Semi p-port: Does size matter?

N.RotaryTech · 08-28-2015, 02:39 PM

So basically my question is about the size of the hole.

And correct me if I'm wrong on the terminology of:
"Full P-port" or just "P-port" have the intake ports on the irons closed off and there are big holes in the housings.
"Semi p-port" uses the ports in the irons and has holes in the housings as well.
Right?

So back to my question of the size of the holes in the housings for a semi-p-port.
What Ive seen so far on semi p-port builds is a fairly small hole.
So...
What if you go bigger?
Why not go as big as one would go on a "full p-port build?
Do you run into some "volume-metric efficiency" issues?
What if this engine would be turbocharged?

Slides · 08-28-2015, 11:54 PM

You would lose some of the pulse tuning effect as velocities (and hence ram effect) would be lower, not to mention different resonant frequency interference from the side port and PP interacting.

If you look at the per rotor chamber intake volume there are pretty much no other functional engines (maybe a test rotary valve piston engine here or there, nothing brought into production) that has the effective intake area/ flow for chamber size of a decent PP intake.

Turbo charging doesn't change the basic fluid dynamics, but it does change parameters a little bit which will effect the optimised diameter/length of runners slightly. Obviously different intake:exhaust pressure ratios would have to be considered in terms of port timing.

08-28-2015, 02:39 PM	#1
N.RotaryTech Home-brew Rotary Join Date: Feb 2008 Location: GooseCreek SC iTrader: (0) Posts: 552 Rep Power: 17	Semi p-port: Does size matter? So basically my question is about the size of the hole. And correct me if I'm wrong on the terminology of: "Full P-port" or just "P-port" have the intake ports on the irons closed off and there are big holes in the housings. "Semi p-port" uses the ports in the irons and has holes in the housings as well. Right? So back to my question of the size of the holes in the housings for a semi-p-port. What Ive seen so far on semi p-port builds is a fairly small hole. So... What if you go bigger? Why not go as big as one would go on a "full p-port build? Do you run into some "volume-metric efficiency" issues? What if this engine would be turbocharged? __________________ '89 RX7 GTU, half-Bridge-port S4/S5 NA, E6K, Full RB exhaust, weekend warrior. '83 RX7, The "this might take awhile" project. '87 RX7 GXL, Rest In Pieces. '98 Subaru Impreza Outback-sport, rx7 rescue vehicle, down for repair. '94 Ford Ranger, daily.

08-28-2015, 11:54 PM	#2
Slides Rotary Fan in Training Join Date: Apr 2012 Location: NSW, Australia iTrader: (0) Posts: 39 Rep Power: 0	You would lose some of the pulse tuning effect as velocities (and hence ram effect) would be lower, not to mention different resonant frequency interference from the side port and PP interacting. If you look at the per rotor chamber intake volume there are pretty much no other functional engines (maybe a test rotary valve piston engine here or there, nothing brought into production) that has the effective intake area/ flow for chamber size of a decent PP intake. Turbo charging doesn't change the basic fluid dynamics, but it does change parameters a little bit which will effect the optimised diameter/length of runners slightly. Obviously different intake:exhaust pressure ratios would have to be considered in terms of port timing. Last edited by Slides; 08-28-2015 at 11:59 PM..