X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-da03.mx.aol.com ([205.188.105.145] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTP id 5559157 for flyrotary@lancaironline.net; Fri, 25 May 2012 02:32:02 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.145; envelope-from=Lehanover@aol.com Received: from mtaomg-db06.r1000.mx.aol.com (mtaomg-db06.r1000.mx.aol.com [172.29.51.204]) by imr-da03.mx.aol.com (8.14.1/8.14.1) with ESMTP id q4P6VOsL023002 for ; Fri, 25 May 2012 02:31:24 -0400 Received: from core-mob004c.r1000.mail.aol.com (core-mob004.r1000.mail.aol.com [172.29.194.205]) by mtaomg-db06.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id 7E75FE000081 for ; Fri, 25 May 2012 02:31:24 -0400 (EDT) From: Lehanover@aol.com Message-ID: <86553.66ce40f5.3cf0813b@aol.com> Date: Fri, 25 May 2012 02:31:23 -0400 (EDT) Subject: Re: [FlyRotary] Idle MAP To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_86553.66ce40f5.3cf0813b_boundary" X-Mailer: AOL 9.6 sub 5004 X-Originating-IP: [173.88.30.23] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20110426; t=1337927484; bh=zkL1MGm6X4YW0lRRNkod4jWK7mwWM79xy9dkeba2kmA=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=GAFrSx4z16zkIibHWkzejPcEKkZEdv6mqK1Y8dpL/naDtmKOJSyI2vUO9Y7Kw6mGB XfJawS6tiDYWIP9NNJ0kkFnSZXFXBqITG5Ue+oESJXNJ4sGrrkoDPuTjAmZh7BFuZ9 WEGftW4tNFtCNmC0nPnLygrKganbs7UCm7RbLOiU= X-AOL-SCOLL-SCORE: 0:2:402919392:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d33cc4fbf273c6378 --part1_86553.66ce40f5.3cf0813b_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 5/25/2012 12:42:43 A.M. Eastern Daylight Time, echristley@att.net writes: I'm showing a MAP of around 55kPa, about half of sea level static, with an idle of 1400 and an AFR of 18:1. I'd like to drop the idle further. I had it closer to 900 before, but the idle is now rather rough, which I'm attributing to the ultra lean mixture. Is this the lowest MAP I can reasonably expect? Or is there a reasonable expectation of a manifold leak? A garden hose on the suspect manifold junctions will show up a leak, as the engine runs better with water blocking part of that leak. But don't panic yet. Observations seem to be normal so far. In closed throttle situations where little air is available you see timing have a new power over performance. Lean mixtures burn very slowly and you may find happiness with more advance just at idle. Over-lean idle tends to hunt a bit more than a rich idle. Also the load from the prop drops off rapidly with RPM. The RX-8 maps up to 44 degrees on high RPM closed throttle, like going down hill, or slowing from speed. Get some idle RPM data from another user. There is a too slow number to be avoided. While the rotary does not have reversals like a piston engine it does have two major torque pulses per revolution. With little flywheel effect and low RPM it can shake the daylights out of a gear box. The racer has only a 5 1/4" Tilton button clutch bolted on over a flex plate. If the idle is too slow it shakes the transmission so hard you can hear it a block away. The late Mr. Graham stripped off the teeth in his gear box, fortunately on the ground. Notice that Mazda rotaries have flywheels that look like Caterpillar diesel pieces. The racer idles at 2,200 RPM. Minimum useful RPM is about 7,800. Had a bit of a flood here a few weeks back. Had to run back from Florida early. Racer is OK. The spare engine was on 4X4 blocks on the floor and now needs a rebuild to check for water (and mud) damage. Lynn E. Hanover BTW, Lynn, now that I have a fairly stable idle, I'm looking closer at the timing. It looks as if the RPM jumps from 1450 to 1250 as the timing drops from 21 to 20. There are many places in the graph where I can watch the RPM following the ADV up and down, which tells me that I still have a lot of power left hiding in the timing tables. (The RPM rises when the timing does.) I also made a point of noting the EGT gauge reading. I stayed down around 1200*, for the most part, but did have an excursion up to 1600* with the throttle 70% open. The MAP read 93kPa. The AFR was swinging between 15 and 14.5. I've since shifted the numbers to avoid doing that, but it will have to wait to get tested. Had surgery to repair a torn meniscus on my knee today. -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html --part1_86553.66ce40f5.3cf0813b_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
 
 
In a message dated 5/25/2012 12:42:43 A.M. Eastern Daylight Time,=20 echristley@att.net writes:
= I'm=20 showing a MAP of around 55kPa, about half of sea level static, with an id= le of=20 1400 and an AFR of 18:1.

I'd like to drop the idle further.  = I had=20 it closer to 900 before, but the idle is now rather rough, which I'm=20 attributing to the ultra lean mixture.  Is this the lowest MAP I can= =20 reasonably expect?  Or is there a reasonable expectation of a manifo= ld=20 leak?
A garden hose on the suspect manifold junctions will show up a leak, a= s the=20 engine runs better with water blocking part of that leak. But don't panic y= et.=20 Observations seem to be normal so far. In closed throttle situations where= =20 little air is available you see timing have a new power over performance. L= ean=20 mixtures burn very slowly and you may find happiness with more advance just= at=20 idle. Over-lean idle tends to hunt a bit more than a rich idle. Also the lo= ad=20 from the prop drops off rapidly with RPM.
 
The RX-8 maps up to 44 degrees on high RPM closed throttle, like going= down=20 hill, or slowing from speed.
 
Get some idle RPM data from another user. There is a too slow number t= o be=20 avoided. While the rotary does not have reversals like a piston engine it d= oes=20 have two major torque pulses per revolution.
 
With little flywheel effect and low RPM it can shake the daylights out= of a=20 gear box. The racer has only a 5 1/4" Tilton button clutch bolted on o= ver a=20 flex plate. If the idle is too slow it shakes the transmission so hard you = can=20 hear it a block away. The late Mr. Graham stripped off the teeth in his gea= r=20 box, fortunately on the ground. Notice that Mazda
rotaries have flywheels that look like Caterpillar diesel=20 pieces. 
 
The racer idles at 2,200 RPM. Minimum useful RPM is about 7,800.
 
Had a bit of a flood here a few weeks back. Had to run back from Flori= da=20 early. Racer is OK. The spare engine was on 4X4 blocks on the floor and now= =20 needs a rebuild to check for water (and mud) damage.
 
Lynn E. Hanover
=

BTW, Lynn,  now that I have a fairly stable idl= e, I'm=20 looking closer at the timing.  It looks as if the RPM jumps from 145= 0 to=20 1250 as the timing drops from 21 to 20.  There are many places in th= e=20 graph where I can watch the RPM following the ADV up and down, which tell= s me=20 that I still have a lot of power left hiding in the timing tables. (The R= PM=20 rises when the timing does.)

I also made a point of noting the EGT= =20 gauge reading.  I stayed down around 1200*, for the most part, but d= id=20 have an excursion up to 1600* with the throttle 70% open.  The MAP r= ead=20 93kPa. The AFR was swinging between 15 and 14.5.   I've since= =20 shifted the numbers to avoid doing that, but it will have to wait to get= =20 tested.  Had surgery to repair a torn meniscus on my knee=20 today.
--
Homepage:  http://www.flyrotary.com/
Archive and= =20 UnSub:  =20 http://mail.lancaironline.net:81/lists/flyrotary/List.html
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