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

-- http://www.bob-white.com
N93BD - Rotary Powered BD-4 (soon)

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