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Date: Thu, 6 Jan 2005 14:15:16 -0700
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: P-Port stuff-  was Re: RV-3 engine rebuild
Message-Id: <20050106141516.78a6f0eb.bob@bob-white.com>
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I figured worst case it has to breathe better than the cast iron
manifold with a straight pipe.  I just hope it muffles pretty good too.
On the inlet side, I have a street port which won't flow as well as your
Pport Jerry.

When I was looking at tuned pipes, it seemed like the correct length
ended up with the muffler at a very awkward location so I had sort of
given up on tuning them anyway.

If your exhaust system flows as well as a stock exhaust and cuts the
sound level to something I can fly with I'll consider it a success.

Bob White


On Thu, 6 Jan 2005 15:19:49 -0500
Jerry Hey <j-winddesigns@thegrid.net> wrote:

> > Ken,  There are no test results.   It is all theory  and wishful 
> > thinking at this time.  Bob White bought an exhaust system, even 
> > though it is unproven, and he will be the first to test it.  I am
> > sure 
> >  your comments have gotten  his attention today.  I forget how long 
> >  
> > the tuned exhaust pipe is  supposed to be.  I do recall  it was long
> >  enough there was no hope of getting one inside the cowl and then
> >  there 
> > is that muffler hanging out in the breeze. I can't see that on a 
> > Tailwind.  Drag and weight are penalties of the tuned exhaust. As
> > far  as performance is concerned it might be a wash.  No one knows
> > until we  do the tests.
> >  BTW,  the exhaust pipe on my system has much greater capacity than 
> > the combined two inch pipes of a tuned system.  Easy breathing is
> > what  I am hoping for.   Jerry
> >


> 
> On Thursday, January 6, 2005, at 02:04  PM, kenpowell@comcast.net
> wrote:
> 
> > Hi Jerry,
> > As you know I am also a great proponent of Pport.  Since I am
> > building  a RV-4 room is a problem under the cowl (Rusty knows what
> > I mean!).   While your exhaust would solve many problems for me I
> > think you are  going to be disappointed in the HP output without the
> > scavenging  effects of a properly tuned (and pipes merged) exhaust. 
> > I hope you  prove me wrong, but I hope you are flexible in your
> > design to add full  length pipes.  I suspect the untuned exhaust may
> > cost as much as 30 HP  (yes, this is a real swag without any data to
> > back it up so it isn't  worth much).  Do you have any test results
> > (from anybody) to show the  results of a short untuned pipe?
> 
> > Ken Powell
> > Bryant, Arkansas
> > .
> >

> >
> > -------------- Original message --------------
> >
> > >
> > >
> > > On Thursday, January 6, 2005, at 01:28 PM, Russell Duffy wrote:
> > >
> > >
> > > My p ports open at 78__ BTDC and close at 75__ ABDC. This
> > > drawing shows how much later the ports open in comparison with the
> > > Leman P Port and how they close at nearly the same time. According
> > > to calculations made by Rolf Peiffer who helped me a lot, my
> > > little port has sufficient capacity up to 8000 rpm. After that you
> > > would want to go bigger. The exhaust port was left stock with the
> > > splitters in. . JerryArialFFFF,0000,0000
> > > r>
> > >
> > >
> > >
> > > ArialFFFF,0000,0000Thanks
> > > for the info, and pic Jerry. Do you have an estimate of how much
> > > HP you expect to make at 7500 rpm? And can you get that thing
> > > running in the next month, so it will be easier for me to decide
> > > what to do :-)
> > >
> > >
> > >
> > > ArialFFFF,0000,0000Cheers,
> > > or>
> > >
> > > ArialFFFF,0000,0000Rusty
> > > >
> > >
> > >
> > >
> > > Rusty, The hp question???? A worse case scenario I feel would be
> > > 230 hp at 7500. I think around 250 hp is realistic if we can get
> > > it up to its potential. It depends on so many factors that will
> > > have to be ironed out on the dyno. I have a 2:17 drive and a 800
> > > lb airplane so if I equal PowerSport's performance of 215 at 6000
> > > that would be sufficient to get the heart pumping on climb out.
> > > That said, I think PowerSport's intake is too long and also they
> > > could benefit 
> > from
> > > ram air. So maybe I will do a little better then they have. My
> > > exhaust is a free flowing, zero back pressure design and I am
> > > hoping it will help too. Best thing for you to do is to haul that
> > > engine to Lynn"s and knock out a p port in a couple of days. Jerry
> > >
> > >
> > >
> > >
> >
> 


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