X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from relay04.roc.ny.frontiernet.net ([66.133.182.167] verified) by logan.com (CommuniGate Pro SMTP 4.3.5) with ESMTP id 1020333 for flyrotary@lancaironline.net; Fri, 24 Jun 2005 11:22:42 -0400 Received-SPF: pass receiver=logan.com; client-ip=66.133.182.167; envelope-from=canarder@frontiernet.net Received: from filter04.roc.ny.frontiernet.net (filter04.roc.ny.frontiernet.net [66.133.183.71]) by relay04.roc.ny.frontiernet.net (Postfix) with ESMTP id 4E888358293 for ; Fri, 24 Jun 2005 15:21:58 +0000 (UTC) Received: from relay04.roc.ny.frontiernet.net ([66.133.182.167]) by filter04.roc.ny.frontiernet.net (filter04.roc.ny.frontiernet.net [66.133.183.71]) (amavisd-new, port 10024) with LMTP id 03246-01-79 for ; Fri, 24 Jun 2005 15:21:58 +0000 (UTC) Received: from [127.0.0.1] (67-137-93-70.dsl2.cok.tn.frontiernet.net [67.137.93.70]) by relay04.roc.ny.frontiernet.net (Postfix) with ESMTP id 8FF10358381 for ; Fri, 24 Jun 2005 15:21:57 +0000 (UTC) Message-ID: <42BC250C.3030600@frontiernet.net> Date: Fri, 24 Jun 2005 10:21:48 -0500 From: Jim Sower User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040514 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: PP debate was Re: Single PP HP? References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------030608050909030502070505" X-Antivirus: avast! (VPS 0525-4, 06/24/2005), Outbound message X-Antivirus-Status: Clean X-Virus-Scanned: by amavisd-new-20040701 (2.0) at filter04.roc.ny.frontiernet.net This is a multi-part message in MIME format. --------------030608050909030502070505 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit <... starting to give some thought to building a test stand ...> That's a really good idea. You could use any prop that was flying on a plane and giving known performance and static rpm as a benchmark and go from there. It would only give you static rpm which you could use to estimate power for that rpm, but projecting that to higher rpm's would seem to be more accurate than anything we've got now. How elaborate would something like that be and what would it cost? ... Jim S. Russell Duffy wrote: > I have the same but haven't removed the deflector out of the exhaust > port yet. Any idea on the difference with or without? > > Hi Georges, > > This is another one of those eternal debates on the list. I think the > consensus is that they must cost some power, but maybe not even enough > to notice. They are said to make a noticeable difference in exhaust > noise though, which is a good thing. So far, I've only used the turbo > housings, which don't have the splitter. > > I sure wish I had a big Lottery check, so I could install a dyno, and > spend enough time playing with these things to figure it all out. > Short of being able to do that, all we can do is collect any info we > can from the sources we have. Unfortunately, this data rarely > compares directly with what we need, and by the time we try to > mentally convert the conditions of the test, the results are skeptical > at best. > > One example of this is Lynn's numbers for ported and PP engines. > While I really do appreciate the data, it wasn't quite the gold mine > of info I was hoping for. There are just too many variables, such as > racing choke limitations, which I can't account for. I'm afraid I > still don't know what the real difference between a side and > peripheral port engine would be. > > I have to admit that I'm starting to give some thought to building a > test stand, and having some way to measure power. Perhaps just a good > mixture monitor, a big variable pitch IVO prop, and reliable fuel flow > measurement. Short of having a real dyno, I'm not sure what else I > could do. > > Cheers, > > Rusty (buying more lotto tickets) > > > > > --------------030608050909030502070505 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit <... starting to give some thought to building a test stand ...>
That's a really good idea.  You could use any prop that was flying on a plane and giving known performance and static rpm as a benchmark and go from there.  It would only give you static rpm which you could use to estimate power for that rpm, but projecting that to higher rpm's would seem to be more accurate than anything we've got now.

How elaborate would something like that be and what would it cost? ... Jim S.

Russell Duffy wrote:
Message

I have the same but haven't removed the deflector out of the exhaust port yet. Any idea on the difference with or without?

Hi Georges,

This is another one of those eternal debates on the list.  I think the consensus is that they must cost some power, but maybe not even enough to notice.  They are said to make a noticeable difference in exhaust noise though, which is a good thing.  So far, I've only used the turbo housings, which don't have the splitter.

I sure wish I had a big Lottery check, so I could install a dyno, and spend enough time playing with these things to figure it all out.  Short of being able to do that, all we can do is collect any info we can from the sources we have.  Unfortunately, this data rarely compares directly with what we need, and by the time we try to mentally convert the conditions of the test, the results are skeptical at best.  

One example of this is Lynn's numbers for ported and PP engines.  While I really do appreciate the data, it wasn't quite the gold mine of info I was hoping for.  There are just too many variables, such as racing choke limitations, which I can't account for.  I'm afraid I still don't know what the real difference between a side and peripheral port engine would be.     

I have to admit that I'm starting to give some thought to building a test stand, and having some way to measure power.  Perhaps just a good mixture monitor, a big variable pitch IVO prop, and reliable fuel flow measurement.  Short of having a real dyno, I'm not sure what else I could do.

Cheers,

Rusty (buying more lotto tickets) 

 

 

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