Ed,

I guess you have seen the Mazdatrix web site where they discourage the whole porting thing with a 6-port.  Just the opposite of what Lynn proposes. 

Bill

 

Well,

actually I did say that the closing point should not be later than 60-65 degrees ABDC. And I'm sure that you noticed that the 6 port closes at 70 degrees. Compared to the Periphery ports 75 degrees or he "J" bridge ports (Racing Beat) 72 degrees. So the 6 port is real racy in stock form. And all of the talk about not porting the 6 port irons leaves out the point that they sell templates to port the 6 port irons. In fact the Owner, Dave Lemon races an E Production Mazda convertible with a 6 port engine with irons hogged out to form a 4 port engine. And it does suck real bad down low, torque wise from low velocity flow. It come on like gangbusters all the way up above 10,000 RPM.

 

So, a 6 port is not really a great choice for airplane use, but it is not a disaster like it would be in a street car. The idea is that once it gets up to RPM, the effect of late closing is minimized. The run up to RPM would be longer than an early closing intake. Like WOT in a panic, but that is not a deal breaker. .

 

The 6 port adds pieces and complexity to an engine few people understand. But if you are crazy about rotaries like me, it won't bother you at all. Just understand what you have and work with that.

 

Lynn E. Hanover