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
.

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


-------------- 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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>