| Back to my question:
P-Port pros: power, simple, reliable, NA cons: tuning, long intakes, rebuild (assuming you have a side port built already)
Turbo pros: power, tuning less of a factor, short intakes, use side port short block, altitude compensation cons: more complicated, less reliable, more heat?
We haven’t really discussed different compression rotors. But the Renesis has high compression rotors and is less suitable to turbo charging without altering the rotors, right? If you already have a motor built with side ports and low compression rotors (13B REW, 20B), it is ready for a turbo, but P-Port would entail a significant rebuild, right?
Not the case for a turbo installation. Both the exhaust and intake of turbo
systems are just long enough to mount the turbo. Once you have the intake charge
well above ambient pressure, not much length tuning is needed.
The ports and runner sizes in the turbo irons are enormous.
In the normally aspirated Pport both intake and exhaust lengths and
diameters make a big difference. Note the Mistral runner lengths. ( a side port
engine). Similar lengths would put best power in a Pport at a similar RPM. The
biggest effect will be muffler design. NA rotaries tune like dirt bikes. Very
sensitive to exhaust length, diameter and back pressure. The Le mans engine had
adjustable inlet lengths because it was an NA engine.
Lynn E. Hanover
Bill,
You couldn't be more incorrect. The P port is VERY
tuneable. Witness the LeMans 26B which had variable length intakes to improve
driveability across the rev range. You just need to alter your thinking a bit.
The rotor IS THE VALVE. When in the intake phase tuning length is very
effective. A turbo works similarly, but length isn't as critical. Obstruction
is more important in the turbo version. If the path is clean and free of sharp
corners the turbo doesn't work as hard and doesn't heat the intake charge as
much. Less need for an intercooler. Bill Jepson
On Oct 7, 2015 4:35 PM, "Bill Bradburry" < flyrotary@lancaironline.net>
wrote:
If I understand the
situation, and believe me, I probably don’t….a tuned intake would give a
turbo more power at a given boost pressure than it would have untuned at
that same boost pressure. However, the benefit might not be worth the
effort due to the small incremental
difference. On the other hand,
a P-port is never closed so there would be negligible reflected waves to use
for tuning. The rotor apex seal slides by the opening of the port and
slices off the fuel/air charge that is going to one rotor face and it starts
to be directed to the other face. Think of the intake air column as a
sausage that is being sliced off as the apex goes by the open port.
Very little reflectivity to use for tuning. Or more likely, I
could be wrong. Bill
From:
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Wednesday, October 07, 2015 11:39
AM
To: Rotary motors
in aircraft
Subject:
[FlyRotary] Re: To P or not... One more question to throw into the mix. A
friend is building a Cozy and has 13B short block, currently believed to be
fresh though compression and leak down tests remain to be done. He is
now thinking to go turbo instead of tearing it down to go P-port. Is
it true that there is no intake runner tuning for a turbo setup? Yes
it is more complicated to go turbo (than peripheral), but there is also the
advantages at altitude.
So the extra question is: P-port or
turbo?
Christian, While you are
doing that, you could also include some info on your pporting of the
Renesis. How did you know where to bore the holes for proper timing
and how did you seal the water jacket? I assume that you just
plugged up the original ports with JB weld or
something? Thanks, One of the other
Bills
From:
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Wednesday, October 07, 2015
9:04 AM
To:
Rotary motors in aircraft
Subject: [FlyRotary] Re: To P or
not...
can you give details on your
custom built hotdog with inox?
baffling.
Sent:
Tuesday, October 06, 2015 11:08
PM Subject:
[FlyRotary] Re: To P or
not...
I would agree, yes it worked
out to be allot more simpler running 2 x 2" runners than playing with 4 in
my opinion and easier to manufactur
etc From modifying my engine
from a not so good 6 port intake to a simple 2 port intake I gained a good
30-40 hp and 15 k top
end The noise also isn't that
bad on my renises as I've attached a custom built hotdog underneath with
inox baffling which works
well
Trying to ensure I have a
complete knowledge before I make my
decision, The P port as shown for
the website is exactly what we are looking for. Straight forward power
at high rpm. The noise is a factor of energy output which is the
same. If I tune a 4 port runner
system and get x amount of air into the engine I give y amount of fuel
and I have z amount of power and engine exhaust/noise to
handle. If I use a P port and get
x amount of air and give y amount of fuel it is the exact same z
output. It was just easier to get x amount of air into the
system. Or am I completely off
base.
Bob,
One thing that
everyone should get clear is that for aircraft PPorts are almost
always superior. At higher RPMs. Also Pports will idle just fine. Good
balance and vibration control are the key to good idle. The engine
won't make a lot of power at low rpm but that isn't a problem for an
aircraft. The rotary makes a better aircraft engine than a car
engine! Bill
Jepson
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