5th & 6th ports
 

whats the deal with 5&6 ports, i hear lots about them. can someone explain this & how do you know if there actuated. thanks:blush:

The aux port system opens up two more intake ports on the end irons when the engine is under load and above about 3800 RPM. These increase port area as well as extend the intake event quite a bit, even into compression a little. Combined with a tuned intake manifold shaped a bit like a horseshoe, this results in the closing pulse from one rotor forcing air into the opposite rotor. The result is about 2 PSI of positive pressure at the intake ports and far more efficient chamber filling.

To test to make sure the aux ports are functioning, read this:
http://www.aaroncake.net/RX-7/6porttest.htm

Note this only applies to 84 - 92 NA engines.

thanks for the info, i'll try the test to make sure ports are actuating.

well thats great when i get my car back from the tranny shop today i will find out for sure... But by looking at your picture aaron my actuators are non existsent!!!! this sucks :( its an s5 N/A and my air pump is gone too...

Someone deleted them, are there block off plates? You might want to check if you have emissions too just to know because it sort of sounds like previous owner mightve deleted them too

I dont have the car in front of me going to pick it up from the tranny shop in afew hours but.. but theres 2 freaking bolts in the holes were the acuators go! If im remebering correctly

Well usually when people delete there 5th and 6th port actuators they install block off plates over the area where the actuators are supposed to go. They are located on the lower intake manifold. Go to rotary ressurections web site and go to the tech section and look around in there and Im pretty sure it will expain more about the 5th and 6th port actuators.

ya they revolve cylinders in ur irons to open up ur 5th n 6th air ports to give it a lil more punch after 5k rpms on an s5. almost like a power-ban.

No.

The aux. ports function exactly the same on S4s and S5s. At 3800 RPM, the actuators rotate the sleeves to allow air into the additional ports.

S5s also have the VDI system, which shortens intake runner length at 5200 RPM to allow for more top-end torque.

If the air pump is removed on an S5, both of these systems stop working, and the result is a very slow car. More people should read the FSM and training manual before taking things off of their engine.

hence why s5 motors suuuuck. hard to make a nice open engine bay. plus with that stupid smog pump u cant rock a dual alternator pully. and the electronic OMP is just ridiculous. use s4 manifolds and front cover on an s5 keg like i do and ur good to go! on another note. people rip the smog pump and emissions rats nest off for a clean look and others do it cuz they think they get some hp out of it but on the s5 like u said, u lose it!

Huh? A dual alt. pulley is needed when you remove the air pump. There's no reason for it if you have an air pump on the engine, but you could use one if you really wanted to.

S4 intake manifolds are inferior to the S5 version. No VDI = less power. There's a reason people convert TO S5 intake manifolds: http://homepage.mac.com/carldavis/intake.html

the hp gain isnt worth it. u could get more power/weight ratio by getting rid of a ton of junk in the car.

alot of work for such small amounts of hp gain. alot of fabrication and u gotta install a rpm switch for the vdi.

So you don't think 10-15hp on a ~150hp engine is worth it? I think you need to start reading, and stop posting misinformation. I converted my S4 NA engine in this way, and it was easy. A couple hundred bucks in parts for a 10% gain. It sounds like you've done the opposite, and instead made your car slower. Put the stock S5 intake manifold back, put the air pump back, and don't obsess over making a "clean" engine bay. Removing everything you see is a BAD idea.

I guess higher compression, lighter rotors, hardened stat gears, and (on the turbo's at least) stronger irons suck too... I guess I've got all this rotary business all wrong!

I really dont know, bUt i know I want my unclean manifold equipment back especially if im loosing HP!! I just hope this idiot didnt ruin and strip out anything by putting those darn bolts in there!

It's hard to say what was done, but you'll have to pull the LIM off to see. You might find that the port sleeves are still inside, or they might have been tossed with the actuators.

There's a good explanation here, along with pictures from the FSM: http://mazdarx7.iougs.com/intakeair.shtml

Thanks rocket good info there... i got the car back found a couple plug wires coming apart, changing fuel filter and ordered some new ngk wires from napa 27.83 my cost... I need to get ti running better first then tackle the missing stuff...

If they actuators are gone you definitely are loosing power. I dont understand why people get rid of the 5th and 6th ports anway. Even if they arent working it isnt hard to get them to work again or just buy new ones and install them. I think taking your actuators out is a BAD thing on either s4 or s5 engines. Hoepfully all goes well for you

S4 5th and 6th potr
 

Im sorry for getting a little off subject here, but for anyone who has a S4 N/A and wants to straight pipe it, I found that if you straight pipe from the stock manifold and leave your stock Y pipe, then any muffler you want, the 5th and 6th ports will still work like they are supposed to.
Leaving the small stock y pipe with a 2 1/2 or 2/34 inch straight pipe will still create enough back pressure for the secondary ports to work since the S4 cars work on back pressure and the S5 cars work off the air pump. If im not mistaken.
Again sorry for getting off subject a little but I thought it would help someone with an S4 reading this thread.

Thanks for posting this information. I have an S4 and am in the middle of doing an exhaust system replacement as my stock exhaust has rusted to bits. I picked up a racing beat cat bypass and silencer, and I was looking around for a catback to mate to this pipe. So you are saying if I stick with a 2 1/2 or 2 3/4 inch y-pipe then I will still have enough pressure for the 5th and 6th ports to work properly?
What is a good way to test that they are not opening late? I have a minor stumble right at 3800RPM presently, do I just watch for exactly the same stumble later? Or is that stumble not directly linked to the opening of the 5th and 6th ports?

Is it a stumble or a little pick up because there shouldnt be a stumble. If there is a stumble you may have a problem with your TPS. or somethin else. It might be somethin you want to check into, or start a thread about to get more info.

Also you can try the exhaust for your self, Im just tellin what wrkd for me. So if for some reason your ports dont work after the exhaust mod, I heard there is a way to make them work with out back pressure from the exhaust. You have to T off from the air pump or somethin and run a vac. line to the acuator to get the ports operate. Also somethin else you might wanna check into.

Aaron cake and rotary rocket always have the best awnsers and have helped me with a ton of questions Ive had, so there input would be great right now.

To check your ports check this out. www.aaroncake.net/RX-7/6porttest.htm

3800 RPM hesitation is in the FAQ. It's a common issue on S4s (not so much on S5s), and it tends to be related to ECU grounding. Not only is 3800 RPM the aux. port activation point, it's the secondary injector transition point.

Using a pick-up tube to activate the ports on an S4 is hit or miss. The best way in my opinion is to go with a very small pipe coming off of a header, straight pipe, etc... Larger diameter tubing will decrease pressure.

I've also detailed the RPM switch method here: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/activating-aux-ports-vdi-rpm-switches-907824/. For the aux. port actuators alone, it can be done for ~$60.

Rotary rocket your the man,

and I dont know what this forum would do without people like you. That is a good idea about the header and small pipe straight pipe, what size pipe coming off the header and can you recall what diameter is the factory y pipe for a s4 n/a.

Thanks alot for all the info.

Do you mean split air pipe? If so, that's about 1/2", but its primary use is to feed air to the cat. I'd go smaller if the pipe is intended for just the aux. port actuators; maybe 1/4" or 5/16".