X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-01.southeast.rr.com ([24.25.9.100] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2270573 for flyrotary@lancaironline.net; Sat, 18 Aug 2007 09:21:49 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-103-061.carolina.res.rr.com [24.74.103.61]) by ms-smtp-01.southeast.rr.com (8.13.6/8.13.6) with SMTP id l7IDL2Pk024889 for ; Sat, 18 Aug 2007 09:21:02 -0400 (EDT) Message-ID: <000901c7e19a$d01c7e90$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Power! More Power, Scotty! was [FlyRotary] Re: Air/fuel flow Date: Sat, 18 Aug 2007 09:22:23 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01C7E179.48B2AC70" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0006_01C7E179.48B2AC70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Lynn's summation says it all (if it ever is all said {:>)). The bottom line is that atmospheric oxygen to support combustion is the = limitation in making power. You can always add more fuel if you could = just get more air/oxygen into the combustion chamber. Using atmospheric pressure alone there is only so much pressure to force = air (approx 20% oxygen) into the combustion chamber. Some combination = of tuning can improve on chamber stuffing over atmospheric pressure = alone, but I think even here you are only talking about 105-110% VE. To = really increase power beyond this point you either need to go to some = sort of forced induction or to an oxidizer like nitrous oxide to provide = more oxygen to burn more fuel to made more power. But, other than that - volumetric flow (CFM) says it all. Anything done = to improve it aids power, but unfortunately, the things done to improve = it at one rpm may well hurt VE at another rpm. So pick your power band = and tune your induction system accordingly. Ed ----- Original Message -----=20 From: Lehanover@aol.com=20 To: Rotary motors in aircraft=20 Sent: Saturday, August 18, 2007 8:37 AM Subject: [FlyRotary] Re: Air/fuel flow In a message dated 8/18/2007 3:13:31 A.M. Eastern Daylight Time, = lendich@optusnet.com.au writes: Lynn, The question was on inlet velocity for a Mazda rotary at 7,500 rpm - = if you happened to have some info on that. Everyday cars have 450' per sec and race cars 125' per second,( = suggested on a carb site) Ed's calculations used 176' per second which = indicated a bigger inlet diameter. I was thinking about 300 to 350' per = second would more like it, but I have no real hard data! Well then let me speculate.=20 The engines have two RPM where they wander above 100% VE. These are = too low to help us much but the car designers use this and stretch it = out a bit looking at the pipe organ intakes. Just off idle and about 2,000 RPM. This confuses the idle and = transition circuits in the Weber and you get a nice = Rumppp...Rumppp...Rumppp. Breathing is very good compared to a piston = engine, and runner diameter is small for any HP output. The stock intake = manifold gasket in my engines (Daryl Drummond) is barely enlarged at = all. The new engine may have more than two such RPM. Porting extends the intake open time and makes for a more turbine like = flow. Even a street port can nearly double the stock HP, and that would = require nearly double the stock airflow. Down low the race or even = street ported engine has little advantage over the stock engine. For any = RPM the air flow determines the HP output, so where (RPM) you are = interested in output there will need to be dramatically improved = airflow.=20 So generally, the displacement times the RPM minus some percentage for = inlet restriction based on TP size or carb choke size and or runner = length and diameter will be the stock situation and one CFM value. And in a modified intake system with longer runners of slightly more = diameter which will favor the same RPM as the stock example engine will = have very much more power than a stock engine at the same RPM, = indicating a much higher than stock (CFM) air flow. Maybe not over 100% = VE but much closer to that number than the stock engine.=20 There is no cheating possible here. So if your example engine is = compared to any other engine with more power at the same RPM. The higher = power output requires very much more airflow, not less.=20 Something is amiss Watson.........I can feel it! Lynn E. Hanover =20 -------------------------------------------------------------------------= ----- Get a sneak peek of the all-new AOL.com. ------=_NextPart_000_0006_01C7E179.48B2AC70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Lynn's summation says it all (if it ever is all said = {:>)).
 
The bottom line is that atmospheric oxygen to = support=20 combustion is the limitation in making power.  You can always add = more fuel=20 if you could just get more air/oxygen  into the combustion=20 chamber.
 
Using atmospheric pressure alone there is only so = much=20 pressure to force air (approx 20% oxygen) into the combustion = chamber. =20 Some combination of tuning can improve on chamber stuffing over = atmospheric=20 pressure alone, but I think even here you are only talking about = 105-110%=20 VE.  To really increase power beyond this point you either need to = go to=20 some sort of forced induction or to an oxidizer like nitrous oxide to = provide=20 more oxygen to burn more fuel to made more power.
 
But, other than that - volumetric flow (CFM) = says it=20 all.  Anything done to improve it aids power, but unfortunately, = the things=20 done to improve it at one rpm may well hurt VE at another rpm.  So = pick=20 your power band and tune your induction system accordingly.
 
Ed
 
 
----- Original Message -----
From:=20 Lehanover@aol.com
Sent: Saturday, August 18, 2007 = 8:37=20 AM
Subject: [FlyRotary] Re: = Air/fuel=20 flow

In a message dated 8/18/2007 3:13:31 A.M. Eastern Daylight Time, = lendich@optusnet.com.au=20 writes:
Lynn,
The question was on inlet velocity for a Mazda rotary at 7,500 = rpm - if=20 you happened to have some info on that.
 
Everyday cars have 450' per sec and race cars 125' per second,( = suggested on a carb site) Ed's calculations used 176' per = second=20 which indicated a bigger inlet diameter. I was thinking about 300 to = 350'=20 per second would more like it, but I have no real hard=20 data!
Well then let me speculate.
 
The engines have two RPM where they wander above 100% VE. These = are too=20 low to help us much but the car designers use this and stretch it = out a=20 bit looking at the pipe organ intakes.
 
Just off idle and about 2,000 RPM. This confuses the idle and = transition=20 circuits in the Weber and you get a = nice Rumppp...Rumppp...Rumppp.=20 Breathing is very good compared to a piston engine, and runner = diameter is=20 small for any HP output. The stock intake manifold gasket in my = engines (Daryl=20 Drummond) is barely enlarged at all. The new engine may have more than = two=20 such RPM.
 
Porting extends the intake open time and makes for a more turbine = like=20 flow. Even a street port can nearly double the stock HP, and that = would=20 require nearly double the stock airflow. Down low the race or even = street=20 ported engine has little advantage over the stock engine. For any RPM = the air=20 flow determines the HP output, so where (RPM) you are interested in = output=20 there will need to be dramatically improved airflow. 
 
So generally, the displacement times the RPM minus some = percentage for=20 inlet restriction based on TP size or carb choke size and or runner = length and=20 diameter will be the stock situation and one CFM value.
 
And in a modified intake system with longer runners of slightly = more=20 diameter which will favor the same RPM as the stock example = engine will=20 have very much more power than a stock engine at the same RPM, = indicating a=20 much higher than stock (CFM) air flow. Maybe not over 100% VE but much = closer=20 to that number than the stock engine.
 
There is no cheating possible here. So if your example engine is = compared=20 to any other engine with more power at the same RPM. The higher power = output=20 requires very much more airflow, not less.
 
Something is amiss Watson.........I can feel it!
 
Lynn E. Hanover   



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