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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