Return-Path: Received: from swan.mail.pas.earthlink.net ([207.217.120.123] verified) by logan.com (CommuniGate Pro SMTP 4.1.3) with ESMTP id 2585290 for flyrotary@lancaironline.net; Fri, 19 Sep 2003 00:49:24 -0400 Received: from user-2injqp4.dialup.mindspring.com ([165.121.235.36] helo=Carol) by swan.mail.pas.earthlink.net with smtp (Exim 3.33 #1) id 1A0DCr-0001Qi-00 for flyrotary@lancaironline.net; Thu, 18 Sep 2003 21:49:21 -0700 Message-ID: <006901c37e69$58bdb780$0000a398@Carol> From: "sqpilot@earthlink" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Intake questions Date: Thu, 18 Sep 2003 23:49:00 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0066_01C37E3F.6F1F7D80" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2720.3000 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2727.1300 This is a multi-part message in MIME format. ------=_NextPart_000_0066_01C37E3F.6F1F7D80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Thursday, September 18, 2003 2:15 PM Subject: [FlyRotary] Re: Intake questions Subject: [FlyRotary] Re: Intake questions Hi, Rusty.....I purchased the short intake manifold from Dave = Atkins. He claims he has more than adequate power with his, and that = idle is also good. Look at all the race cars and racing motorcycles = that have the carbs or throttle bodies right next to the engine. They = seem to generate a lot of power that way. For what it's worth. Paul = Conner=20 I originally had planned on longer 'tuned' runners, Dave Atkins made = all the arguments to me about his short manifold being just as good, = etc.,etc. I wanted to believe because I liked the idea of a short = compact manifold for my installation; so I designed and had made a very = nice short, compact manifold.=20 I have since done the dyno runs on my engine, and compared data from = different sources. I haven't delved into the theory as much as Ed; I've = come to a conclusion. High rpm operation; say 7000+ likes a short = compact manifold because at those rpms the tuned length is very short, = but also because the ease of breathing is what matters. Dave Atkins = doesn't know the theory well at all, he knows about performance of drag = racing engines and others; and I'd say mostly at higher rpm. And, of = course Lyn is right as well, racing at 9000 rpm, short manifold is best. = =20 In the case of my engine the hp curve just kept going up to my end = point of 7000 rpm where it reached 95 hp per rotor. But I was = disappointed (just a little bit) by the hp at 5500 of 78.5/rotor). It's = really hard to find good real dyno data for comparison, but my educated = guess is that I might get 3 - 5 more hp per rotor somewhere in the 5000 = - 5500 rpm range with longer tuned runners. I'd probably get about the = same, or a little less at 7000. Dave also argued that the 9:1 compression rotors that he put in (for = normally aspirated) were just as good as 9.5:1. I never did really = believe that; but again, the data shows that at higher rpm he's probably = right. Curves that Mazda generated show that above about 6800 or so, = that compression ratio doesn't matter; but at 5500 rpm it could mean = another 3 - 4 hp per rotor. So, in my case, tuned induction (done = correctly) and the 9.5:1 rotors might give me 85 - 87 hp per rotor at = 5500. So for a N/A engine and a 2.17:1 redrive ratio these factors matter. = For turbocharged and higher rpm it doesn't; just make it breath easy. = Any gain from tuned induction effect can easily be achieved with just a = bit more boost. At least that's my take. Al=20 Hi, Al....and thanks for the education and work on the dyno. I = guess I'm kinda thinking that I would be pretty happy with 78.5 hp per = rotor at 5500 rpm. That's nearly 160 hp on auto fuel with a = bullet-proof engine that I can rebuild for less than the cost of one = cylinder kit for a Lycoming....hmmmm....not too shabby. It a tuned intake might give another 3 to 5 hp increase per = rotor, I'm not entirely sure I'd go through the extra effort and = expense, versus a simple, straight bolt-on manifold that fits just right = inside my cowling, with no modifications, plus it is very light weight. = My aircraft, being a canard, is pretty clean aerodynamically, and I = think that 5500 rpm might give me reasonable fuel burns properly leaned = out, and the engine won't be working all that hard at those rpm's? I'm = far more interested in fuel economy at cruise than high performance = climb-outs. I figure I spend 95 percent of my flight at cruise, and = only 5 percent on take-off and climb, so my priorities are for low rpm, = economical cruise performance. After I receive this new manifold, I may = have a couple aluminum tubes bent and have longer intake runners, won't = know until I receive the new intake manifold. Will keep you posted. = Thanks again for all your input and information. sincerly, Paul Conner ------=_NextPart_000_0066_01C37E3F.6F1F7D80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
 
----- Original Message -----
From:=20 Al = Gietzen=20
Sent: Thursday, September 18, = 2003 2:15=20 PM
Subject: [FlyRotary] Re: Intake = questions

 

Subject:=20 [FlyRotary] Re: Intake questions

 

Hi, Rusty.....I = purchased the=20 short intake manifold from Dave Atkins. He claims he has more than = adequate=20 power with his, and that idle is also good.  Look at all the = race cars=20 and racing motorcycles that have the carbs or throttle bodies right = next to=20 the engine.  They seem to generate a lot of power that way. For = what=20 it's worth. Paul Conner 

 

I = originally had=20 planned on longer =91tuned=92 runners, Dave Atkins made all the = arguments to me=20 about his short manifold being just as good, etc.,etc.  I = wanted to=20 believe because I liked the idea of a short compact manifold for my=20 installation; so I designed and had made a very nice short, compact=20 manifold.

 

I have = since done=20 the dyno runs on my engine, and compared data from different = sources. I=20 haven=92t delved into the theory as much as Ed; I=92ve come to a = conclusion.=20 High rpm operation; say 7000+ likes a short compact manifold because = at=20 those rpms the tuned length is very short, but also because the ease = of=20 breathing is what matters. Dave Atkins doesn=92t know the theory = well at all,=20 he knows about performance of drag racing engines and others; and = I=92d say=20 mostly at higher rpm.  And, of course Lyn is right as well, = racing at=20 9000 rpm, short manifold is best.  

 

In the = case of my=20 engine the hp curve just kept going up to my end point of 7000 rpm = where it=20 reached 95 hp per rotor.  But I was disappointed (just a little = bit) by=20 the hp at 5500 of 78.5/rotor).  It=92s really hard to find good = real dyno=20 data for comparison, but my educated guess is that I might get 3 - 5 =  more hp per rotor somewhere in the 5000 =96 5500 rpm range = with longer=20 tuned runners.  I=92d probably get about the same, or a little = less at=20 7000.

 

Dave = also argued=20 that the 9:1 compression rotors that he put in (for normally = aspirated) were=20 just as good as 9.5:1.  I never did really believe that; but = again, the=20 data shows that at higher rpm he=92s probably right.  Curves = that Mazda=20 generated show that above about 6800 or so, that compression ratio = doesn=92t=20 matter; but at 5500 rpm it could mean another 3 =96 4 hp per = rotor.  So,=20 in my case, tuned induction (done correctly) and the 9.5:1 rotors = might give=20 me 85 =96 87 hp per rotor at 5500.

 

So for = a N/A=20 engine and a 2.17:1 redrive ratio these factors matter.  For=20 turbocharged and higher rpm it doesn=92t; just make it breath easy. = Any gain=20 from tuned induction effect can easily be achieved with just a bit = more=20 boost.

 

At = least that=92s=20 my take.

 

Al=20

Hi, = Al....and=20 thanks for the education and work on the dyno.  I guess I'm = kinda=20 thinking that I would be pretty happy with 78.5 hp per rotor at 5500 = rpm.  That's nearly 160 hp on auto fuel with a bullet-proof = engine that=20 I can rebuild for less than the cost of one cylinder kit for a=20 Lycoming....hmmmm....not too shabby.

     =20 It a tuned intake might give another 3 to 5 hp increase per rotor, = I'm not=20 entirely sure I'd go through the extra effort and expense, versus a = simple,=20 straight bolt-on manifold that fits just right inside my cowling, = with no=20 modifications, plus it is very light weight.  My aircraft, = being a=20 canard, is pretty clean aerodynamically, and I think that 5500 rpm = might=20 give me reasonable fuel burns properly leaned out, and the engine = won't be=20 working all that hard at those rpm's?  I'm far more = interested in=20 fuel economy at cruise than high performance climb-outs.  I = figure I=20 spend 95 percent of my flight at cruise, and only 5 percent on = take-off and=20 climb, so my priorities are for  low rpm, economical cruise=20 performance.  After I receive this new manifold, I may have a = couple=20 aluminum tubes bent and have longer intake runners, won't know until = I=20 receive the new intake manifold.  Will keep you posted.  = Thanks=20 again for all your input and information.  sincerly,  Paul = = Conner

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