Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b2) with ESMTP id 3184188 for flyrotary@lancaironline.net; Thu, 22 Apr 2004 08:55:32 -0400 Received: from EDWARD (clt25-78-058.carolina.rr.com [24.25.78.58]) by ms-smtp-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i3MCtTkG020306 for ; Thu, 22 Apr 2004 08:55:30 -0400 (EDT) Message-ID: <008901c42869$1890b3b0$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: intake ideas? Date: Thu, 22 Apr 2004 08:55:31 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0086_01C42847.91482530" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0086_01C42847.91482530 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable ----- Original Message -----=20 From: Tracy Crook=20 To: Rotary motors in aircraft=20 Sent: Wednesday, April 21, 2004 10:31 PM Subject: [FlyRotary] Re: intake ideas? At one time I did measure the MAP at the far end of the small = (primary) runners and found a .8" Hg drop at WOT compared to dynamic = chamber reading.=20 At what RPM? This is really what I was after; a feel for the = pressure drop due to flow losses, and trying to understand the nearly = 4=E2=80=9D Hg drop from atmospheric that I measured at 6000 rpm. I am = pulling both ports through a 1.75=E2=80=9D dia, 5=E2=80=9D long TB = barrel, and maybe a bit of loss in the inlet plenum; but not likely that = could account for such a large loss. As you suggested, it must have = something to do with the placement of the measurement port. I may call = the guy at TWM and see what his thoughts are. =20 I expected this drop. For reasons of not wanting to enter a = prolonged and fruitless discussion on rotary engine manifold design, I = will not explain why this drop is desirable : ) Oh; come on =E2=80=93 gives us the 25 words or less version = =E2=80=93 well; maybe 50 words. We promise no prolonged and fruitless = discussion. Al Damn, I'm such a sucker for that line. Most gear heads already understand that successful intake tuning = is the art and science of maximizing and managing the energy represented = by the moving mass of air in the manifold as it accelerates and = decelerates. But, there are some less obvious subtleties at work in the = Mazda rotary manifold. =20 I believe Mazda's intent on the 2nd gen NA rotary was to = intentionally restrict the flow on the primary ports so as to increase = the velocity in the larger secondaries. This goal is also aided by = opening the secondaries a bit sooner than the primaries (gets the train = moving early). Note that porting (enlarging) the primaries or making = the primary runners larger may be counterproductive here so the time = honored tradition of "bigger is better" will lead you the wrong way. = The resultant higher velocity in the secondary runners is then used to = increase VE with the later closing secondary port. So why not close up = the primaries completely and get even higher velocity in the secondary? = It's all about finding the point of diminishing returns. Tracy (way past 50 word limit) Tracy's analysis sounds reasonable to me. Its clear that Mazda = expected some benefit in going to the trouble and expense of keeping the = primary and secondary runners and port timing different. I had wondered = why they would have the secondary port open before the primary port (6 = port engine) and I think Tracy's hypothesis is probably correct - at = least it makes sense. =20 I ported both my primary and secondary to the same port timing = and concluded that since the ports now had the same timing that I could = merge the secondary and primary ports with minimum adverse effect. My = testing will hopefully show that to be correct. Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC ------=_NextPart_000_0086_01C42847.91482530 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
----- Original Message -----
From:=20 Tracy = Crook
Sent: Wednesday, April 21, 2004 = 10:31=20 PM
Subject: [FlyRotary] Re: intake = ideas?

 
 

At one time I did = measure the MAP=20 at the far end of the small (primary) runners and found a = .8" Hg=20 drop at WOT compared to dynamic chamber = reading. 

 

At = what RPM?=20 This is really what I was after; a feel for the pressure drop = due to=20 flow losses, and trying to understand the nearly 4=E2=80=9D Hg = drop from=20 atmospheric that I measured at 6000 rpm.  I am pulling both = ports=20 through a 1.75=E2=80=9D dia, 5=E2=80=9D long TB barrel, and = maybe a bit of loss in the=20 inlet plenum; but not likely that could account for such a large = loss.  As you suggested, it must have something to do with = the=20 placement of the measurement port.  I may call the guy at = TWM and=20 see what his thoughts are.

  =20

 I expected this=20 drop.  For reasons of not wanting to enter a prolonged = and=20 fruitless discussion on rotary engine manifold design, I will = not=20 explain why this drop is desirable : )

Oh; = come on =E2=80=93=20 gives us the 25 words or less version =E2=80=93 well; maybe 50 = words. We promise=20 no prolonged and fruitless discussion.

Al

Damn, I'm such a sucker = for that=20 line.

Most gear = heads already=20 understand that successful = intake tuning=20 is the art and science of maximizing and managing the energy = represented=20 by the moving mass of air in the manifold as it accelerates and=20 decelerates.  But, there are some less=20 obvious subtleties at work in the Mazda rotary = manifold. =20

I believe Mazda's = intent on the 2nd=20 gen NA rotary was to intentionally restrict the flow on the = primary=20 ports so as to increase the velocity in the larger = secondaries. =20 This goal is also aided by opening the secondaries a bit sooner = than the=20 primaries (gets the train moving early).  Note that porting = (enlarging) the primaries or making the primary runners=20 larger may be counterproductive here so the time = honored=20 tradition of "bigger is better" will lead you the wrong = way.  The=20 resultant higher velocity in the secondary runners is = then=20 used to increase VE with the later closing secondary = port.  So=20 why not close up the primaries completely and get even higher = velocity=20 in the secondary?   It's all about finding the point = of=20 diminishing returns.

Tracy  (way past = 50 word=20 limit)

 

Tracy's analysis sounds reasonable to = me. =20 Its clear that Mazda expected some benefit in going to the = trouble and=20 expense of keeping the primary and secondary runners and port = timing=20 different.  I had wondered why they would have the = secondary port=20 open before the primary port (6 port engine) and I think Tracy's = hypothesis is probably correct - at least it makes sense. =20
 
I ported both my primary and secondary = to the same=20 port timing and concluded that since the ports now had the same = timing=20 that I could merge the secondary and primary ports with minimum = adverse=20 effect.  My testing will hopefully show that to be=20 correct.
 
 
Ed Anderson
RV-6A N494BW Rotary=20 Powered
Matthews,=20 = NC
= ------=_NextPart_000_0086_01C42847.91482530--