X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: <13brv3@bellsouth.net> Received: from imf20aec.mail.bellsouth.net ([205.152.59.68] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 912165 for flyrotary@lancaironline.net; Sat, 23 Apr 2005 11:03:28 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.68; envelope-from=13brv3@bellsouth.net Received: from rd ([65.6.194.9]) by imf20aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20050423150244.QHUY1992.imf20aec.mail.bellsouth.net@rd> for ; Sat, 23 Apr 2005 11:02:44 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] rotor and seal wear was Re: All Parts have arrived, Whew! Date: Sat, 23 Apr 2005 10:02:44 -0500 Message-ID: <000001c54815$810504b0$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C547EB.982EFCB0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C547EB.982EFCB0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable What I seem to have missed is the compelling reason why we can't simply mill the slots out to 3 mm, install new seals and continue the march. I know Tracy's "new formulation" seals only come in 2 mm, but I speculate that would be pretty easy to change given the current rash of wallowed out 2 mm slots and the potential market for 3mm versions.=20 =20 Hi Jim, =20 First, Tracy's/Bruce's new seals are certainly available in 3mm, and at = the same price of the 2mm seals. From what I've understood (or thought I = did), the 2mm seals actually "seal" better than the 3mm seals. For a street engine, (idle, emissions, etc) that's clearly better, or Mazda wouldn't = have changed to them in 86 (I think). I don't think there's anything really wrong with running 3mm seals if you want to. =20 I'm more interested in what causes the slots to open up. If Bruce is correct, and they're just bent outward, then I guess the force of = combustion is causing this??? Imagine when the plug fires, there's a huge force created. That force would push outward on the two apex seals that = border that particular rotor face. When the next face fires, the seal that was previously forced backwards, is now forced forward. I can imagine that = this back and forth hammering would tend to open up the slot. I guess the = real question is what causes this to be worse in some engines than others. = The obvious answer would be that it's worse in engines that produce lots of power, for long periods of time. =20 =20 Lynn, Leon, do you see this in racing engines? =20 If all the above is true, then I can also see far more stress being put = on the seals as the slot widens. Imagine the seals slapping back and forth rapidly. What happens if a tiny bit of carbon, sand, etc manages to get = in the apex slot, and then the seal is slammed into it. Wouldn't that = offer the opportunity to snap a brittle seal? =20 =20 To add to this SWAGing, I would also like to mention that Ed is not = alone with his observation of excessive wear on Hurley seals. My engine = probably had 80 total hours on it before the oil cooler incident, and there's a remarkable amount of wear on the sides of my seals. These were in new rotors, and the apex slots are still at new specs, so it wasn't caused = by out of spec slots. Leon may have a point about dust in this case, since = I didn't run with a filter, and half of my running time was on the ground. = =20 =20 At some point, I'm going to measure one of the old Hurley seals to see = just how much of a groove was worn in them. Just from looking at them, I can tell that it's much more wear than the Mazda seals in the old (??? = miles) engine in the box in the garage. Suffice to say that I'm happy that I = have the new seals in my current engine. =20 =20 Cheers, Rusty (firewire hard drives biting the dust left and right...) ------=_NextPart_000_0001_01C547EB.982EFCB0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

What I seem to have missed is the compelling = reason
why we=20 can't simply mill the slots out to 3 mm, install new seals = and
continue the=20 march.  I know Tracy's "new formulation" seals only come in
2 = mm, but I=20 speculate that would be pretty easy to change given the
current rash = of=20 wallowed out 2 mm slots and the potential market for=20 3mm
versions. 

 
Hi=20 Jim,
 
First, = Tracy's/Bruce's=20 new seals are certainly available in 3mm, and at the same price of the = 2mm=20 seals.   From what I've understood (or thought I did), = the 2mm=20 seals actually "seal" better than the 3mm seals.  For a street = engine,=20 (idle, emissions, etc) that's clearly better, or Mazda wouldn't have = changed to=20 them in 86 (I think).  I don't think there's anything really wrong = with=20 running 3mm seals if you want to.
 
I'm more = interested in=20 what causes the slots to open up.  If Bruce is correct, = and=20 they're just bent outward, then I guess the force of combustion is = causing=20 this???  Imagine when the plug fires, there's a huge = force=20 created.  That force would push outward on the two apex seals that = border=20 that particular rotor face.  When the next face fires, the seal = that was=20 previously forced backwards, is now forced forward.  I can imagine = that=20 this back and forth hammering would tend to open up the = slot.   I=20 guess the real question is what causes this to be worse in some engines = than=20 others.  The obvious answer would be that it's worse in engines = that=20 produce lots of power, for long periods of time.  =
 
Lynn, Leon, do you see this in = racing=20 engines?
 
If all = the above is=20 true, then I can also see far more stress being put on the seals as the = slot=20 widens.  Imagine the seals slapping back and forth rapidly.  = What=20 happens if a tiny bit of carbon, sand, etc manages to get in the=20 apex slot, and then the seal is slammed into it.  Wouldn't=20 that offer the opportunity to snap a brittle=20 seal?  
 
To add = to this SWAGing,=20 I would also like to mention that Ed is not alone with his = observation of=20 excessive wear on Hurley seals.  My engine probably had 80 total = hours on=20 it before the oil cooler incident, and there's a remarkable amount = of wear=20 on the sides of my seals.  These were in new rotors, and = the apex=20 slots are still at new specs, so it wasn't caused by out of spec = slots. =20 Leon may have a point about dust in this case, since I didn't run = with a=20 filter, and half of my running time was on the=20 ground.  
 
At some = point,=20 I'm going to measure one of the old Hurley seals to see just how = much of=20 a groove was worn in them.  Just from looking at them, I = can tell=20 that it's much more wear than the Mazda seals in the old (??? = miles) engine=20 in the box in the garage.  Suffice to say that I'm happy = that I=20 have the new seals in my current engine.    =20
 
Cheers,
Rusty = (firewire hard=20 drives biting the dust left and right...)



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