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----- Original Message -----
From: "Marvin Kaye" <marv@lancaironline.net>
To: <flyrotary@lancaironline.net>
Sent: Monday, September 16, 2002 6:37 PM
Subject: [FlyRotary]Re: 13B EXHAUST PIPE LENGTHS
>
>
> Posted for "GERYVON" <geryvon@sympatico.ca>:
>
>
> > Yvon, I could not readily find a photo of my current system. But here is
a
> > photo of its very similar predecessor. The primary difference in the
two
>
> Thank you for this info, Ed
> Listen, your exhaust pipes do not look to be 31" long. Am I mistaken?
> Yvon Cournoyer.
>
You are correct, Yvon, my header pipes are around 27-29" long to the end
of the header (see bitmap of CAD drawing of my header), however there is
another 6" of the exhaust tubing that is unpunched so that probably
effectively adds to the length a bit. I am pleased with the power output in
that I routinely turn 5200-5400 static rpm and have had as much as 6100 at
WOT at 3500 MSL.
I think my power is restricted at this point by my intake system. The
reason I say that is that if I am WOT and pulling 6000 rpm in level flight,
you would think that by lowering the nose and picking up airspeed I would
unload the prop and my rpm would increase. However, I have tried this on
several ocassions and while the airspeed did indeed increase, the rpm did
not increase indiciating a restriction in the intake (I guess it could be a
restriction in the exhaust, but they are pretty much open tubes). I run
with my intake runners 2-3" longer than Tracy's so that might move my rpm
peak down a bit. I am going to adjust my runner length by about 2-3"
shorter and see if that makes any difference. Also the inside of the intake
lower manifold is somewhat dirty to airflow.
Ed
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