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Ok, Scott
Here is how I see it.
1. The six port does present a bit more of a challenge, but here are some
considerations.
a. The primary port and secondary ports are on different sides of the
chamber, so for 1st order estimation you can probably consider the two ports
separate as they would have to interact through and across the width of the
rotor chamber. Now that is with the stock manifold setup which keeps the
primary and secondary port airpaths separate. That being said, you could
use the opening and closing of the primary and secondary/Auxiliary port
times for your calculations. I would use the primary opening and closing
for the primary length calculation and for the secondary I would use the
secondary opening and the auxiliary closing times. I suspect that the
opening of the primary port and then shortly thereafter the secondary port
would have most of the residue exhaust gas exiting the chamber so that the
opening of the auxiliary would probably not contribute much to the pulse
formation. However, its late closing means it could provide some benefit in
extending the rpm range of the DIE effectiveness.
b. Merging the primary and secondary does (in my opinion) present a bit more
of a challenge. I have done that on my turbo block but only because I
ported both my primary and secondary to have the same port timing.
Therefore the pulse generation occurs for both at the same time. The pulse
will most arrive at the primary port slightly before the secondary due to
small variances in the path length of each, but I do not believe it would be
a significant factor. I am not certain what Merging the ports on the six
port with the stock port timing will do - but, my best guess is that it
would provide a less intense DIE effect over a broader rpm range.
c. Right now I am running a manifold that has a nominal length of 48" port
to port (24" from port to Throttle body), I am getting 5800-6000 rpm static
on these cooler mornings (with the 2.85 gear box and 76x88 prop). That
length would give normally me 5600-5800 static with the 2.17 gear box (and
68x72 prop) on the cooler mornings.
I am not certain I understand your reference to your 50" port to port and
the 20" and 30" figures. If you have calculated that 50" is your port to
port distance then you would ideally have 24" from port to throttle body.
You indicated you had 20" (which I presume is your runner length which
combined with manifold and block paths should give you right at 24-25" path,
so not certain why/where you want another 30". The port-port distance is
from the primary/secondary of one rotor to the primary/secondary of the
second rotor. So if that is 50" and assuming you want balanced runners with
the throttle body in the middle then the TB to port length would be on the
order of 25" which with your 20" runner and manifold/block path probably
gives you what you are looking for.
But I may not have understood your question on the lengths, get back to me
if I misunderstood based on the above.
Hope this helps
Working on new exhaust muffler
Ed Anderson
----- Original Message -----
From: "Scott" <squiggles@yahoo.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Monday, November 08, 2004 9:08 AM
Subject: [FlyRotary] die on a 6 port
> Good Morning...
>
> A 6 port engine having the auxiliary and secondary
> ports with, I am assuming here, their own respective
> wave opening and closing events. Now only one intake
> runner serving both ports, which port/wave event do
> you time your intake runner length to?
>
> The auxiliary as this is the port which opens later
> and closes later? But, I then miss the exhaust burp,
> A pulse?, as this went with the opening of the
> secondary port...
>
> If I choose the secondary, then my intake charge leaks
> out when the auxiliary opens.
>
> Perhaps a 6 port was not the wisest of choices?
>
> I had originally thought I would use the opening of
> the secondary port and the closing of the auxiliary
> port as my starting point for capturing the DIE. This
> led to a port-to-port of somewhere in the 50" range.
> Well, I have 20" on runner welded up, then started
> thinking where was I going to find another 30" under
> the cowl. Now I do have a lot of room under the cowl,
> but the 30" just started to sink in...
>
> Thank You.
> -Scott
>
>
>
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