what is everyone talking about when they say running the 5th and 6th ports open? or take off the air pump. What does the air pump do, and what exactly are these ports. i'm new to rotaries. thanks in advance.

 

Most people would say something like *search* but I don't like to point out the obvious, so I won't.

But just to let you know the search function on this site is REALLY good.

 

here, i'll help: www.howstuffworks.com

search for rotary and look in the right hand list

 

This site has a section explaining ports, etc. with cool animations:
http://www.rotaryengineillustrated.com/index.html

 

The N/A RX-7 has 6 ports, or "holes" leading into the engine to feed the air-fuel mixture.

In order to conserve low-end torque, only 4 ports are open in the lower- rpms. Around 3800 rpm, the 5th and 6th ports, or "auxilary" ports open, and more air/fuel is able to flow into the engine. Think of it like a VTEC.

Modding the RX-7's, as well as a porrly functioning system, can cause these ports to remain closed, killing top-end power. In 86-88 NA's, the ports open via exhuast back pressure, and in 89-91 NA's, the ports open from air pump pressure. Addition of a free flowing exhaust to the 86-88's will cause the auxilary ports to remain closed, and removal of the air pump on 89-91's will cause the auxilary ports to remain closed.

A cheap fix for this is to wire the ports open. There are manual actuators external to the engine, and people simply hold these actuators in the open position permanently with zipties or wire. This lowers bottom end power, but brings back the top-end.

The air pump also pumps air into the exhaust to lower emissions.

 

http://homepage.mac.com/jburger/jaysrx7/6PortSolution/
http://home.earthlink.net/~burntoast/6port.html

http://www.mazdatrix.com/faq/port6p.htm
http://www.mazdatrix.com/faq/portintk.htm
http://fc3s-pro.com/TECH/PORT/porting.html
http://www.geocities.com/MotorCity/P...8/porting.html
http://www.rotaryengineillustrated.c...-ports101.html

NAs are 6 port. Turbos use 4. NAs run on 4 until a certain rpm and switch to 6 for better intake flow. S4(86-88) used exhaust backpressure to open ports as the rpm rises. S5(89-92) were controlled by the ECU and use the airsmogpump/solenoid....to open the ports via actuator....... They tend to fail either by actuator quitting or sleeves getting stuck. Some people wire them open and loose lowend torque. But, other mods will make up for lost power.

 

so if i have a 87 t2 i don't need to worry about ports opening and closing?

 

nope you only got 4.