X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-fx0-f213.google.com ([209.85.220.213] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3882339 for flyrotary@lancaironline.net; Sun, 11 Oct 2009 10:39:45 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.220.213; envelope-from=lehanover@gmail.com Received: by fxm9 with SMTP id 9so7549545fxm.1 for ; Sun, 11 Oct 2009 07:39:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:date:message-id:subject :from:to:content-type; bh=T6YwJ583dqhFFarFSsHqcaC05a6OqpVB0Odr+R9YSsU=; b=ri6asJmvGj+WGf4JjfIEKGCPgNy8G+KaJevCCennQ1lioga2RvXStU3A3HUC7QWaQq xrs91vYLs96GRxlx69F2E4xwfC7BRu5VR47/6Onuaj/jJHkaQp3TR4ZRQpEXpZ/vQqdH kfBDNtxdVDmG6+cLPt4AW/wgItRewe6tqBuhk= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type; b=cKlvwXtmdk8baHTC14fljYlTyhV0tvRr8T/ShVnPnvCQsdOXkd7Dp75iz7Khm6Kvb0 H+aDMf2p5h3EZCZJXeSRgnIe/thMPcaOQRP0KG1cjK8Duvq/kTK30EUZkssjcMl41afF hTvwfj8GvXjdtjewdeSNvOtI68oQ0EBNC9ju8= MIME-Version: 1.0 Received: by 10.204.2.211 with SMTP id 19mr4213080bkk.6.1255271947996; Sun, 11 Oct 2009 07:39:07 -0700 (PDT) Date: Sun, 11 Oct 2009 10:39:07 -0400 Message-ID: <1ab24f410910110739k1b7ee3e0u1fde08f145126900@mail.gmail.com> Subject: The effect of exhaust system design on engine performance. From: Lynn Hanover To: flyrotary@lancaironline.net Content-Type: multipart/alternative; boundary=000e0cd1d6ea8e8f480475a9c6d7 --000e0cd1d6ea8e8f480475a9c6d7 Content-Type: text/plain; charset=ISO-8859-1 Lynn, What is your opinion how power would be effected by splitting the exhaust again for two mufflers after the collector ??................... -- Kelly Troyer "Dyke Delta"_13B ROTARY Engine "RWS"_RD1C/EC2/EM2 "Mistral"_Backplate/Oil Manifold Once the headers are joined in a well designed collector there is only a need to conduct gasses away in the lowest back pressure method available. Two mufflers would offer less back pressure than one of the same design, so two would seem to be better than one. I know that in some cases the collector might work better with a specific length of such and such tubing behind it, in general the collector is the end of exhaust tuning to about 80% of the whole system. Some folks have noticed that they reach full power well before they reach full throttle. On the dyno you often see that this is a function of the butterfly position at full throttle. Too little or too much. And not just the open or closed stops, but over opening may get things spinning in one direction that helps power, and in another intake under opening does the job. So it turns out that full throttle is not the best thing all of the time. However, the dyno has 4 mufflers in parallel and very little back pressure. Some of the systems I have seen on aircraft just makes me want to scream and attack with a hack saw right on the spot. But I have also seen green garden hose in the plumbing on airplanes. So I want to scream allot. The Mistral exhaust I thought would be a masterpiece of clear thinking and execution. Not quite. After the loss of the Piper the pictures of the system were seen on another list. Hopeful would be the best I could say. Closed end pipes with holes out of each port. Enclosed with a big can. Execution was superb. Stainless or Incolnel with all great looking TIG welds. But the number of pieces big enough to block the exit tube was, well everything could have and only one piece is needed. Was needed. The back pressure must have been huge. The big can then just collected whatever escaped from the engine. Sound wise it was effective. For years, model airplane engines were throttled by a simple valve that closed down exhaust flow. Works great, no need to change the carb settings, simple, quiet. Get the picture? The rotary is a 4 stroke Otto cycle engine, and all that means is that it has a specific number of operations in order to function. Beyond that it is just a big dirt bike engine. So like the model airplane engine and the dirt bike engine (2 stroke) it is sensitive to exhaust system tuning, and back pressure. The intake tuning and lengths and diameters and Choke size and Throttle Body size are all important, and rely on the idea that during the opening intake cycle the chamber is at zero or low pressure. So the entire volume of the displacement is available for intake of the next charge. If the exhaust system is sub-par (and all of them are) there will be some leftover exhaust gas in the opening volume. How much is left determines how much intake charge volume can be inducted. In a racing situation the exhaust system will be 3 1/2" or 4" (mine is 4") This was on instruction from the engine builder (Daryl Drummond) to match the system he has on his dyno. The object is too have the escaping exhaust charge produce a vacuum in the chamber so the intake charge "sees" less pressure ahead of it than it "sees" behind it in the induction system. As though there were a little turbo pushing on the intake charge. If you think racing has no application in aircraft do not read further. The Renesis engine has no overlap, so I can have a very restrictive system with no down side. Really? The lack of overlap is just a fact about the intake port and the exhaust port not being open at the same time. This is a real big help when at very low throttle settings and low speed/idle and so-on. It is a change made to reduce HC for California. In the Peoples Republic they have long forgoten why it was called the city of Angles by the Spanish before anyone lived there. The lack of overlap (in the Renesis) or the presence of overlap in other rotaries makes no difference at all in performance when exhaust back pressure is high. In every case, the amount of exhaust gas pressure still trapped in the chamber when the intake port opens determines how much intake volume is available for the next induction cycle. So, if there is just one pound of pressure in the chamber when the intake port opens, the start of intake flow may be delayed, or worse, reverse flow into the intake runner may start things off in the wrong direction. So the effect is what? In effect the engine has been reduced in displacement. The intake port is wide open and no flow in going on for some number of crankshaft degrees, so the first effect is that intake port timing (Open point) is delayed. So the intake port is smaller. The total volume of induction is reduced because the chamber still has exhaust gas in it, So we have lost engine displacement (the engine got smaller). Not the hot rod dream. The up side is that thus contaminated, the charge will burn more slowly and so mimics a higher octane rating along with lower nitrogen oxides. Also lower combustion pressure and lower torque. So little loading on bearings. So, a intake system designed at one end of the building and working perfectly on their dyno must include the exhaust system designed at the other end of the building that is quiet as a mouse in slippers but was never on the dyno with the production intake, or run to destruction in a test cell. In any case the intake volume required by the engine at any particular RPM, may be available well before full throttle is reached. With a high degree of probability.................. Lynn E. Hanover --000e0cd1d6ea8e8f480475a9c6d7 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Lynn,
=A0 What is your opinion how power would be effected by splitting the = exhaust again=A0for two
mufflers after the collector ??...................
--
Kelly Troyer
"Dyke Delta"_13B = ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Back= plate/Oil Manifold
=A0
Once the headers are joined in a well designed col= lector there is only a need to conduct gasses away in the lowest back press= ure method available. Two mufflers would offer less back pressure than one = of the same design, so two would seem to be better than one. I know that in= some cases the collector might work better with a specific length of such = and such tubing behind it, in general the collector is the end of exhaust t= uning to about 80% of the whole system.
=A0
Some folks have noticed that they reach full power= well before they reach full throttle. On the dyno you often see that this = is a function of the butterfly position at full throttle. Too little or too= much. And not just the open or closed stops, but over opening may get thin= gs spinning in one direction that helps power, and in another intake under = opening does the job. So it turns out that full throttle is not the best th= ing all of the time. However, the dyno has 4 mufflers in parallel and very = little back pressure.
=A0
Some of the systems I have seen on aircraft just m= akes me want to scream and attack with a hack saw right on the spot. But I = have also seen green garden hose in the plumbing on airplanes. So I want to= scream allot.
=A0
The Mistral exhaust I thought would be a masterpie= ce of clear thinking and execution. Not quite. After the loss of the Piper = the pictures of the system were seen on another list. Hopeful would be the = best I could say. Closed end pipes with holes out of each port. Enclosed wi= th a big can. Execution was superb. Stainless or Incolnel with all great lo= oking TIG welds.
=A0
But the number of pieces big enough to block the e= xit tube was, well everything could have and only one piece is needed. Was = needed. The back pressure must have been huge. The big can then just collec= ted whatever escaped from the engine. Sound wise it was effective.
=A0
For years, model airplane engines were throttled b= y a simple valve that closed down exhaust flow. Works great, no need to cha= nge the carb settings, simple, quiet. Get the picture?
=A0
The rotary is a 4 stroke Otto cycle engine, and al= l that means is that it has a specific number of operations in order to fun= ction. Beyond that it is just a big dirt bike engine. So like the model air= plane engine and the dirt bike engine (2 stroke) it is sensitive to exhaust= system tuning, and back pressure.
=A0
The intake tuning and lengths and diameters and Ch= oke size and Throttle Body size are all important, and rely on the idea tha= t during the opening intake cycle the chamber is at=A0zero or low pressure.= So the entire volume of the displacement is available for intake=A0of the = next charge. If the exhaust system is sub-par (and all of them are) there w= ill be some leftover exhaust gas in the opening volume. How much is left de= termines how much intake charge volume can be inducted.=A0
=A0
In a racing situation the exhaust system will be 3= 1/2" or 4" (mine is 4") This was on instruction from the en= gine builder (Daryl Drummond) to match the system he has on his dyno. The o= bject is too have the escaping exhaust charge produce a vacuum in the chamb= er so the intake charge "sees" less pressure ahead of it than it = "sees" behind it in the induction system. As though there were a = little turbo pushing on the intake charge.
If you think racing has no application in aircraft= do not read further.
=A0
The Renesis engine has no overlap, so I can have a= very restrictive system with no down side. Really?
=A0
The lack of overlap is just a fact about the intak= e port and the exhaust port not being open at the same time. This is a real= big help when at very low throttle settings and low speed/idle and so-on. = It is a change made to reduce HC for California. In the Peoples Republic th= ey have long forgoten why it was called the city of Angles by the Spanish b= efore anyone lived there.=A0
=A0
The lack of overlap (in the Renesis) or the presen= ce of overlap in other rotaries makes no difference at all in performance w= hen exhaust back pressure is high. =A0In every case, the amount of exhaust = gas pressure still trapped in the chamber when the intake port opens determ= ines how much intake volume is available for the next induction cycle.=A0
=A0
So, if there is just one pound of pressure in the = chamber when the intake port opens, the start of intake flow may be delayed= , or worse, reverse flow into the intake runner may start things off in the= wrong direction.
=A0
So the effect is what?
=A0
In effect the engine has been reduced in displacem= ent. The intake port is wide open and no flow in going on for some number o= f crankshaft degrees, so the first effect is that intake port timing (Open = point) is delayed. So the intake port is smaller. The total volume of induc= tion is reduced because the chamber still has exhaust gas in it, So we have= lost engine displacement (the engine got smaller).=A0Not the hot rod dream= .
=A0
The up side is that thus contaminated, the charge = will burn more slowly and so mimics a higher octane rating along=A0with low= er nitrogen oxides. Also lower combustion pressure and lower torque. So lit= tle loading on bearings.=A0
=A0
So, a intake system designed at one end of the bui= lding and working perfectly on their dyno must include the exhaust system d= esigned at the other end of the building that is quiet as a mouse in slippe= rs but was never on the dyno with the production intake, or run to destruct= ion in a test cell.=A0=A0
=A0
In any case the intake volume required by the engi= ne at any particular RPM, may be available well before full throttle is rea= ched.=A0
=A0
With a high degree of probability.................= .
=A0
Lynn E. Hanover=A0=A0
=A0
=A0
=A0
=A0
=A0
=A0=A0
--000e0cd1d6ea8e8f480475a9c6d7--