X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from email2k3.itlnet.net ([64.19.112.12] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 912207 for flyrotary@lancaironline.net; Sat, 23 Apr 2005 11:19:55 -0400 Received-SPF: none receiver=logan.com; client-ip=64.19.112.12; envelope-from=jwvoto@itlnet.net Received: from rav.itlnet.net (unverified [192.168.10.149]) by itlnet.net (Rockliffe SMTPRA 6.1.17) with SMTP id for ; Sat, 23 Apr 2005 10:19:11 -0500 Received: from JWVOTO (unverified [64.19.115.48]) by itlnet.net (Rockliffe SMTPRA 6.1.17) with SMTP id for ; Sat, 23 Apr 2005 10:19:09 -0500 Message-ID: <005801c54818$02ae00a0$0100007f@JWVOTO> From: "Wendell Voto" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: rotor and seal wear was Re: All Parts have arrived, Whew! Date: Sat, 23 Apr 2005 10:19:57 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0055_01C547EE.005FE400" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 This is a multi-part message in MIME format. ------=_NextPart_000_0055_01C547EE.005FE400 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageFWIW, looks to me that the distance from the rotor to the housing = causes more or less bending force on the seals. If the distance is = large, then more side force is exerted on the seal and stressing it to = the breaking point. Since Tracy has a high time engine - so far with no = seal problem and is not babying his engine, could this be the reason = some are getting more seal side wear than others? How can the rotor to = housing gap be accurately measured? How much does it change with = temperature? Wendell! 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 Hi Jim, 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. 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 Lynn, Leon, do you see this in racing engines? 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 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 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 Cheers, Rusty (firewire hard drives biting the dust left and right...) ------=_NextPart_000_0055_01C547EE.005FE400 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
FWIW, looks to me that the distance from the = rotor to=20 the housing causes more or less bending force on the seals.  If the = distance is large, then more side force is exerted on the seal and = stressing it=20 to the breaking point. Since Tracy has a high time engine - so far with = no seal=20 problem and is not babying his engine, could this be the reason some are = getting=20 more seal side wear than others?  How can the rotor to housing gap = be=20 accurately measured? How much does it change with = temperature?
Wendell!

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=20 I 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=20 to them in 86 (I think).  I don't think there's anything really = wrong=20 with 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=20 SWAGing, I would also like to mention that Ed is not alone with = his=20 observation of excessive wear on Hurley seals.  My engine = probably had 80=20 total hours on it before the oil cooler incident, and there's a = remarkable=20 amount of wear on the sides of my seals.  These were in new = rotors,=20 and the apex slots are still at new specs, so it wasn't caused by = out of=20 spec slots.  Leon may have a point about dust in this case, = since I=20 didn't run with a 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=20 tell that it's much more wear than the Mazda seals in the old = (??? miles)=20 engine in the box in the garage.  Suffice to say that = I'm happy=20 that I 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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