X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-ww0-f42.google.com ([74.125.82.42] verified) by logan.com (CommuniGate Pro SMTP 5.4c2o) with ESMTPS id 4892301 for flyrotary@lancaironline.net; Sat, 05 Mar 2011 19:23:10 -0500 Received-SPF: pass receiver=logan.com; client-ip=74.125.82.42; envelope-from=fluffysheap@gmail.com Received: by wwe15 with SMTP id 15so1430306wwe.1 for ; Sat, 05 Mar 2011 16:22:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=QHZKqbPPk3jFClez/Gfa70L2K8zK77sGWcngHqV4afc=; b=ReXsSV4ubcsFsjHnBheXCHhXNvCH3Z9Jhvr/KLBk0G2k+UdLoU8QNaFFBJa/ryndI9 c0GSsXWTxnK4iqxxSP3U5zfkfrQXQwEzvnsK7PoplV8B0xGQWRlpklS/LMey+CIO1roI Dqd9UuL5A0uueWLRt1Vl1M1vBDBkR/ZYpCX9E= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=jU9dCnWwayt4hDbZYxxEgKsWgx13aNkzQCQJQnlEwVCafh4qpn6veSTzdD6CQWAIjD 82WT/m9iGDEKmXCeDWIPpzqz7ERvc+p7CTYYl4mTXj11vr62cU+Adh0et6Yh2Wcr8G2m 6B6t6aoojdUtm4PKGiwnnCxlreTgySoqMERPU= MIME-Version: 1.0 Received: by 10.227.140.23 with SMTP id g23mr1996152wbu.46.1299370955368; Sat, 05 Mar 2011 16:22:35 -0800 (PST) Received: by 10.227.142.202 with HTTP; Sat, 5 Mar 2011 16:22:35 -0800 (PST) In-Reply-To: References: Date: Sat, 5 Mar 2011 17:22:35 -0700 Message-ID: Subject: Re: [FlyRotary] Re: Knock sensor and indicator From: William Wilson To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0016e6d64db239ea1d049dc5607c --0016e6d64db239ea1d049dc5607c Content-Type: text/plain; charset=ISO-8859-1 Brad Barber wrote: "This time, the compression on the rear rotor was still over 100 psi, however, the compression on the front housing, while still around 80 ps....was only giving me TWO "bounces". Yeah, for any noobs on the list, there must be three "bounces". Also, the chugchuga wosh did not sound "right". DOH! I checked and rechecked. So, one of the front seals seems bent too. No real surprise. " My guess would be that this is not an apex seal. Given your previous center iron problems you may still be having issues in that department, or maybe you have a warped housing that caused your center iron problem (and this problem). The reason I feel this way is that the behavior is different cold and hot, and because it seems to affect only one combustion chamber. Apex seals generally affect two (or all three), and if they're damaged, they don't seal at any temperature. Since it's temperature dependent, it's probably a side sealing problem which is partly sealed at low temperature, but then unseals itself when it heats up and the parts expand. I'd recommend having all your housings checked for true, probably even the front and rear, but especially the rotor and center. Also, pay close attention to the torque when you put it back together, use new bolts and make sure there's no crud in there that could mess up the torque. You know, my father had a block crack on a piston engine when a head bolt didn't fit properly even though everything was torqued correctly - I never heard of something like this on a rotary, but I tend to think both of these problems are related and it probably won't go away until whatever is the cause gets fixed. Kelly Troyer wrote: "I just remembered one other tidbit of info from our rotary guru Lynn.........One of his informative posts on fuel and the effects of octane ratings stated that as you lean the auto fuel that many of us use (87 to 91 octane) that the flame front is slowed and this mimics the effect of lead in fuel" Generally, leaner mixture increases the risk of detonation, regardless of octane or presence of lead. On a naturally aspirated rotary it doesn't usually matter much. I find this page to be an excellent reference for the effects of octane: http://www.turborx7.com/fuel.htm "One other point that I forgot to mention was ignition timing..........It is my understanding that turboed engines should not use excessive timing advance and that the higher the boost the less timing advance is needed (or wise).........As I recall ignition timing as high as 27 + degrees BTDC has/is used for naturally aspirated rotarys" I think the confusion here is between talking about the timing at idle and the timing at high RPM. When you set the timing you are usually setting the idle timing, then the ECU adds a certain amount of advance based on the RPM, temperature, whatever. 10 degrees is probably the idle setting, not the maximum advance, whereas the 27+ is probably the maximum advance (maximum advance in my car is about 35). --0016e6d64db239ea1d049dc5607c Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Brad Barber wrote:
"This time, t= he compression on the rear rotor was still over 100 psi, however, the compr= ession on the front housing, while still around 80 ps....was only giving me= TWO "bounces".=A0 Yeah, for any noobs on the list, there must be= three "bounces".=A0 Also, the chugchuga wosh did not sound "= ;right". DOH!=A0 I checked and rechecked.=A0 So, one of the front seal= s seems bent too.=A0 No real surprise. "

My guess would be that this is not an apex seal.=A0 Given your pr= evious center iron problems you may still be having issues in that departme= nt, or maybe you have a warped housing that caused your center iron problem= (and this problem).

The reason I feel this way is that the behavior is different cold and h= ot, and because it seems to affect only one combustion chamber.=A0 Apex sea= ls generally affect two (or all three), and if they're damaged, they do= n't seal at any temperature.=A0 Since it's temperature dependent, i= t's probably a side sealing problem which is partly sealed at low tempe= rature, but then unseals itself when it heats up and the parts expand.=A0 <= br>
I'd recommend having all your housings checked for true, probably e= ven the front and rear, but especially the rotor and center.=A0 Also, pay c= lose attention to the torque when you put it back together, use new bolts a= nd make sure there's no crud in there that could mess up the torque.=A0= You know, my father had a block crack on a piston engine when a head bolt = didn't fit properly even though everything was torqued correctly - I ne= ver heard of something like this on a rotary, but I tend to think both of t= hese problems are related and it probably won't go away until whatever = is the cause gets fixed.

Kelly Troyer wrote:
"I just r= emembered one other tidbit of info from our rotary guru Lynn.........One of=
his informative posts on fuel and the effects of octane ratings stated = that as you lean
the auto fuel that many of us use (87 to 91 octane) that the flame front is= slowed and
this mimics the effect of lead in fuel"

Ge= nerally, leaner mixture increases the risk of detonation, regardless of oct= ane or presence of lead.=A0 On a naturally aspirated rotary it doesn't = usually matter much.

I find this page to be an excellent reference for the effects of octane= :
http://www.turborx7.com/f= uel.htm

"One other point = that I forgot to mention was ignition timing..........It is my understandin= g
that turboed engines should not use excessive timing advance and that the h= igher the
boost the less timing advance is needed (or wise).........As I= recall ignition timing as high
as 27 + degrees BTDC has/is used for nat= urally aspirated rotarys"

I think the confusion here is between talking about the timing at= idle and the timing at high RPM.=A0 When you set the timing you are usuall= y setting the idle timing, then the ECU adds a certain amount of advance ba= sed on the RPM, temperature, whatever.=A0 10 degrees is probably the idle s= etting, not the maximum advance, whereas the 27+ is probably the maximum ad= vance (maximum advance in my car is about 35).


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