X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-qy0-f17.google.com ([209.85.221.17] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with ESMTP id 3482592 for flyrotary@lancaironline.net; Sun, 08 Feb 2009 10:47:05 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.221.17; envelope-from=msteitle@gmail.com Received: by qyk10 with SMTP id 10so2912026qyk.19 for ; Sun, 08 Feb 2009 07:46:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=jMX1RYRs0qXyE0zn+JH7/zf2tYsj0BCqY9OHRTVKAKw=; b=Gt1phX0p3ARNOdyVKRIHucP/6Y8G4YIBAt3z05kNq8azp1+7gkNq8yBJHEzJp16F6/ IoZqdsjv7YPVgWIEXhcgKz7jdchLua5VVytkkFwiir8UMc5quqxv+VhVKfcj8r6r2w7y ZVP8oicHUR07+KaV74oOD1gTKE9GlLxmuZIhU= 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=x+DCpY6MyZGpcI9Rjp42CKlrTHYzuW8TYv79QUUCXO51Z3FF47LFAlK5jVJfAD92bC 77f58Lt+GxuIjZPPhiAW9UyverBdSa621KgHfAIjZt89b2rx4ifK9SmmCrHVK+6U/8PX Z3jhnguXazWbliEf50YJfkPbJVJTLOZ7y6Q8s= MIME-Version: 1.0 Received: by 10.214.181.2 with SMTP id d2mr5290899qaf.380.1234107990080; Sun, 08 Feb 2009 07:46:30 -0800 (PST) In-Reply-To: References: Date: Sun, 8 Feb 2009 09:46:30 -0600 Message-ID: <5cf132c0902080746s66f4cd00n2c8a32e9271fcc06@mail.gmail.com> Subject: Re: [FlyRotary] Exhaust lengths From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015175d673a5cfbb604626a28f0 --0015175d673a5cfbb604626a28f0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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 > --0015175d673a5cfbb604626a28f0 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Lynn,

Thanks for the excellent response.  So, there is sort of= a dynamic tuning effect going on as happens in the 2-rotor intake.  A= ppreciate your sharing 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 ask for quite a while. 

Q:  Do the opti= mum 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 ne= atly laid into the collector one after the other in exactly the same spacin= g. This makes for a good sounding engine, even after muffling. It also make= s for great scavenging, and if the muffler is not too restrictive, can main= tain a low pressure in the exhaust system. That becomes free HP. For exampl= e: I use GE silicone tub and tile caulk on the exhaust header flange. No ga= sket. It need not be high temp anything because it just is never very hot b= eing 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 w= ill leak at idle because velocity is nearing zero.  
 
The lengths are from collections of street headers designed to help st= reet engine build up the rotaries dismal low speed torque. The longer the h= eader 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 yo= u 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 pulse= s will fit in each pipe. And here is the important part.
 
The pipes need to be exactly the same length to the collector. The col= lector needs to be uniform and silk smooth inside. At 6,000 RPM you are ble= nding 12,000 pulses together, or 18,000 pulses from a three rotor, just lik= e cards being shuffled. If you get any two pulses impinging on each other&n= bsp;there will be far less than the very best performance available. Plus t= he 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 tubin= g. I had bends made up and with my abrasive saw I would fit together the he= aders, 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 sh= ove the plastic hose up each pipe to the flat plate gasket over each exhaus= t port. Add masking tape to the hose at the end of the front header, then p= ull 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 cor= rect 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 sys= tem will do. The 4 cylinder engines seem to favor a 32-34 inch header to fl= uff 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 bett= er torque over a wide RPM range. Short, steeply angled collectors produce b= etter torque over a short range of RPM.  
 
The two rotor is two one rotor engines on the same crankshaft. The thr= ee rotor is three one rotor engines on the same crank shaft. The best outco= me is to have both, or all three perform at about the same rate as the othe= rs. 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 rec= overable piece of data. The front housing gets the coldest coolant on one s= ide and the hottest coolant on the other side.  The three rotor (I sus= pect) may have even greater differences). So in those areas where you can g= et the same outcome, you should try to get the same outcome. As in the inta= ke and header lengths. There you go..........
 
15 free HP.
 
Lynn E. Hanover  

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