RobbyP33

So in school next year I gotta rebuild two motors so I'm thinking why not port the motor in my RX-7 since its getting pulled anyway right? I know alot of people are dont like the idea of a bridgeport on an S4 motor but I've seen it done and they sound nice so why not? Im just making a parts list and just want some input on what I should buy. The only mods on the car that would effect HP is a K&N filter and a full Racing Beat Exhaust.

So heres my list so far, its vague but thats why I'm asking for help..

Apex seals (not sure brand is best or not)
Possibly bigger injectors (not sure if ill go all around or just for the secondaries)
Maybe an aftermarket ECU (I see them run on alot of NA cars but not really sure if they give the power gain of a boosted car.

I know it's not much but it's a start right?

Pettersen

iTrader: (1)

I would get stock mazda seals, they are good. I doub't many of the other companys making seals have gone thru the same kind of R&D that mazda did. They cost more, but the cost of a rebuild due to a bad seal is much more than that difference.

Stock injectors should probably be enough, if you plan to upgrade and are going to go with aftermarket ecu(wich you probably should on a BP) i would just get two modern 1000cc injectors (Injector dynamics or bosch or similar), they hold idle fine and they should be able to supply all the fuel your NA 2 rotor will ever need.

You need an aftermarket ecu if you are going to do any serious tuning, only exception is if your stock ecu can be hacked and you can change the map on that or if you are running a carb. If you want turbo gains, you need a turbo.

And in case you are wondering what aftermarket ecu is best:
The best aftermarket ecu, without a single doubt, is the one your local tuner know how to use properly.

23Racer

I agree with everything said above and I use a pair of stock S4 NA injectors in my primary rail and a pair of S4 TII Injectors in my outer Throttle bodies and they have no problems supplying as much fuel as needed plus they idle like a stock motor. I was actually able to tune out most of the BP lope with a tuneable ecu.

Also remember that a BP really only shows its strength at higher rpm, so you need to look at the stuff that makes the motor survive at higher rpm.

Eric

RobbyP33

Should I get a different housings, rotors, or e-shaft? Or should I just stick with the S4 ones? Should I remove the actuators that make the 6 ports function? Or will they function with the BP?

Sorry for all the questions, this is my first build thats more than just bolt-ons haha.

RobbyP33

Also, the motor has about 153K so I assume its been rebuilt once. It also has low compression numbers (no the worst but its sure not good). So should I buy one of those rebuild kits with all the gaskets and such or just the apex seals. I know the gaskets don't have much to do with compression, just asking if I should buy it.

Pettersen

iTrader: (1)

I would go with all new seals, gaskets and O-rings.
Just keep your rotors, housings and e shaft as long as they are within spec.

I would ditch the stock intake all together, and go with something that is capable of giving the engine the air flow it needs at high rpm.

peejay

Why? 153k was a good life for a FC turbo engine. N/As would get 200-300k before they finally just plain wore out if the coolant lands didn't crack out first. I've bought core FC N/A engines with more miles that looked nearly perfect inside except for the usual rotor housing center ridge developing and of course the useless side housings.

RobbyP33

Something like the K&N Filtercharger? Also, should I keep the stock oil injection system or run premix?

peejay

INTAKE, not air filter.

RobbyP33

something like this?

http://www.summitracing.com/parts/ap...FdcXHwodyPYHcA

peejay

No no no no. That is an air filter.

An intake:

RobbyP33

Where do I buy one of those? Does it basically delete the big black hose from the intake manifold? If it does, then what about the airflow meter?

Pettersen

iTrader: (1)

It deletes the whole stock intake, since it's a completely new one, but the one on the picture has a carb, and you would want one with throttle bodys and injectors (EFI).
You get shorter runners (pipes from the throttle body to the engine intake ports) wich are good for high rpm application.

And just to make it clear, pod filters or whatever usually gives you less power, unless you build a proper box for it and get the engine mapped, wich will probably result in the same hp you had before or a not noticable increase, IMO pod filters are only good for getting more engine sound and ease of install (wich is why i use them, just know that they won't give you a 10% hp increase).

If you get an aftermarket ecu you will most likely not use the AFM anyway

You should maby just forget about the intake, and keep your stock one for now. And just upgrade the intake later, when you have a better understanding of things. Not trying to put you down or anything, it just seems like you are new to this, and need to read up on a thing or two Overhauling and porting the engine properly should be enough challenge to start with.

I know mazdatrix, racing beat and atkins rotary sells similar intakes. Also rotaryworks sells on ebay. But if you are on a budget(or don't want to pay more than you need to), just try to find something used on the parts for sale part of this forum.

peejay

Yeah, don't need to worry about the airflow meter, you're going to be trash-binning that anyway.

lastphaseofthis

iTrader: (8)

nothing will ever give that besides a booster. super or turbo. you can gain better over ur current, but anything you do to an N/a will gain more if you had a turbo car. accept that and you'll be ok.
n/a is 5 times as expensive to get over 200, 10x to get over 300, and 20x to get over 400.

peejay

N/A is way cheaper than turbo... present problems notwithstanding, you don't have to upgrade your clutch or transmission or rearend since you won't be making significantly more torque. The cooling system loads are also a lot lower.

Go with a turbo, you need to upgrade ALL of that, or get used to changing parts when they break. Or never use the power, at which point why even bother?

lastphaseofthis

iTrader: (8)

oh pee jay... HIS comparision was between a "boosted car" which i interpreted as stock turbo car. not talking about converting it to turbo.


you can see more gains on a turbo car just upgrading the ecu( and therefore likely turning up the boost) then if you were to just upgrade the ecu on an n/a car.

my point was simply don't bother comparing your n/a build to a turbo rx7, you will be let down again and again, its not going to be nearly as fast.

peejay

I'm assuming he has a S4 N/A already.

23Racer

Aren't you guys more worried that he wants to rebuild his motor and he cant tell the difference between an Intake and an Air Filter or air tube? Rebuilding these motors is not intuitive and I don't think an average Auto Shop Teacher is going to be much help. More power to the OP if he can do this, but some time reading up on it and watching video of rotary engine rebuilds is necessary before you even decide to crack the keg.

Eric

peejay

A little, but I'm in a forgiving mood because there have been two decades of ricer idiots calling air filters "intakes". And ignorance is just the precursor to learning.

Pettersen

iTrader: (1)

It's not difficult either, best way is learning by doing. But watching a rebuild video first doesn't hurt either, lots of useful info/tips in those.

j9fd3s

iTrader: (3)

when i was a kid we had to watch a rebuild book, and we thought we were lucky to have that!

RobbyP33

Alright, first off I was saying that I didnt think an upgraded ECU on a N/A would give you as much power as an upgraded ECU on a turbo car. I know that it would be crazy to think that those two are on the same level. I just like N/A because of no turbo lag, my daily is a turbo and it kind of gets annoying. I know that my engines teacher hasn't worked on a rotary so im basically on my own. I plan on watching some videos and getting some scrap housings to practice on. This post is basically me gathering a parts list for the build. I know I dont know too about porting but ive been wanting to learn.

btw: if you guys got some good videos the explain the process feel free to share them

Pettersen

iTrader: (1)

I think the Atkins rotary rebuild video is good, if you watch that and have a workshop manual (for all the torque specs), that should cover most of what you need to know to rebuild a rotary engine. There are other rebuild videos out there, just google it.

As for porting, you should use the search engine on this forum, there are alot of threads on the topic. Wouldn't hurt to check google for that too.

Anyway, here are some useful links.
Mazda Rotary Instructional Rebuild DVD (ARE56)
https://www.mazdatrix.com/faq/porting.htm

RobbyP33

I have access to pro demand and all data, shouldn't that have all the torque specs too? I'll be sure to check those links out too!