Rotary Engine Porting

Porting Basics

There are various ways to port a rotary engine, from street applications to full race applications.  Theses can also be referred to mild extended ports (street), to peripheral ports (race).  Regardless if the engine is turbo or naturally aspiration, all engines can be ported.  Typically a wankel that has a turbo will receive a mild or extended street port, while bridge porting will be extremely rare for turbo applications.

Even though porting is a great option to increasing performance, there are significant amounts of swapping the 13B Turbo motor for a naturally aspirated one.  This is because of the low prices and increases reliability of the newer motors.  But for the true enthusiast they will swap a turbo and still port the engine, a good rotary porting job sounds is music to car enthusiasts.   

Did you know that porting is one of the most tried and tested methods of increasing horsepower in the rotary engine.  This is because throughout the long history of the rotary engine, there have been countless race cars, and street cars that have had positive results in porting their engines.  The porting process basically involves reshaping and or enlarging the front, middle, or rear end plates and exhaust ports of the motor.  In general it’s the same idea as porting a conventional piston efficient – but in effect it will also change the cam timing and lift at the same time for piston engines.

While modifying the porting area you will want to look at the runners that feed the working chambers.  For piston engines to increase horsepower they usually buy aftermarket cams and sometimes purchase ported heads that have been polished.  The cams on a piston engine may alter the lift, timing, duration and or overlap.  The porting increases the airflow in the engine which produces dramatic results.

There are many variables that can be changed while porting to achieve specific goals.  Do you want a full race motor, a quick street car, or something between the two?  So what should you do with a rotary engine to change theses variables?  A lot of people know that wankels use fixed ports that are opened and closed by movements of the working chambers.  There are no cams, or valves.

So we are not stuck with the factory specs are we?  Of course not, you can accomplish porting with a die grinder for huge power hands.  Also we might add, its also incredibly easy to kill your engines performance if you mess up the job.  Here is a cost saving strategy, try porting on some already damaged plates.  After your done bring them to an expert and have them quickly analyze the ports to see if you even did a good job.  Although if you do this, make sure you make it worth the engine builders while give him a free food card or something.  I guarantee that if you walk into a shop ask for suggestions and leave without anything in return that is really bad business.  Especially because they are trying to make a profit off porting!  On the other hand, if you provide something good for the engine builder, not only will he do a better job teaching you what to improve on, he’ll like you more and it’ll build your network. 

Porting Options:

1. Pay rofessionals
2. Purchase porting templates
3. Learn about porting and attempt it yourself.

Regard less of which option you choose, it is generally recommended to learn about how and why porting works so you get a better understanding to whats going on.

Many variables to choose from:

1. Changing the advance opening timing
2. Modify the extended port closing
3. Adding a lift
4. Increasing overlap
5. Chaning how quickly ports open and close.