This is my Honda odyssey 250 HP V6.
It appears to have several HR's.
One large one for each bank and auxiliary smaller ones to tune the
torque curve through out the rev range. It works very well.
There is probably is a lot of R&D associated with this design.
Paul Lamar
Here are some diagrams out of the shop manual.
If we can get this to work on the RX8 engine it will be a much more
compact tuned intake and will fit under the typical cowl. We might get
as much as 220 HP at 7500 RPM if we are lucky and one has a 3.12:1 gear box.
Those of you with cut off stock RX8 six port manuals let me know the
dimensions of the plate you welded on. So far Scott and Bob.
My best guess is 4 by 4 by 13 inches long with as 3 inch diameter intake
pipe and throttle body..
If the plate is wider than 4 inches something like
3 by 5 by 13 inches might work.
4.5 by 3.5 might also work.
A Maximite can measure the pressure as a function of RPM for fine
tuning. A 3/8" thick plywood box will work and can be cheaply changed if
the volume needs adjusting based on the Maximite data collection.
Paul Lamar
Paul,
My intake plenum measures 10" long, 4" wide at the base, 3" high at the
throttle body end, and 1 1/2" high on the opposite end. The intake
plenum was made from a piece of 4" thin wall aluminium tube cut in half
lengthwise. The reason I fabricated it at a taper is due to clearance
restrictions needed to clear the engine cowl (hood). Thoughts?
Bob Forbes
It could be resonating at the wrong RPM. Probably too low.
The idea is to have max pressure when the intake port is open.
That is synced to the CAS. (Crank Angle Sensor).
In other words the high pressure is in phase with the intake
port opening.
Try a 4 x 4 a little longer at 13 inches. Rectangular.
Here is a short MM program that measures the intake press starting at
CAS time. It generates a spread sheet file of pressure data. It stores
it on a 32 GIG SD card. Any spread sheet program can plot it.
OPEN "PRESS.DAT" For OUTPUT As #1
SETPIN 1,6,50 'CAS INTERRUPT ROUTINE AT LINE 50
SETPIN 9, 1 'PRESURE DATA IN
DONOTHING:
GoTo DONOTHING 'wait for CAS
50 Print #1 'NEW LINE
60 Print #1 Pin(5)
70 Print #1 "," 'COMMA DELIMITED FILE
GoTo 60
End
This will store the data on the 32 gig SD Card for later reading
on a PC.
BTW some USB keyboards don't work with the MM.
Get a Gear Head brand keyboard and USB to PS2 conn. keyboard adapter.
Paul Lamar
-----------------------------------------------------------------------------
You might get too much data so so you will need to
add a delay at line 70. Some thing like this will work.
80 FOR x = 1 to NNNN ' any number will work bigger = longer
90 NEXT
All this happens at low audio frequencies.
It would be interesting and a lot of fun to insert a microphone in the
resonator
and connect it to your hi fi.
If it is working perfectly you will hear a 200 cycles per second tone
at 6000 RPM.
6000 RPM is 2 sucks per rev. One suck for rotor 1
and another for rotor 2.... 180 degrees out of phase.
That is 12,000 sucks per minute. Divide by 60 to convert
to CPS and you get a 200 CPS audio tone.
Helmholtz resonators are a compact way to tune an
intake manifold. Unfortunately it only works best for
one RPM. That is why Mazda did not use them for the
RX8 engine. They needed to enhance the torque over
a wide RPM range. 3000 to 9000. So they used a bunch
of valves to change the resonant length of the intake system.
Too bulky for use in aircraft and not needed. You need
to tune for cruise RPM.
On the Le Mans 700 HP winning 4 rotor engine it was a trombone
on every p-port rotor. Variable length from 6000 to 9000 RPM.
Paul Lamar
Here is some more data on the subject.
We need to get this working as it will be lower cost than ram tubes,
more compact and take up less room over the engine allowing
a higher thrust line and or a 2 inch shorter landing gear.
Paul Lamar
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