X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail17.syd.optusnet.com.au ([211.29.132.198] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTPS id 2271400 for flyrotary@lancaironline.net; Sat, 18 Aug 2007 20:24:31 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.132.198; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-119-28.dsl.nsw.optusnet.com.au [211.31.119.28]) by mail17.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id l7J0Ngdq011363 for ; Sun, 19 Aug 2007 10:23:45 +1000 Message-ID: <002a01c7e1f7$35b3dc60$1c771fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Power! More Power, Scotty! was [FlyRotary] Re: Air/fuel flow Date: Sun, 19 Aug 2007 10:23:43 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0027_01C7E24B.04F3F570" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Antivirus: avast! (VPS 0657-0, 12/12/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_0027_01C7E24B.04F3F570 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Richard, Your doing physically what I'm trying to do predict on paper. What is = the Max CFM as suggested by Mikuni 38mm? I had a look at the Edelbrock Motorcycle site and they indicate a 48mm = carb for 120+HP. A lot of difference between those two figures. George ( down under) Nevertheless, Lynn,s comments safed my day. I was trying to tune the single rotor over the past few weeks. Using a = 38mm Mikuni round slide, I got it to idle clean up from 1600rpm. = Transition into midrange and up to WOT is no problem. Trying to get the = mixture richer at WOT, I did not get the responce to enlarging the main = jet I expected. The mixture stayed lean, indicated by high EGT and white = plug insulators, to some extend suported by the O2 reading. The air flow = rate at 6000 rpm is almost double of what Mikuni says is max. I started = wondering. Now Lynn said " carbs get leaner to the top of their RPM ranges" . = There may be the answer to my problem: bigger carb! Richard Sohn N2071U ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Saturday, August 18, 2007 8:22 AM Subject: [FlyRotary] Power! More Power, Scotty! was [FlyRotary] Re: = Air/fuel flow 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. -------------------------------------------------------------------------= --- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.476 / Virus Database: 269.11.19/953 - Release Date: = 8/14/2007 5:19 PM -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.484 / Virus Database: 269.12.0/959 - Release Date: = 17/08/2007 5:43 PM ------=_NextPart_000_0027_01C7E24B.04F3F570 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Richard,
Your doing physically what I'm trying to do predict on paper. What = is the=20 Max CFM as suggested by Mikuni 38mm?
I had a look at the Edelbrock Motorcycle site and they indicate a = 48mm carb=20 for 120+HP. A lot of difference between those two figures.
George ( down under)
Nevertheless, Lynn,s comments safed my day.
 
I was trying to tune the single rotor over the past few weeks. = Using a=20 38mm Mikuni round slide, I got it to idle clean up from 1600rpm. = Transition=20 into midrange and up to WOT is no problem. Trying to get the = mixture=20 richer at WOT, I did not get the responce to enlarging the = main jet=20 I expected. The mixture stayed lean, indicated by high EGT and white = plug=20 insulators, to some extend suported by the O2 reading. The air flow = rate at=20 6000 rpm is almost double of what Mikuni says is max. I started=20 wondering.
Now Lynn said " carbs get leaner to the top of their RPM ranges" = . There=20 may be the answer to my problem: bigger carb!
 
Richard Sohn
N2071U
----- Original Message -----
From:=20 Ed Anderson
To: Rotary motors in = aircraft=20
Sent: Saturday, August 18, = 2007 8:22=20 AM
Subject: [FlyRotary] Power! = More Power,=20 Scotty! was [FlyRotary] Re: Air/fuel flow

Lynn's summation says it all (if it ever is all = said=20 {:>)).
 
The bottom line is that atmospheric oxygen to = support=20 combustion is the limitation in making power.  You can always = add more=20 fuel if you could just get more air/oxygen  into the combustion = 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=20 to some sort of forced induction or to an oxidizer like nitrous = oxide to=20 provide 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=20 things done to improve it at one rpm may well hurt VE at another = rpm. =20 So pick your power band and tune your induction system=20 accordingly.
 
Ed
 
 
----- Original Message ----- =
From:=20 Lehanover@aol.com
To: Rotary motors in = aircraft=20
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=20 - if you happened to have some info on that.
 
Everyday cars have 450' per sec and race cars 125' per = second,(=20 suggested on a carb site) Ed's calculations used 176' = per=20 second which indicated a bigger inlet diameter. I was thinking = about 300=20 to 350' 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=20 too low to help us much but the car designers use this and stretch = it=20 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=20 nice Rumppp...Rumppp...Rumppp. Breathing is very good = compared to a=20 piston engine, and runner diameter is small for any HP output. The = stock=20 intake manifold gasket in my engines (Daryl Drummond) is barely = enlarged=20 at all. The new engine may have more than two such RPM.
 
Porting extends the intake open time and makes for a more = turbine=20 like flow. Even a street port can nearly double the stock HP, and = that=20 would require nearly double the stock airflow. Down low the race = or even=20 street ported engine has little advantage over the stock engine. = For any=20 RPM the air flow determines the HP output, so where (RPM) you are=20 interested in output there will need to be dramatically improved=20 airflow. 
 
So generally, the displacement times the RPM minus some = percentage=20 for inlet restriction based on TP size or carb choke size and or = runner=20 length and 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=20 engine will have very much more power than a stock engine at = the same=20 RPM, indicating a much higher than stock (CFM) air flow. Maybe not = over=20 100% VE but much closer to that number than the stock engine. =
 
There is no cheating possible here. So if your example engine = is=20 compared to any other engine with more power at the same RPM. The = higher=20 power output requires very much more airflow, not less.
 
Something is amiss Watson.........I can feel it!
 
Lynn E. Hanover   



Get a sneak peek of the all-new AOL.com.

No virus found in this incoming message.
Checked by AVG = Free=20 Edition.
Version: 7.5.476 / Virus Database: 269.11.19/953 - = Release=20 Date: 8/14/2007 5:19 PM

No virus found in this incoming message.
Checked by AVG Free = Edition.
Version: 7.5.484 / Virus Database: 269.12.0/959 - Release = Date:=20 17/08/2007 5:43 PM
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