pressure at all to deal wit= h in this junction, as the supersonic flow is well below sea level pressure (One Barr). If it did ever leak it would draw in local air into the header pipe,= and make cracking sounds on closed throttle. If it leaks at all, it will leak a= t idle because velocity is nearing zero.  

 

The lengths are from collections of street headers designed to help street engine build up the rotaries dismal low speed torque. The lo= nger the header pipes the more solid the slugs from each firing event, and the better the scavenging and low end torque. 

 

Once you have a 11" of header, you have two full pulses from each housing and if you collect them with the exact same length= of pipe you have done as much as you need for anything over 3,000 RPM. As the = revs go higher, the headers (In effect) become longer because more full pul= ses will fit in each pipe. And here is the important part.

 

The pipes need to be exactly the same length to the collector. The collector needs to be uniform and silk smooth inside. At 6,0= 00 RPM you are blending 12,000 pulses together, or 18,000 pulses from a three rotor, just like cards being shuffled. If you get any two pulses impinging = on each other there will be far less than the very best performance available. Plus the engine will be annoying. Too loud but sounds great ente= ring the pattern is way better than nobody talks to you, and Jimmy's dog won= 't come out from under the truck.

 

I had a length of corrigated plastic hose looking stuff, used to cover bundles of wire in trucks. It just fit inside of 1 7/8&q= uot; ID tubing. I had bends made up and with my abrasive saw I would fit togethe= r the headers, tacking on pieces and fitting them into the spaces as I went along. I smoothed the joints inside just as though each piece would be a finished piece. Once at the collector. (both pipes parallel for 3 inches) I would shove the plastic hose up each pipe to the flat plate gasket over eac= h exhaust port. Add masking tape to the hose at the end of the front header, = then pull it out and shove in the rear header, to see where the tape ended up. I= t is easy to lengthen and shorten the straight runs out of the flange to correct small differences in length. 

 

I am not trying to tune the engine with header length. Just trying to get the exhaust out without screwing away any HP that a poorly designed system will do. The 4 cylinder engines seem to favor a 32-34 inch header to fluff up the torque that a big cam will take away. So if you need help in a 4 cylinder from 3,000 to 4,500 there is your header length. I use= d 24" because the engine builder uses that on the dyno. It is typical to have two nodes where any paticular header length will add a bit of power. T= he lower of the two is seldom high enough to use for anything but a street eng= ine.

 

Just as in piston engines, long, shallow angle collectors produce better torque over a wide RPM range. Short, steeply angled collecto= rs produce better torque over a short range of RPM.  

 

The two rotor is two one rotor engines on the same crankshaft. The three rotor is three one rotor engines on the same crank sh= aft. The best outcome is to have both, or all three perform at about the same ra= te as the others. You will notice that there seem to be complaints as to EGT, water temps, compression, vibration fuel flow, exhaust color, and so on wit= h every recoverable piece of data. The front housing gets the coldest coolant= on one side and the hottest coolant on the other side.  The three rotor (= I suspect) may have even greater differences). So in those areas where you ca= n get the same outcome, you should try to get the same outcome. As in the int= ake and header lengths. There you go..........

 

15 free HP.

 

Lynn E. Hanover  

 


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