it appears that the use of peripheral port intakes provides a

significant advantage in power for the rotary engine.  Because of the
agressive timing on a peripheral port, however, it seems that a major
problem associated with this type of intake is very poor idling
characteristics.  How bad is it really?  I know that Powersport is using a
butterfly valve at the port opening to improve air  flow characteristics and
velocity at low engine speed.  They also have intake tubes that are less
than 1 and 1/2 inches in diameter, which increases airflow velocity and
improves idle characteristics, when compared to the huge port openings that
Racing Beat offers.

Before I spend a lot of money on the modifications necessary to convert a
Mazda 13B to a peripheral port intake engine, I would like to get a more
thorough discussion of the pros and cons, along with the technical aspects
of what effect the peripheral port has on overall engine performance.  Does
anyone know of a book, treatise, technical paper or other comprehensive
discussion on the subject, including actual data on just how poorly the
engine really idles?

I have both peripheral port and pridge ported motors. I have never recorded the opening and closing events of these engines, but my guess is that the bridge ported engine has a bit more opening period than the peripheral port. The peripheral port will idle down to 1200 RPM before it starts bucking and poping. The bridge port starts acting up at about 1500 RPM. I set the idle for both at 2000 RPM. This is to help keep it running no matter how hard the driver spins the car, or slides it backwards in the grass. It also sounds better with the classic rump...rump...rump. I built a set of 12A periphery port housings with Devcon Plastic Steel and some exhaust pipe tubing. I put the housing on top of a factory periphery port housing and copied the port events with a small square. The advantage for aircraft use would be loosing most of the intake manifold weight (using tubing). Try it on a damaged housing. It's easy.  Lynn E Hanover

 
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