looking for some input here. been doing some research and i'm going to lay out what i believe i have learned. what i'm asking is for people to correct me if i've misunderstood something and what is correct, as well as suggestions on more practical, beneficial or reliable options

first off, should i tear down my motor and THEN buy what i need after seeing what i can reinstall/reuse or just buy a total rebuild kit. trying to have as little down time as possible. how much money can be saved by reusing acceptable parts or is it just worth it to do everything (currently at 15x,xxx original miles and know i have at least a failed oil seal)

ok so down to business. Car is an N/A S4 that is street driven but is not a DD and will most likely be doing some drifting. That said i'm planning on a build for some mid-high rpm power, but don't want a total dog down low (tall order i know) for the street use it does see. Car already has pacesetter headers, a 2.5" cat delete mated to a 3" catback and a K&N intake. also have done the emissions removal.

I'm looking into porting and think i have decided on doing a large streetport (probably using pineapple's template) and considering doing a bridge on my aux ports. from reading i have learned i need some type of EMS to get the right fueling, therefore looking into the Rtek7. is this an acceptable setup or should i opt for a smaller port if doing the half-bridge?

I gather that the intake manifold is the major restrictive component. what are my best options? i've read about S5 swaps but it sounds like a tough job, however there is an S5 in my local scrapyard that i can get parts from for a great price

If used i can maintain my S4 TB and ECU, correct?

I can use S5 rotors (if i buy the engine from said car). does that require balancing/other modification or will they be a direct replacement with the benefit of different (higher?) compression

Injectors don't need to be upsized immediately but if done so later on the Rtek will allow for adjustment

I think thats all for now. thanks in advance for any help. trying to learn as much as i can before reaching out

 

I would probably tear down the motor first even if planning to buy the total rebuild kit to find out the condition of the rotor housings. At 15x,xxx miles good chance they are done for.

I'll let someone else cover porting as from what I gather most are opposed to bridging the aux ports.

To use the S5 rotors you need the front counterweight from the S5 and depending on what fly wheel setup you plan to run either the stock S5 flywheel( counterweight is built in) or a S5 rear counterweight from an automatic and the lightweight flywheel of your choice.

 

a total rebuild kit doesn't even cover half of what normally fails in a rotary engine. in fact, master kits are often a bit of overkill with half the kit not even being necessary.

don't bother bridging an n/a 6 port, at best remove the exhaust port sleeves and install turbo ones and port the primaries. the secondaries aren't even worth fiddling with.

the s5 manifold does flow slightly better than the S4 however your ECU cannot control the VDI, so just forget about attempting it.



if your aim is for modification, you should just save your money for a turbo engine and forget putting money into the 6 port block. the n/a engines don't have a lot of room for growth unless you seriously modify the engine for a PP or semi PP and run a real standalone, not an Rtek, and then you wind up with a loud and obnoxiously annoying car to drive.

 

ok so negative on the S5 parts, thats good info thanks.

i really like the idea of the half bridge so i can get the rotary's unique idle. i understand i'm going to quickly hit a wall when it comes to gaining power and further mods but i'm not looking to go crazy with the car. 200whp would be awesome, but if i fall short i'm not gonna lose sleep over it. so with that in mind, would it be better to bridge the primaries and leave secondaries and the aux ports or the other way around? do i bridge the primaries AND secondaries and leave the 5/6 ports untouched? i guess i'm having trouble understanding what constitutes a half bridge vs a full bridge (i assume full is all ports). basically my goal is to get the overlapping idle sound, minimize low end loss (i know there will probably be some) and gain a little mid-high rpm power. also planning on porting the exhaust since i already have a very free flowing system. basically i'm looking to follow judge ito and touge monster. i got a lot of my info and inspiration from here: https://www.rx7club.com/build-thread...ki-fc-1009424/

i understand this is not a highly recommended thing to do but i'm trying to get the info so i know what i'm getting into

is there a way to get the overlap without a bridge? if i don't do a half bridge i am definitely doing a large street port. would earlier opening of the primaries and later closing of the exhaust give me the desired effect?

and on the subject of EMS i'm following that thread until i can afford to get a haltec or megasquirt. if needed i'll clock the AFM for a touch more fuel

 

You can turn your idle fuel way up and get a similar brapping effect.

 

If you are porting just to get a specific idle, then you are wasting your time. Port for your realistic objectives, and not just for sound alone.

If all you want is 200hp, you would be soooooooo much better off doing a T2 swap.

All ports is Full Bridge. There are many posts on this subject, but Rotarygod is very vocal about his distaste for AUX bridge porting.

https://www.rx7club.com/rotary-car-p...bility-221213/
https://www.rx7club.com/2nd-generati...e-port-186562/
https://www.rx7club.com/naturally-as...advice-973937/

You will lose low end power. In a big way. A bridgeport reduces port velocity so much, that it will be a dog. You will have a large increase in power above 6500rpm provided you have enough flow INTO the engine. The stock intake manifold becomes a big restiction where a bridgeport really makes power. Above 8000 rpm. That thread that touge monster posted has multiple replies from many, many people saying that his plan with a stock ecu was not the best idea. He managed to get the car to idle, drive, and presumably operate at WOT. Just because it runs, doesn't mean it runs well. The only way to successfully operate a bridgeport is with a standalone ECU of some kind. Period. The NA ecu just doesn't have the capability of handling the extra airflow efficiently. The NA airflow meter will be a restriction, so it's gotta go. Now the car will not run without it. You're in standalone territory now.

It's not recommended. Get 4 port turbo irons if you must go bridgeport. Get a Racing Beat IDA manifold and run ITB setup with 2x1000cc injectors in the primary position. That way you have enough air coming in and you will be able to make the power you want.

All rotaries have some overlap. Yes, a large streetport and moving the exhaust later will give the sound, but it's almost never recommended to port "up" on the housings. It will cause charge dilution at low speeds and probably surge.

If you can't afford a megasquirt, you can't afford a bridgeport. Clocking the AFM will not be wise. You will spend more time fiddling with a system designed with stock ports, than actually driving the car. Get a MS1, MicroSquirt, or MS2. They are cheap and will accomplish what you need. A microsquirt will run a 13B with ITB's BTW

 

well i can't afford a tII swap or a standalone, hence the questions. also i kinda like the idea of a strong N/A. its easy to make power with a turbo...

i guess i'll just be doing a large streetport. is it possible to go in afterwards and add a bridge once i can get a standalone?

so for exhaust porting do i just open earlier? isn't that counter-productive by shortening the power stroke? or do you balance it between opening and closing?

and i would love to run ITBs but again, that won't be able to happen until funds are there. also, wouldn't ANY standalone run them? or are you just getting at the most cost effective way to be able to properly run it

 

I would suggest if you do any porting to do a street port since you can't afford a standalone. I'd also suggest you buy some porting templates for both the intake and exhaust being new to porting and all.

You could open it back up later and do a bridge since depending on the miles at the time of reopen you could likely reuse the seals on the rotors. You would nee new water seals though.

I think ACR was pointing out the cheapest way. There are others that would run ITB's just fine.

On the S5 manifolds you could still use it but since like Rotary Evolution mentioned your ECU can't control the VDI you'd have to wire it to the high rpm position. You may only see any gains above 5500rpm where it opens. If all your emissions are removed now are your aux ports still functional?

 

I still feel like you are getting in over your head and are not approaching this realistically. A rebuild kit with all of the pieces is close to $1000 or more. As RotaryResurrection said above, not all pieces are needed, but that is a good starting point for rebuild budget.

The apex seals in your engine are likely 3 piece seals. They should not be reused, so new apex seals are needed. An engine closing kit is close to $600 or more. You would still want to replace all gaskets on the manifolds and front cover, so that's another $200-400 depending on source.

Without getting into fluids and tools needed (if you don't have them) we are already at $1000.

Unless you know exactly what you are doing, get porting templates. Racing Beat, Mazdatrix, and Pineapple all sell them. They are rather cheap and reusable. There is not an existing 6 port bridgeport template that I'm aware of purchase. That means you have to map and cut your own ports.

You have not told us your budget, so we have no idea of what you mean by "can't afford. I **** you not. You can get a Megasquirt I kit and 10ft harness for less than $300.

MegaSquirt I Kits Megasquirt Kits / Assembled Engine Management Systems, Wideband o2 Sensor Systems and tuning products - DIYAutoTune.com

Any porting beyond streetport requires a standalone or SAFC of some kind.

You can I suppose, but there is no point in tearing it back down to add ports that will substantially lower low end power. By that I mean below 5000rpm. And MAYBE a 10-20% increase above 7000rpm.

That's why you get a template. Power is gained by opening earlier, to an extent as dictated by the template. The combustion process is done earlier than the stock port opening. (I know that rotaries afterburn, but useable combustion is done)

Almost any standalone can run ANY engine is almost ANY induction strategy, so yes. ITB is just a throttle body and manifold setup. The most cost effective way is to do a streetport. Not a large or raceport. The S4 NA center iron doesnt have alot of room to port before you hit coolant passages. The secondaries are already very large with a HUGE port area. Removing the AUX sleeves and doing a small amount of porting can help, but at above 7000rpm, which is above the RPM that the S4 intake is effective. The S5 intake is a better option. Just remove the sleeves and rods for the AUX ports, wire the VDI open, and that should be good for about 170-180 hp. Low end torque suffers on any 13B na that is ported and is missing the AUX functionality.

Just look at what Dak has built in his sig.

'89GTUs
Turbo rotor housings, Streetport, lightweight steel flywheel, intake, & exhaust.
No airpump, removed 6port sleeves & rods, wired VDI.

Sounds like a route you can go. Also, spend some time here doing research


Naturally Aspirated Performance Forum - RX7Club.com

 

yes my aux ports are still functioning. i had the backpressure tube welded into my headers at the collector and i didn't notice any power loss. emissions were removed before i even got my exhaust so i feel like i would have noticed if they stopped working.

i was already planning on using pineapple racing templates (i mentioned that). i'm competent with tools and that nature of work, but i wouldn't risk going free hand regardless.

as far as bridging later, i was talking about when i need another rebuild, not in a few months if i get funding. and on the topic of budget, my plan is basically get a credit card to pay for the needed things. i've been meaning to get one for backup anyway so this gives me a good excuse. i'm trying to keep cost to around $1500, and i already knew i was gonna hit the $1000 mark for the kit alone. i need a clutch as well (might do flywheel too but that cuts into budget more and i would need the proper counterweight)

thanks for the link to the MS. i'd been there before and was looking around the page, but i wasn't really considering the MS1 because its outdated. but if it can handle running a bridge and later on possibly ITBs then its certainly an option. also thanks for the NA link...i honestly never knew about it -.-

i have been doing a ton of reading a feel like i have a decent grasp on whats going on, i was just looking for some feedback from the experienced guys. i'm not new to working on cars by any means, but it is my first rotary so i'm being more cautious than usual

 

I had asked because if they weren't and you had them wired open then you wouldn't really lose anything going the S5 manifolds and wiring everything to the high rpm position. Since yours are working idk if the gain on the top end is worth the loss below 3800rpm. Someone who has made the switch would have to answer that since all I've ever had was my S5.

I must've missed the part about the Pineapple Racing templates. Those are what I used on mine. I used the EP2 exhaust. I have been happy with my results.

 

the days of getting $3000+ credit cards just for the hell of it is gone. i have good credit and i have to start out with $500 on new cards and let them accrue more credit over time.

 

Another rebuild? Like in another 200K? That's a long time to wait for the next stage of a project. Guess though it depends on how much you drive.

Others have basically covered it but I'm going to offer my 2 cents after building a lot of bridgeported cars (4 and 6 port) and having an aux bridge of my own since....2006 or so.

You can't cheat a Bridgeport. Any sort of eyebrow you cut means basically 100% overlap. So just bridging the aux isn't going to help in that regard. And just bridging the aux, IN AN NA APPLICATION, is basically pointless. It will result in a large decrease of low RPM torque due to the overlap, but won't add much flow up top. I'd be surprised if it makes any more power than a street port. So this basically makes the idea of aux bridgeports with functional sleeves sort of pointless.

One thing that doesn't seem to come up as often with bridgeports is the fact that fuel economy is terrible. Do you want a car that gets 8 - 10 MPG around town? To put that into perspective, it means filling up every 120 miles of city driving. A Bridgeport with it's ambiguous vacuum signal is also much more difficult to tune. Can you toss a stock ECU at it and have the car run? Sure. Does it run anything close to acceptable in my terms of "acceptable"? Nope, not a chance. A standalone is basically required to compensate for the wildly different fuel and timing requirements compared to less aggressive ports.

In an NA application, in order to get decent power out of a proper bridge, airflow is critical. Which means loud.

Bridgeports have their place, and can be fun. But this isn't it.

Honestly with a properly tuned standalone and minimal porting to the NA irons, you'll have your best compromise between power and drivability.

 

ok thanks everyone for chiming in and not just totally destroying me haha. like i said this is not a daily driver by any means, but i use it as often as possible just because i enjoy driving it. it already has **** gas mileage (i guesstimate around 14mpg). and really the purpose of the build is so i can go drift it (if anyone has been in my build thread), so mid-high rpm power is going to be most beneficial anyways. i guess what i was looking at was a bridge on the secondaries rather than the aux ports...i don't know what difference that would make, but until i have a standalone i guess i should just avoid it altogether. i don't see why i cant rework things when i get bored of it and have the money or find another engine to build differently

and Aaron, yeah i suppose that would be a long time to wait haha. the car is already loud thanks to my exhaust setup so i don't know how much worse it could really get. driving through the city the sound just reverbs off of everything. its almost embarrassing but then i remember what i'm driving and just laugh

 

my car is plenty quiet, but then again it is a turbo and they can get away with it easier.