hondasr4kids

well I'm thinking removing the screen in the horn and the "walls" along with disabling the flap at the intake hose in the bumper, this should give me the same as my REVi intake which is very similar in design to the stock air box with this mod exept the filter which I'm looking at on how to put a cone filter or just put a drop in K&N one.

BoosTED

iTrader: (2)

I have the K&N drop in and I noticed a difference when I replaced the stock. Not huge but there.

Arkimidies

One thing that might smooth out the airflow from the rubber hose is replacing it with a solid piece of pipe, either high heat PVC or stainless steel. This was a popular mod for the ZX2 known as the Keman Intake Mod, there were some other things to the mod but it really does not apply in this case.

hondasr4kids

I was thinking about that too. Let see what my mind gets too.

KYLiquid

wow old thread....

anyway, just so eveyone knows, you can remove and alter the stock airbox all you want, your going to get a louder intake sound, and MABY 1-3 hp at the very top of the power band 6000RPM + , and thats about it.

That said I did pull the intake 'dividers' out when I changed the air filter, because I actualy broke one the fist time I took the damn air box out to check the air filter (oops, lol) I did notice a bit more noise, but other than that....everything was the same, idle, power, response all stock so the good news is no decrease in performance.

Later, about a month ago, my VFAD was damaged when the nose of my car was bumped....i went ahead and got the mazdaspeed bumper and decided to pull the VFAD off completly, since I had the bumper off, and it was broken. Again, there is more sound, esp when I go WOT in 3, 4, 5 at around 4k rpm. The sound is nice, i like it....but idle, power, response, ect....all stock, so its good that nothing was hurt by the mod...but at the end of the day, if a little more sound is what your after, go for it...if your looking for power, dont waste the time.

I plan to get the revi, so the VFAD would have been pulled anyway, now I dont have to remove my bumper when I get the intake.

hondasr4kids

well i have the REVi installed and I didn't notice no power gains either. I did notice better responce. I figure it was because the VFAD was removed. If you power shift with the VFAD installed you notice that the car will take a second to jump back on. That because the VFAD. So I was thinking of disabeling it. I know I'm not going to get more HP # but the stock box and the REVi are very similar in design exept for the filter itself.

KYLiquid

well they are similar, racing beat basicaly took the mazda design and make it better (actualy not better so much as didnt compromise like mazda did) rather than a flat panel filter, its a round filter, with a cone on the end to direct airflow to the filter media. Also the bell on the intake trumpet is a complete bell, mazda had to cut the bottom of the bell off to make it clear the flat panel filter. The mazda design is very good, aside from the ecu, its one of the reasons that aftermarket intakes dont give much gain, cause the stock system is really good.

The few things racing beat could improve on they did. From the dyno's ive seen of the intake and looking at the intake in person, it doesnt add a lot of power, just a few, but it smooths/maximizes the airflow at all rpm ranges, so you get a nice (be it small) bump in the curve from low to high rpm. I think its a great intake, there are a few others, that are similar form major tuning houses in japan, but the cost of them isnt worth the differences (IMO) so I will stick with the revi w/ ram air. I think the car has great performance already, so even a little improvement in power would be cool, but I dont 'need' it to be happy.

My goal with this car, as far as looks, suspension, power mods...ect is to take what mazda had planed and make it better : This car is all about response, pin-point control and feedback....excaly the things I want.

That said the mods of removing the VFAD and air 'dividers' does change the sound, and smooth out the idle, maby I just didnt notice it, but I could also make the response better, and smooth the feel as the ports open and close thru the rpm range.

max5roadster

Just got around to doing this yesterday. I took out the dividers and the air horn tube/1st MAF screen. I noticed no change in my idle, but the intake was slightly louder. I was admittedly sceptical, but to my suprise I did notice a slight bump in acceleration in the mid-upper RPMS. I have a K&N cone filter with a built in velocity stack on the way which will replace the stock filter, attaching at the air trumpet tube. I am pleased by the results so far.

Crazy Rx-8 Driver

k noob question... what is VFAD ??? damn acronyms lol

max5roadster

OK, I finnally got around to putting my new K&N X-Stream Filter in to my gutted airbox last night. My initial impressions are really not much. But, whne I first removed the dividers and trumpet, I did not really notice much;however, as I continued to drive the car, it seemed to become faster and more responsive I am hoping that the same will happen here. My only point of concern with my current setup is the filter inlet size. I want the kind with the velocity stack built in and they only made one in the proper size with a 3" inlet, but the trumpet is 3.5". I mounted the filter by inserting a 3" colar into the filter mounting end and then squeezing the filter end into the 3.5" opening. I am concerned that I may be hampering flow at the top, but am not familiar enough with the CFM requirements of our engine @7-9.3K. I may try a 3.5" mount without the velocity stack (just a regular cone filter) just to compare. On a side note, I left the bottom of the airbox off with the filter exposed jjst to see how loud it was... LOUD!!! It was louder than most exhaust systems! The entire car just resonates. Once I got home and cleaned the blood from my ears, I took a few very quick pics. I will share more later. Any thoguhts on flow restriction with a 3" opening? I have not removed the VFAD, but will soon (New carbon fiber hood coming, too-thanks to a misguided tree limb.)

rotarygod

A 3" opening is not a restriction. The throttlebody is 3" but it also has a butterfly valve in the airstream which makes it flow a little less than a 3" pipe even when fully open. A 3" pipe may flow worse than a 3.5" pipe but if both sizes flow more than another part of the intake, their actual numbers are irrelevant as they obviously flow the required amount. Anything extra is just that, extra.

max5roadster

Thanks RG. I seem to remeber that now that you mention it, but I don't know why it ididn't occur to me earlier...

G8rboy

I ended up doing something similar last winter with an extra airbox... I was able to find a 3.5" opening oval filter, but not this new style with a built in velocity stack. It worked good, but I felt it was choking on the higher RPM's and not pulling hard all the way to 9k. I don't think your 3" opening is a bottleneck as the throttle body opening is also 3"... I think my problem was the filter shape and it taking up too much of the inside of the box.


I ended up scrapping the K&N project after getting higher CFM#'s from my CanScan tool with the Green performance drop-in filter, so I used that for my custom box instead. Now that the weather is nice and cold, I may try that trick with the K&N and no bottom box to see what it sounds like : ).

max5roadster

Thanks for the feed back. I just can't tell if it is or is not making more than the stock filter. From the lools, I'd say it has too flow more. It also has the top of the filter as an open filter section as well. Just hard to say. I step on it at 3-4 and the car tires just spin the whole way it seems, but it is also cold and these tires suck donkey in the cold. It did it with the stockflter too, but maybe not to this extent. I need a canscan...
Santa, where are you?

mtnryan

well I have to say thanks for the mod..I did mine today and am pretty impressed I for sure can feel and hear a difference and looking in that box you kinda have to wonder how did this car get air in the first place haha..and way mine did awesome and thanks for the mod

Slidin8

my JDM RX8 didnt have the walls in the airbox at all, and we have 247hp,

i know removing the walls isnt gonna give you an extra 9hp, but it could help

Brettus

iTrader: (2)

247 ! how awesome !

Slidin8

Please do correct me if i'm wrong

Brettus

iTrader: (2)

well it's actually more like 220hp .... if you are lucky . Which translates to around 175-180whp.

Slidin8

who knows, my motor pulls pretty hard, im happy for now

off subject brett but are u gonna buy that top mount turbo kit that rx7heaven are selling?

TeamRX8

iTrader: (25)

it will do more to install some cool JDM bumper sticker, plus you will be the envy of all teh other n00bs ...

Brettus

iTrader: (2)

nah . Top mounts with big turbos are less responsive than what I have and it's rare for one to make any more power than mine anyway.

nycgps

iTrader: (1)

what a Genius way of modding ! oh man how do I miss this? Dannnng I am gonna do this to my car too I need that 247 so bad ! I can't beat that Geo Metro around da Block !

Slidin8

and my favorite

Slidin8

I was merely pointing out that the jap spec rx8s didnt have the walls, and had the hp rating stated by mazda was higher.

obviously removing the intake walls isnt gonna give you 9hp, i never said it would.