capn

hey all

i have been looking at alot of rotary engines lately and i was wondering wouldnt it be better to have a very LARGE opening for the intake that would allow more airflow



you see that the intake is relatively small and it has that whole big space that it could be ported, is there a reason why the intake is so small?

RETed

Intake (duration) timing
It's a bit involved to get into the details, but if you open it too early you run into overlap problems.  If you open it too late, the intake duration starts to butt into the ignition cycle, which could backfire up through the intake.


-Ted

capn

so the intake also determines at which rpm range the power is made, compression starts, and all that because the lack of valves and such.

so when porting is the area made larger or is it just smoothed?

RETed

Yes, basically.


Both.
Depending on what year engine and turbo or non-turbo, you can increase duration by going "higher".  The stock ports can easily be ported to increase duration by doing this.  Be careful with going overboard, as some engine types (notably FC turbo) irons cannot be ported a lot doing this due to a very thin water jacket.

http://www.mazdatrix.com/faq/cutaways.htm

A lot of shops also port "back", which increases overlap, but there is a limit where the corner seal falls into the hole - this is where bridge porting comes in to keep the corner seal from falling into the intake port.

Peripheral porting is the ultimate in intake porting, but this introduces huge amounts of overlap which kills low-end power.  A PP motor does increase top-end power substantially.


-Ted

Project84

Your original statement says You forget that the view shown in your picture shows the rotor in the rotor housing minus the center plate. There is another intake opening in the center plate, so the one you see in the picture is not the only opening for the rotor to get air/fuel.

GUITARJUNKIE28

i just throw wome epoxy behind the port wall and have at it...haven't had a failure yet.