X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.2.0) with ESMTP id 2713728 for flyrotary@lancaironline.net; Sun, 03 Feb 2008 17:23:58 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([75.191.190.141]) by cdptpa-omta03.mail.rr.com with SMTP id <20080203222319.WXJN9845.cdptpa-omta03.mail.rr.com@edward2> for ; Sun, 3 Feb 2008 22:23:19 +0000 Message-ID: <002401c866b3$68825450$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" Subject: Fw: [FlyRotary] How to tell: High compression rotors Date: Sun, 3 Feb 2008 17:23:31 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 Sorry, my second sentence should read ...." If that is also true of the 20B...." instead of ..."..also true of the 13B". Ed ----- Original Message ----- From: "Ed Anderson" To: "Rotary motors in aircraft" Sent: Sunday, February 03, 2008 5:15 PM Subject: [FlyRotary] How to tell: High compression rotors > Bob, the compression for the turbo rotors on some models of the 13B were > as low as around 8.4:1. If that is also true of the 13B, then my opinion > is you will see a considerable improvement in power over the low > compression rotors. I went from the 9.4 to the 9.7:1 rotor on my two > rotor and liked the results. I know that small a difference in > compression should not translate into a terrific power increase, but it > seemed make a noticeable difference. Now the challenge is getting the > 9:7:1 - there are not many used ones out there and those that are can be > very worn. Make certain you check the apex seal slot wear measurements > before you stick any in your engine (actually all of its seal slots should > be checked) if using used ones. If apex seal slot wears past the limit > and if you are using the somewhat brittle stock apex seals, they will > break - don't ask me how I know. > > > One thing make certain you are getting 9:7:1 rotors. If you place a > straight edge across the compression dish and then measure vertically down > until you hit the top of the rotor it should be around 3.8-4 mm. If it > measure more than that it may be the lower compression 9.4:1. But, even > the 9.4:1 should make a noticeable difference IF the stock turbo 20B is > using the 8.4:1 > > Ed > ----- Original Message ----- > From: "bob.kaufmann" > To: "Rotary motors in aircraft" > Sent: Sunday, February 03, 2008 4:44 PM > Subject: [FlyRotary] Low compression rotors > > >> Gang >> >> I have a 20B that I have taken the turbos off and will be using it in an >> aircraft, a RV-10. A friend of mine said that I should use the 9.7 >> compression rotors instead of the turbo rotors. What say you all? >> >> I have pulled the engine off to powder coat the engine mount and if I'm >> going to switch rotors, now is the time before I hang the engine again. >> I >> have the flat plate on milling machine so I could make plates for the 20B >> if >> people wanted. I think I would be competitive. I would like to do them >> in >> groups of ten if people are interested. >> >> Bob K >> Finished except all the parts aren't together yet. >> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: >> http://mail.lancaironline.net:81/lists/flyrotary/List.html > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html >