I’m looking for a filter for my stock air box that is going to give me the most results does anyone have any suggestions, the car is all stock except for a new exhaust.

 

anything is fine, the filter isn't the restriction

 

then what is?

 

The air flow meter.

 

i’m sorry i don’t fully understand, so what does the airflow meter restrict? and how can i unrestrict it?

 

The air flow meter is an old school flapper door (S4) or cone style (S5) depending on model year. This is a large restriction in the intake compared to modern mass airflow sensors. You would need a standalone ECU to ditch the stock air flow meter. Clearly, that has varying degrees of cost based on which ECU, if you do the work yourself, do you pay for tuning, etc.

 

alright i sorta understand now, i have an S5 and i have been looking at a lot of posts seeing if i should get a cold air intake or something instead of the stock box but everyone made it seem like i should keep the stock box and then throw in a new performance filter, i just started to work on the car as it is my first project car so i’m still learning a lot and i don’t have the tools for what your talking about, so would you just recommend some sort of universal cold air intake ram or something like that then instead? would that be easier or not?

 

You could put on a universal cone filter, but then it's sucking in hot air from around the engine. Mazda actually did a pretty good job of sourcing ambient air on the intake. I'd keep the stock air box, put a new filter in, and worry about other things.

Normally aspirated or turbo S5?

 

it’s an NA i’m saving up for a turbo II, what do you think would give more performance stock air box with a new filter or a universal cone filter, or are they about the same and should i just try something else for performance?

 

I'd stick with the stock air box. If you're looking for quick power gains, exhaust is a better place to start. With the N/A, I wouldn't even worry about power after that. Make sure everything else is taken care of - any worn suspension bushings? How are the old shocks - are they blown? My idea of a perfect N/A is a nice sounding exhaust, and a whole bunch of handling mods. Your wants may be different.

 

you i guess your right and i’m replacing all the bushings soon, the shocks are surprisingly good, i was thinking of possibly throwing a sway bar on or something like that for handling, and well i just got my exhaust done on it and it sounds good, but i guess for the things i want to do to it my best bet would be getting a turbo II or getting a parts car without an engine and LS swap it or something like that but thank you for your help, i guess i should just focus on suspension and then get some nice rims and tires.

 

since its Air Box->Filter-> AFM->hose-> engine, and the restriction is the AFM there isn't much to be gained by changing the air-box or filter. the box and filter are the same for the turbo cars, which were 200hp, so for the 160hp na, its ok..

you do want a clean filter for sure.

for a fun street car, on a budget i do the following;
1. you want a fresh tuneup, filters, spark plugs, oils etc. the car is not picky about what oil you use, but it does like fresh oil.
1a. if you didn't replace the spark plug wires, i measure the resistance, new is about 8k ohms, upper limit is 16k, the higher the resistance the less ignition power you have.
1b i like to change the filter in the tank Denso 952-0043 is the factory part

2. make sure all the valves on the intake move, you can push them by hand, they should all move. if stuck it needs investigating

3. i then move on to the chassis, you want to look it over and make sure there isn't anything too bad. i like to rotate the strut tops, and get as much negative camber and caster as i can. and if you can set the toe in, zero toe in the front is great, and i like a little toe in the rear.
3a. your transmission mounts are bad...
3b. lube the locks and hinges

4. if the shifter is sloppy, replace the bushings. i also check the clutch and brake free-play too.
5. clean the windows, its a placebo effect, but clean windows make the car run better.

6. Exhaust. this makes the biggest difference. Racing beat makes the easy stuff. if you have a street car the downpipe->cat-> cat back is an improvement, quiet and potentially passes emissions.

 

oh and all the manuals are here Foxed.ca - Mazda RX-7 Manuals

 

The guys above really covered the meat and potatoes of the stock inlet system versus an aftermarket cone filter inlet. I use a standard Wix brand air filter in my 10AE. The quality is nice and it filters well.