what is the diffrence between a s4 and s5 n/a header???

 

are you talking about the stock exhaust manifold? if so, there is no difference between the 2. i believe they have the same part numbers, and are interchangeable.

but for some reason i recall mazdatrix having 2 different gaskets for S4 and S5...hmmm...

 

ive used the same header on my 88' and my 91'....... and the same gaskets....so, they are interchangable....without ANY modifications!!!

 

yup, 2 different gaskets on mazdatrix, and they look different also!
http://www.mazdatrix.com/e6.htm

the one they have listed for the S5 NA seems to be missing a hole though...

 

The extra hole would be to activate the 5th and 6th ports on '86 to '88, while the '89 to '91 dont have this hole as the ports are activated by the air-pump.

 

the auxilary port activation has nothing to do with the exhaust manifold. the differences for that are found in the lower intake manifold.
i still don't know why the gaskets would be different though.

 

so what would the hole in the stock manifold be for???
Its blocked off right now as I have a header.
Would it be for the EGR?

 

The S4 uses exhaust backpressure to open the 5th and 6th ports so Ive heard. The port on the S4 mani would be for that.

EDIT: Check out the FC FAQ page at https://www.rx7club.com/2nd-generation-specific-1986-1992-17/faq-fc-frequently-asked-questions-2nd-generation-rx-7-a-181219/ and look at post # 4.

 

technically the stock piece is a collector not a header and who cares, slap a turbo on there.

 

yes, i am well aware of that, however i am saying that the exhaust manifold has nothing to do with opening the aux. ports on the S4. the exhaust backpressure comes from a split air pipe connected to the main catalytic convertor. this goes to the LOWER INTAKE MANIFOLD.

 

The extra hole is for the EGR. PERIOD. It has nothing to do with the opening of the auxillary ports on a series four car. PERIOD. i'm on my period. humor

Exaust gas pressue FROM the catalytic converter opens the auxillary ports on a series four. Neither the airpump nor the hole in the exaust manifold have a thing to do with the opening of the auxillary actuators. See the FSM that is free and online.

Just repeating one of the posts above.

 

How did 6pt get into a thread about headers???? Or I should say stock manifold.