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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
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>
>
> On Thursday, January 6, 2005, at 01:28 PM, Russell Duffy wrote:
>
>
> My p ports open at 78º BTDC and close at 75º 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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