Cobra_R

Sorry if this has been mentioned but i searched and coudnt find anything on it.
Okay so the S4 5th and 6th ports open with the backpressure, while S5's use the airpump. Installing an exhaust on an S4 causes the 5th and 6th ports to not open. So i was wondering, could i just connect the 5ht and 6th ports to the airpump like in an S5, and after doing that then the 5th and 6th ports would open and i wouldnt have that loss of HP right? Also if i can do this how would i do it, what parts i need etc. I dont really want to wire the 5th and 6th ports open cuz i heard you loss low end HP. What other ways are there of doing this?

Ronac

The diaphragms that open the ports are different. The s4's use a vacuum to open them while s5 uses air pressure. If you want to use an airpump, then you will have to fit s5 diaphragms onto you lower intake manifold. Then you'll need a rpm switch connected to a valve to control when the diaphragm gets air.

Or

You can take out the sleeves and rods all together.
That's just what I did to my s5.

Dom_C

ronac is wrong on this one. you can hook your 5th and 6th ports up to your air pump and it's really simple and really cheap. go to the hardware store and you'll have to get about 1 foot of tubing and one small, about 1/4, coupling. you hook that line up to the aux ports in the same spot then you connect the other end of the tube into the bottom air pump tube, which i beleive is the acv releife line. this line puts out about 2-3 psi at about 3800-4000 rpm's so the ports open at just about the same time as stock. this works i did this to my car after gutting the cats and it worked great. i have a picture of how to do this but don't know how to post pictures i'll try to figure it out.
Dom

Ronac

How can you open them using pressure when they are designed to open with pressure?
And the rpm that they open at are very inaccurate if you do it that way. How can you guarantee they open at around 3800-4000?

Dom_C

ok heres the link to the thread i used to do this mod. https://www.rx7club.com/showthread.p...5&pagenumber=2
there is a good picture on thre and tells you exactly how to do this mod. Like i said it worked great for me. good luck
Dom

Ronac

Sure..
Doesn't really matter to me because I have no 6 ports anymore.

Dom_C

dude, don't flame. this works great. i'm trying to help another fc'er check out the link. i know this works because i have done it. you can see the actuators move when the rpm's hit around 3500 rpm's and finish a little aboove 4000 rpms. i'm not trying to start any arguments. this way works and it's a good alternative to stock. no low end loss and still get to keep the high end. it's a good deal. plus he can do all the exaust mods he wants now. give it a try you'll be happy
Dom

Ronac

I have an s5.

mwpayne

I concur with DOM C. I just did this to my S4 vert and it does indeed work. I'm not totally sure exactly when they're opening, but they for sure don't open until high RMP/load.

Dom_C

why does it matter if you have an s5? the other guy that was asking the question has an s4. you have already stated multiple times that you ahve no 6th port sleevees or anything. good luck cobra r, this is a good mod. have fun
Dom

Cobra_R

Thx i will, hopefully i can do it with out screwing up my car. lol. (seriously)