Return-Path: Received: from goose.mail.pas.earthlink.net ([207.217.120.18] verified) by logan.com (CommuniGate Pro SMTP 4.2.4) with ESMTP id 455484 for flyrotary@lancaironline.net; Wed, 06 Oct 2004 18:24:57 -0400 Received-SPF: pass receiver=logan.com; client-ip=207.217.120.18; envelope-from=Dastaten@earthlink.net Received: from user-0cetjkt.cable.mindspring.com ([24.238.206.157] helo=earthlink.net) by goose.mail.pas.earthlink.net with esmtp (Exim 3.33 #1) id 1CFKCy-0006i5-00 for flyrotary@lancaironline.net; Wed, 06 Oct 2004 15:24:28 -0700 Message-ID: <41647038.6070205@earthlink.net> Date: Wed, 06 Oct 2004 17:22:48 -0500 From: David Staten Reply-To: Dastaten@earthlink.net User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Street Porting question References: In-Reply-To: Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit

PhilWhite9@aol.com wrote:

I read on Craig's rotary site references to 'street porting' the engine to improve breathing and power output, but I haven't seen any mentions of port modifications during the 5 months I've been reading this group's postings.

Is there info in the archives, or another site that would provide diagrams or photos of what is done to the ports to improve breathing?

I am rebuilding my 20B as a normally aspirated engine to install in the RV-10 I am building, and the 240 HP from stock is a little less than I would like. Any input would be greatly appreciated.

Phil in Willowbrook, RV-10 #40220

I am in the process (well, I am working at it slowly) of porting out a 13B 2nd gen Turbo engine. I am using the streetable port templates from racing beat. I have never done this before. I have no experience with metal smithing. I am using a dremel with both a carbide bit and a bullet-shaped grinding stone. I also have an air powered grinding die set but most of the work is with the dremel.

I have at this point only ported the intake ports on a normally aspirated intermediate housing (a junk core, for practice) that I obtained from Chris Barber, the airframe builder for the project I am working on.

So far, what I can say is:
1) be patient and deliberate. The porting templates are thin aluminum, and it is very easy to grind/cut beyond the scribe lines provided by Rading Beat.

2) The intake template is a "one size fits all" approach. The housings have some difference in water jacket configuration and as a result you need to pay attention to detail or you WILL breach a water jacket if you just grind away all the metal the port template prescribes. Take your finger and feel behind the polished surfaces by reaching through the water jacket holes and you will see what I am referring to (on the turbo intermediate housing). On the NA intermediate housing there is some sort of plenum chamber that is connected to the intake that has a lot of cast metal there. The NA intermediate housing is able to be ground away completely within the outline of the porting template if you contour it.

3) be patient and deliberate. You cant replace metal you have ground away, and when you are nearing the edges of the area you are porting, it is VERY easy to slip and score/grind the polished surface and damage the chrome/polished surface.

4) the streetable exhaust port doesn't prescribe for much metal removal. You would do well to get Turbo rotor housings that do not have the diffuser in the exhaust stream (Bruce Turretine recommends this in his video as a performance upgrade)

I will post some pics later. I am working an awful lot this week, and I just spent two days offline because a storm toasted my cable modem, so I am playing catchup.

Dave Staten
Houston, TX