Ok, I got bored tonight. This has helped on other cars, but who knows with the RX8.

I'm not saying much about the mod yet. Read and discuss:

http://rx8.swankmonkey.com/airbox/

How does the car feel after the mod? More eager?

But...a basic question from a non-tech guy first - Can someone explain why there is a need for the screens? After all, the air is already filtered at that stage.

it may sound silly, but it's to straighten the airflow before it reaches the MAF sensor. Gets a better reading that way.

Originally posted by SpreeGuy
it may sound silly, but it's to straighten the airflow before it reaches the MAF sensor. Gets a better reading that way.

Actually, that is correct in most cases, but our maf is more like a fine mesh, so it would possibly disrupt airflow or create some turbulence over the maf wire.

I wonder what it looks like in the FD?

So far, so good, but I'm going to give it a few days for the ecu to adapt, then maybe take the second one out.

No MAF in the FD! Speed density system....

jds

i dont now if this would affect anything, but is it louder than before, or just the same?



andrew

Sounds about the same. Hard to tell with the windows up.

OK, I just tried this mod for myself. I removed both mesh screens - not just the front one. I've just returned from a 30 minute test flight. How did it go?

At this stage, I have to say that I didn't really notice much difference. The engine runs fine and power feels the same. It's certainly no worse than before. Is it any faster though? Maybe. There might be an extra hp or two, but my butt dyno didn't sense any great leap in performance.

Noise from the intake is the same - no quieter no louder. I'm going to leave the screens out for at least a few days anyway just to see if the ECU learns any new tricks.

I pretty much followed the instructions, with the exception that I didn't do an ECU or DSC reset afterwards. I figure it's a learning ECU anyway, so let it learn!

Theoretically it should do something. More airflow is more airflow. It's just that damn messed up factory ecu that will effect whether it works better or not. I'm impressed to see the nice aero flare inside the airbox to help with turbulence. That's a first for manufacturers.

DGW, glad you tried it too!

Butt dyno says maybe a tad more up high, but although the ecu is "learning" it can take a while if your long term fuel trim is set for aggressive (richer) driving.

I think the best bet would be to drive like a grandma for the first 600 miles, then test it.... but who can wait 600 miles to go WOT in this car ;)

Rotarygod, a lot of other manufacturers are using an intake with a velocity stack at the air box now. Is this a first for Mazda?

It's the first that I've seen, at least on a rotary powered Mazda.

Cool! It is very interesting that it's not a perfect circle though:

http://rx8.swankmonkey.com/images/maf/IMGP1692.JPG

I wondered that myself since it does make a difference. Oh well, something is better than nothing. You know, I wonder if I can use a Rockford aeroport flare instead of that? It is the same shape but a full circle. So what that it is designed for speaker boxes. Airflow is airflow.

The aero port flange comes out almost flush (as in the box surface).

This one and others that I have seen tend to wrap around over themselves a little bit.

I'd say close enough, but the aeroport is designed to remove sounds that come from a standard port in a speaker box... and work with airflow going in AND out.

Once again.... close enough ;) ;)

I'm back again. I've been driving around all afternoon, pretty hard too with plenty of WOT. After a good 2-3 hours of driving (about 75km) I've noticed one more thing - no soot.

Before I did the mod I washed my car and cleaned the exhaust pipes. Normally I find that the soot starts to build up again almost straight away. But now, after two hours of aggressive driving, there isn't so much as a speck of soot on the pipes. Nothing! It looks like I cleaned them 2 minutes ago.

Normally 2 hours of WOT would have them covered in black sh*t, but not this time. They are clean as a whistle.

Originally posted by D.G.W.
I'm back again. I've been driving around all afternoon, pretty hard too with plenty of WOT. After a good 2-3 hours of driving (about 75km) I've noticed one more thing - no soot.

Before I did the mod I washed my car and cleaned the exhaust pipes. Normally I find that the soot starts to build up again almost straight away. But now, after two hours of aggressive driving, there isn't so much as a speck of soot on the pipes. Nothing! It looks like I cleaned them 2 minutes ago.

Normally 2 hours of WOT would have them covered in black sh*t, but not this time. They are clean as a whistle. Now that's interesting...

Wow, I just woke up and ran to the garage.

I also washed mine this weekend, and although I didnt' polish.... you can tell that there is really is not any of that black sooty layer that should be there.

Ok, so I did the first screen only..... I'm going to datalog my run into work this morning with the wideband.... won't have results until tonight though!! Then I'll do the second one and see if there's a difference with a/f!

Loosing the soot alone would be worth the mod! Could it be that this simple thing would change the A/F ratio enough to get rid of the soot? And if so, wouldn't the ECU "learn" the new (I assume) slightly reduced intake restriction, and compensate for it so the soot would eventually return? For that matter, why haven't people who have CAIs on their cars be noticing the same reduction in soot?

Could have just never noticed it, like me.

I don't watch the a/f when driving much, that would be unsafe.... but idle when I got to work was around 14.8-15.1. I'll recalibrate at the end of day (sans no lunch driving) and get some results on the way home, too.

This is conjecture only, but...if it is leaning out the mixture, then that must be because the sensor is reading less air, relative to the actual amount of air going by. If it were simply a matter of better flow, the ECU shouldn't even take time to learn anything...it sees X quantity of air, and provides Y quantity of fuel. Assuming the former, i.e. you're fooling the sensor (possibly similar to what the Tornado was doing) I don't think the ECU will relearn anything, unless it "calibrates" the MAF over time by using the O2 sensor, which seems awfully complicated. Also, while this might be a good thing with a stock ECU, what if you were using Canzoomer's mod? It might put you closer to the edge.

jds


Originally posted by Omicron
Loosing the soot alone would be worth the mod! Could it be that this simple thing would change the A/F ratio enough to get rid of the soot? And if so, wouldn't the ECU "learn" the new (I assume) slightly reduced intake restriction, and compensate for it so the soot would eventually return? For that matter, why haven't people who have CAIs on their cars be noticing the same reduction in soot?

What if you were using a simple air fuel (maf) computer to adjust things?

Anyhoo... that's why I'm recalibrating the wideband to verify results.

More to report....

After driving to work and back today (60km) the soot is back. It doesn't appear to be piling up as quickly as it usually does though.

Perhaps in my frenzied drive yesterday I was going so hard that I was spitting flames and burning the evidence?

Perhaps too Omicron is correct about the ECU learning and hence the a/f ratio is slowly returning to normal, along with the soot.

Could very well be!

I'll have to check my tailpipe when I get home late tonight.

I've had my new exhaust on for about a week now, and I just checked the tailpipe tips for soot. Couldn't find any! They are very clean. Now, I am using a Tornado device because I wanted to see if it really did anything as some here have observed. My observations are that it MAY add a tiny bit of HP, but I have no way to measure it -- not enough to matter anyway. Fuel mileage is a smidge better -- increased from an average of 17 mpg to an average of 18 mpg. What I HAVE noticed is that the "rattling marbles" noise at WOT with 87 octane (pump) gas (this is incipient knock, yes?) that I heard when I tried a WOT run before the Tornado is completely gone when I do so now. So if nothing else it allows the use of 87 octane (pump) fuel without getting knock.

I need to check my fuel economy when I fill up tomorrow, but.....


I have 120 miles on the trip odo already. While that's not odd, I should be in the fuel range where the warning light will kick on at this many miles (my driving deserves that!). For some reason, the gauge is just a tick less than half way between 1/2 and 1/4 tank. That is very odd.

This mod is the only thing that I've done... oh and changed the oil for the second time.

Probably snake oil again...... It's probably the engine becoming broken in or my larger oil filter :D

these airbox mods for our cars really don't work. the 6 yeilded about 1-2 HP. and is louder. glad i have my INJEN CAS now.

Call me an old boring fart, but from my experience:

Rule 1: "Don't mess with the MAF"

It is just fooling the computer into beliveing something that is not true. Yes, I know it is a common mod to do on various cars, and with a lot of buggerising around one might get it correct. But the MAF is the most accurate sensor on the car telling the computer how much air the engine is digesting. Fiddling with something is effetcivley putting it out of calibration. If you put a less resticted MAF in AND tell the computer it's calibration - that is the best way.

Just my 2c. I can already see the flames leaping towards me :)

But until we have something better, who am I to argue!

Cheers,
Hymee.

Originally posted by Wildcard
More to report....

After driving to work and back today (60km) the soot is back. It doesn't appear to be piling up as quickly as it usually does though.

Perhaps in my frenzied drive yesterday I was going so hard that I was spitting flames and burning the evidence?

Perhaps too Omicron is correct about the ECU learning and hence the a/f ratio is slowly returning to normal, along with the soot.

that's your best bet! ECU relearns and adjust accordingly. a mod like this might last twice. just reset ECU to keep this up.;) j/k

Us old fart rotarians know that soot as smoot. It's oily soot. The bane of rotary owners. ;)

Originally posted by Hymee
Call me an old boring fart, but from my experience:

Rule 1: "Don't mess with the MAF"

It is just fooling the computer into beliveing something that is not true. Yes, I know it is a common mod to do on various cars, and with a lot of buggerising around one might get it correct. But the MAF is the most accurate sensor on the car telling the computer how much air the engine is digesting. Fiddling with something is effetcivley putting it out of calibration. If you put a less resticted MAF in AND tell the computer it's calibration - that is the best way.

Just my 2c. I can already see the flames leaping towards me :)

But until we have something better, who am I to argue!

Cheers,
Hymee.


I agree. Some who have replaced the airbox and / or screens have experienced rough idle, due in part to the screens being removed. The turbulent airflow cause the rough idle.

Any a/f ratios to report? CJ

Should have some time to log this weekend. That will also ensure that the car has fully adapted, and I can calibrate the wideband in the morning.

Here's some data, finally got the tps and maf hooked up. Just a run back from the store with the car warmed up:


http://rx8.swankmonkey.com/images/af_log5.jpg

Looks like its pulling a 12ish a'f ratio under wot? Any numbers prior to the descreening? CJ

If you have time to compare, I have some other ones prior to de-screening here:

http://rx8.swankmonkey.com/airfuel/

I haven't compared yet, but will be doing so very soon!

Any longer term updates on this?

http://rx8.swankmonkey.com/images/af/af_log7.gif

So, I am curious why you didn't remove the second screen.

Just haven't tried it yet!

Okay, for the love of God; DO NOT TAKE OFF BOTH OF THESE SCREENS! I tried it both ways and reset the ECU each time, giving the ECU some time to relearn some parameters. With just the first screen removed it works great, no change in idle or driveability. Without both, it is horrible. It won't idle for crap, and low end power went into the toilet. The idle would sit there and go up and down as the electrons ran around screaming "THE SCREENS ARE GONE! THE SCREENS ARE GONE!." Bottom line is, do not do this unless you have some way of messing with the ECU. What I want to know is how the intake manufacturers are getting around this? Are the aftermarket pipes the same as the factory pipes? Or are they a bit smaller? Perhaps they are able to have a longer straight section before the MAF. Any information?