X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from gv-out-0910.google.com ([216.239.58.191] verified) by logan.com (CommuniGate Pro SMTP 5.2.4) with ESMTP id 2993925 for flyrotary@lancaironline.net; Fri, 27 Jun 2008 10:01:09 -0400 Received-SPF: pass receiver=logan.com; client-ip=216.239.58.191; envelope-from=lehanover@gmail.com Received: by gv-out-0910.google.com with SMTP id n8so81984gve.13 for ; Fri, 27 Jun 2008 07:00:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:mime-version:content-type; bh=QiwHF1pkof93nIfAox2cpqJv+6Zguw31Z1I7ZshQLFg=; b=D4FLxNMuDrSs+vM8PiIPqPkfQqA9CbfaD9M6zkbK/9i6739znSosJIatvsdWTvqXvC h+azh4/0x7ek1Jb1roHsoRwXDe8bW9SGyImqAWltl3ignrbryfbOZRKQg5yDFcdcGsov WsZejjaGh+9C6etpvYJyXHqYyLNPtu8SlH0a0= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:mime-version:content-type; b=uwHo+NUeBdRFttg4YydJBYeppq3TMV6ITh2d4UIedtgIVx3J86b2cPTyZUDQNAjimd rDWCP2OSkRnAb7N03zXtcjLP7dSQ88qC4RS70gsme4DdB7LUH41uRKnB3i1NX2SkUYtV wYVBxb4mFT2VXw8bngPLS7kKPTSqqhRo6S8Mc= Received: by 10.78.143.19 with SMTP id q19mr438595hud.114.1214575228184; Fri, 27 Jun 2008 07:00:28 -0700 (PDT) Received: by 10.78.164.13 with HTTP; Fri, 27 Jun 2008 07:00:28 -0700 (PDT) Message-ID: <1ab24f410806270700o4a2889cexe76607f76d68a0ad@mail.gmail.com> Date: Fri, 27 Jun 2008 10:00:28 -0400 From: "Lynn Hanover" To: flyrotary@lancaironline.net Subject: Lean of Peak operation. MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_7905_15824054.1214575228167" ------=_Part_7905_15824054.1214575228167 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline I'm finding that at about 100F LOP I sense that the engine is starting to not like it =96 like it doesn't seem to be entirely smooth; maybe an occasional miss here and there. Am I right that some of you guys run as much as 200 LOP; or is it my imagination =96 in both cases. Would timing setting have much of anything to do with running LOP? Just past by the 100 hr mark on the engine near the end of a 500 mile trip on Monday. I plan to leave next Monday on a round trip of over 2000 nm ove= r the following week. That'll rack up a few hours. Al In olden times, if your engineer didn't dial up well lean of peak on all 4 engines you would be landing in the water well short of Gatwick. Now, instead of thousands of pilots knowing about lean of peak operation, w= e have that number badmouthing LOP because they saw in the Lycoming manual that it hurts the engine. Why this institutional ignorance would be carried forward is a mystery to me. George Braley in Ada Oklahoma has run the flat engines for thousands of hours on the dyno to see for sure what is what. He sells kits of injectors for flat engines using the Bendix dribble injection system, so that each cylinder can be tuned to hit peak EGT at the same time while leaning. You need EGT probes on each cylinder of course. A recording system of some sort is a big help. So you install the GAMMI injectors and run the test at several altitudes an= d send in the results with however many GAMMIs need changed. He sends back th= e leaner or richer injectors for each cylinder, and you test again. Once you finish, you may have 6 different flow rates in 6 cylinders. Since the fuel delivery is based on airflow and a look at the itake system shows = 6 differing lengths of tubing, 6 different injectors seems like the right answere. Once you have this finished, you can hammer from Columbus Ohio to Zephyrhills (the place to park when going to Sun&Fun) at the top of the yellow arc and at 12 GPH. In a 1960 M model with a fresh 550 and super simitar 3 blade prop. Engine is smooth as silk. Low cylinder head temps, lo= w oil temps, no metal in the reports. It should work just fine in a rotary, so long as fuel flow in both housings is about the same. The troubled engine feel is when one housing is performing less well than the other. So when leaning one housing has peaked before or after the other, or has reached well lean of peak before the other. The leaner mixture is a bit harder to light, and burns a bit slower than a richer mixture. This is a benifit in big piston engines as it replicates a higher octane fuel, resisting detonation along the way. So a slight increase in ignition advance might be a help. Also the balance of the injectors may be off slightly, and there are companies who can balance stock injectors, or just test and tag a bunch of them so you can pi= c two pair that are very close in performance. Nobody races a rotary without a multi spark ignition system. The performanc= e you are trying to achieve is at the upper edge of Kettering system performance. So, timing adjustments and split changes might be helpful. Fresh plugs gapped tight. Throttle wide open. Lynn E. Hanover ------=_Part_7905_15824054.1214575228167 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline

I'm findin= g that at about 100F LOP I sense that the engine is starting to not like it= =96 like it doesn't seem to be entirely smooth; maybe an occasional miss h= ere and there.  Am I right that some of you guys run as much as 200 LO= P; or is it my imagination =96 in both cases.

 

Would timi= ng setting have much of anything to do with running LOP?

 

Just past = by the 100 hr mark on the engine near the end of a 500 mile trip on Monday.=  I plan to leave next Monday on a round trip of over 2000 nm over the= following week.  That'll rack up a few hours. 

Al
<= /font> 
<= /font> 
<= /font> 
In olden= times, if your engineer didn't dial up well lean of peak on all 4 engi= nes
you woul= d be landing in the water well short of Gatwick.
<= /font> 
Now, ins= tead of thousands of pilots knowing about lean of peak operation, we have t= hat number badmouthing LOP because they saw in the Lycoming manual that it = hurts the engine. Why this institutional ignorance would be carried forward= is a mystery to me.
<= /font> 
<= /font> 
George B= raley in Ada Oklahoma has run the flat engines for thousands of hours on th= e dyno to see for sure what is what. He sells kits of injectors for flat en= gines using the Bendix dribble injection system, so that each cylinder can = be tuned to hit peak EGT at the same time while leaning. You need EGT probe= s on each cylinder of course. A recording system of some sort is a big help= .
<= /font> 
So you i= nstall the GAMMI injectors and run the test at several altitudes and send i= n the results with however many GAMMIs need changed. He sends back the lean= er or richer injectors for each cylinder, and you test again.
<= /font> 
Once you= finish, you may have 6 different flow rates in 6 cylinders. Since the fuel= delivery is based on airflow and a look at the itake system shows 6 differ= ing lengths of tubing, 6 different injectors seems like the right answere. =
<= /font> 
Once you= have this finished, you can hammer from Columbus Ohio to Zephyrhills (the = place to park when going to Sun&Fun) at the top of the yellow arc and a= t 12 GPH. In a 1960 M model with a fresh 550 and super simitar 3 blade prop= . Engine is smooth as silk. Low cylinder head temps, low oil temps, no meta= l in the reports. 
<= /font> 
It shoul= d work just fine in a rotary, so long as fuel flow in both housings is abou= t the same. The troubled engine feel is when one housing is performing less= well than the other. So when leaning one housing has peaked before or afte= r the other, or has reached well lean of peak before the other.
<= /font> 
The lean= er mixture is a bit harder to light, and burns a bit slower than a richer m= ixture. This is a benifit in big piston engines as it replicates a higher o= ctane fuel, resisting detonation along the way. 
<= /font> 
<= /font> 
So a sli= ght increase in ignition advance might be a help. Also the balance of the i= njectors may be off slightly, and there are companies who can balance stock= injectors, or just test and tag a bunch of them so you can pic two pair th= at are very close in performance. 
<= /font> 
Nobody r= aces a rotary without a multi spark ignition system. The performance you ar= e trying to achieve is at the upper edge of Kettering system performance. S= o, timing adjustments and split changes might be helpful. 
<= /font> 
Fresh pl= ugs gapped tight. Throttle wide open.
<= /font> 
Lynn E. = Hanover
<= /font> 
 
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