Hi Paul/Rolf;
I was taking another look at the chamber volume as a function of intake
close angle for porting.
I was using the formulas from the 1981 edition of the Rotary Engine and
my results do not appear to be correct.
Can someone run through the formula/calculation for an intake close
angle of say 45 degrees?
Assuming a 13b:
e=15mm
R=105mm
b=80mm
Thanks
Cary
What page number are you looking at Cary?
Sorry,
'81 Edition, page 14, Section 2.4.2, bottom right - formula 2.24
V=volume
e=eccentricity=15mm
R=Generating circle radius= 105mm
b=width of rotor housing= 80mm
alpha= degrees eshaft rotation
Vmin=minimum volume at TDC (long formula 2.25) =~ 56.5cc or
in the case of a 9.4CR rotor 654/(9.4-1)= 77.9cc
V = Vmin + ( 3 * root(3) / 3) * e * R * b ) * (1 - sin(2/3 * alpha +
pi/6) )
Formula makes more sense if you look at Figure 2.9 on page 15. Shows
the chamber volume
changes as a sine wave based on eshaft rotation compared to a piston
engine.
I just noticed the formula is different in the '71 edition.
3 * root(3) * e * R * b =~ 654cc (swept volume) - the "/ 3" term
appears to be incorrect.
The "/ 2" in the '71 edition appears to be correct.
Still need to work out the intake close timing angle. Not sure if the
alpha value can be replaced with the
degrees of eshaft rotation?
Thanks
Cary
There are errors every once in awhile in the book.
I am not sure I understand the goal here.
I have a lot of intake timing diagrams for both the side
ports and the P-ports verses VE.
Perhaps the angles are expressed in radians and not degrees.
Hi Paul;
When I originally did port timing for the Pport I had to estimate.
Stock port timing are available at:
http://www.yawpower.com/dectech.html
I have seen some of the Pport intake timing diagrams vs VE from some of
the old Mazda tech papers
posted here occasionally - don't recall seeing the diagrams for the side
ports.
I wanted to confirm what the upper limit was for intake port close angle
that intake inertia has to overcome
before compression in the chamber starts pushing it back out when the
intake port is still open.
Had to work backwards to get the degrees of eshaft rotation. Values
look reasonable, I think?
Intake BDC Vmax = 77.9cc + 654.7cc = 732.6cc
30 ABDC - V = 711.8, Vmax/V = 1.029 (6 port 2ndary IC)
45 ABDC - V = 687.2, Vmax/V = 1.066 (40,50 approx side port IC)
60 ABDC - V = 654.1, Vmax/V = 1.120 (RB street port IC)
70 ABDC - V = 627.7, Vmax/V = 1.167 (6port Aux high speed side port, RB
JBridge)
75 ABDC - V = 613.4, Vmax/V = 1.194 (Mazda Factory PPort)
Does anyone happen to know the location of the 13b oil injection port in
degrees ABDC?
Might be useful as a manifold pressure gauge tap.
Cheers
Cary
This is the Lemans engine p-port timing more or less.
Should be able to scale it off the Lemans rotor housing
drawing.
Here are some side port curves.
Paul Lamar ...No rotor no motor.
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