Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 3226166 for flyrotary@lancaironline.net; Tue, 11 May 2004 08:21:47 -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 i4BCLjkG001110 for ; Tue, 11 May 2004 08:21:46 -0400 (EDT) Message-ID: <003001c43752$86c240e0$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Runner Length Was Ref: injector relocation predictions? Date: Tue, 11 May 2004 08:21:45 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002D_01C43730.FF7C4A70" 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_002D_01C43730.FF7C4A70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Monday, May 10, 2004 9:33 PM Subject: [FlyRotary] injector relocation predictions? Greetings, As I mentioned before, one of the relatively easy options for = improvement will be to move the 4 injectors, and keep the current = intake. As they are now, all 4 injectors are in the TB, which is 30 = inches away on the cold side of the engine. I believe I can mount the = two stock primaries back in the block, and can probably mount the two = secondaries in the intake, maybe 2 inches from the engine. =20 Here's the question, do you think this will increase power? In other = words, am I losing power by having the injectors coating the inside of = the long tubing, rather than efficiently delivering the fuel to the = engine? =20 Thanks, Rusty (thinking of draining one fuel tank, and filling it with helium = to improve climb) =20 Rusty, I don't think anyone can answer that question - depends on too = many variables. You would think that even if the fuel coated your long = runners that eventually it ends up in the combustion chamber. My = (admittedly limited) experience with rotary intakes leads me to believe = that the number one, primary, uno, far outweighing all other factors, = the key element, etc. etc., is AIR FLOW! If you DO have the airflow then it is simple to dump in more fuel and = get more power. If you don't have the airflow in the induction system, = then it don't make no never mind how much fuel you pour into it, it = won't produce more power. Clearly, its not a simple matter to get great = airflow for a number of reason mentioned. Tracy has (I think) shown that airflow velocity apparently plays a = major role in producing power. His runners are 1.25 and 1.5" in dia - = so clearly not oversized. This creates higher air velocity in the = runners which in turn can cram more air into the chamber when the port = opens (the momentum effect of the moving air) =20 Now taking the fact that at 6000 rpm and 100% VE a 80 CID rotary will = suck approx 277 CFM of air, so each set of runners flow approx `1/2 *277 = or 138 CFM. Assuming that the air divides between the two runners = proportional to their areas 40% for the primary and 60% for the = secondary. We have .4*138 =3D 52 CFM and 0.6* 138 =3D 82 CFM To find the air velocity in each runner we divide the flow in each = runner by the area of that runner we find that the average velocity of = air in the intake is only on the order of 110 fps or approx 75 mph. = Now most induction theory says you want an intake velocity on the order = of 300 fps, but there of course as always a trade off. If you reduce = the intake diameter in order to achieve 300 fps in the rotary you would = have to reduce the runner dia even more and that starts to cause airflow = restrictions especially at higher rpm. On the other hand, if you = enlarge the diam of the runners much beyond what Mazda used, then the = intake velocity will decrease and could adversely affect the inertia = chamber stuffing effect. At least that is how it appears to me. When I combined my primary and secondary runner, I ensured that the = total area of the single tube did not exceed the combined area of both = primary and secondary tubes in the attempt to keep the airflow velocity = the same as in the Mazda. FWIW Ed=20 ------=_NextPart_000_002D_01C43730.FF7C4A70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
 From: Russell Duffy
Sent: Monday, May 10, 2004 9:33 = PM
Subject: [FlyRotary] injector = relocation=20 predictions?

Greetings,
 
As I = mentioned before,=20 one of the relatively easy options for improvement will be to move the = 4=20 injectors, and keep the current intake.  As they are now, all 4 = injectors=20 are in the TB, which is 30 inches away on the cold side of the=20 engine.  I believe I can mount the two stock primaries back in = the block,=20 and can probably mount the two secondaries in the intake, maybe 2 = inches from=20 the engine.  
 
Here's the = question, do=20 you think this will increase power?  In other words, am I losing = power by=20 having the injectors coating the inside of the long tubing, rather = than=20 efficiently delivering the fuel to the=20 engine?  
 
Thanks,
Rusty = (thinking of=20 draining one fuel tank, and filling it with helium to improve=20 climb)   
 
Rusty, I=20 don't think anyone can answer that question - depends on too many=20 variables.  You would think that even if the fuel coated your = long=20 runners that eventually it ends up in the combustion chamber.  My = (admittedly limited) experience with rotary intakes leads me to = believe that=20 the number one, primary, uno, far outweighing all other factors, = the key=20 element, etc. etc., is AIR FLOW!
 
If you DO=20 have the airflow then it is simple to dump in more fuel and get more=20 power.  If you don't have the airflow in the induction system, = then it=20 don't make no never mind how much fuel you pour into it, it won't = produce more=20 power.  Clearly, its not a simple matter to get great airflow for = a=20 number of reason mentioned.
 
Tracy has=20 (I think) shown that airflow velocity apparently plays a major role in = producing power.  His runners are 1.25 and 1.5" in dia - so = clearly not=20 oversized.  This creates higher air velocity in the runners which = in turn=20 can cram more air into the chamber when the port opens (the momentum = effect of=20 the moving air) 
 
Now taking=20 the fact that at 6000 rpm and 100% VE a 80 CID rotary will suck approx = 277 CFM=20 of air, so each set of runners flow approx `1/2 *277 or 138 CFM.  = Assuming that the air divides between the two runners proportional to = their=20 areas 40% for the primary and 60% for the secondary.  We have = .4*138 =3D 52=20 CFM and 0.6* 138 =3D 82 CFM
 
To find the=20 air velocity in each runner we divide the flow in each runner by the = area of=20 that runner we find that the average velocity of air in the intake is = only on=20 the order of  110 fps or approx 75 mph.  Now most induction = theory=20 says you want an intake velocity on the order of 300 fps, but there of = course=20 as always a trade off.  If you reduce the intake diameter in = order=20 to achieve 300 fps in the rotary you would have to reduce the runner = dia even=20 more and that starts to cause airflow restrictions especially at = higher=20 rpm.  On the other hand, if you enlarge the diam of the runners = much=20 beyond what Mazda used, then the intake velocity will decrease  = and could=20 adversely affect the inertia chamber stuffing effect.  At least = that is=20 how it appears to me.
 
When I=20 combined my primary and secondary runner, I ensured that the total = area of the=20 single tube did not exceed the combined area of both primary and = secondary=20 tubes in the attempt to keep the airflow velocity the same as in the=20 Mazda.
 
 
FWIW
 
Ed=20
 
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