I've Seen People Say They Did A Stock Airbox Mod But Now That I'm Looking For It Again I Can't Find Any. Well Except For One But It Doesn't Say Much. I Want To Do A Stock Airbox Mod So If Anyone Whos Done It, Can You Explain To Me What And How You Did It, Please. If It Helps I Have An Stock 86 N/a. I'll Be On Later Because I Got To Go. Thanks A Lot.

 

I don't think anyone mods the stock airbox...

Most people put on a cone filter (in place of the stock airbox). The stock airbox is very restrictive, especially in comparison to this. Make sure to make a heat shield though.

 

you could drill large holes in the top of it

 

NZConvertable has done this mod on his car. I believe he basically just removed the internal baffles. He may have also drilled holes in the top as well.

 

just drill holes:

 

Just get a cold air intake ... drilling holes does nothing in actuallity except give you warm engine bay temperature air, which is not what you want anyways. If it was as simple as drilling holes in a stock airbox then cold air intakes wouldn't even exist.

 

There is no longer such thing as an off the shelf cold air intake for the FC.

It has actually been shown that adding a cone filter (which many un-informed people call a cold air intake) with no cold air box that keeps the majority of engine compartment air out of the intake, will lower HP by about 5 over even a stock un modified air box.

If you can't afford to build a true cold air intake, or have a cold air box, drilling the air box for better flow is a much better modification than a cone filter.

 

Nope, not me. My car lost its airbox long before I got it. I think you're thinking of Icemark.

Personally I'd never bother doing this anyway. I can't see it making all that much difference and any extra air is going to be hot underbonnet air.

 

So Icemark, Are These Pics Off Of Your Car? Do You Feel Any Difference? Thanks For Showing Me, This Is What I Wanted See, Stuff Like This. I Wanted Pics To Get A Better Visual. Do You Know Of Any Other Methods?

 

Stop typing in capitals!

 

Mine is only that way at emissions testing time. the rest of the time my intake is an oversized cone with cold air box

 

sorry its a habit of mine typing in caps. But is there a difference between that and stock?

 

has anyone else done this or has thier own idea/method/way?

 

i like the stock airbox

 

I just cut out the whole piece that has the Mazda sticker on it and dropped in a K&N. Drill one large hole so you can get a jig saw blade in there and trace the edge of the sticker. worked great. Then i discarded all the snorkel stuff.

 

So now you have the hot air disadvantages of an exposed pod filter and the airflow restriction of the lower half of the airbox with it's poorly shaped AFM entry. Best of both worlds...

 

My 90 vert had this 'mod' when i got it. I removed the whole airbox and installed a cone (hot air) intake. I could feel the difference, but it wasn't a good difference. The power definately was lower. I then reinstalled the stock airbox including the snorkle and confirmed that the power was better than with the cone. Good old butt dyno.

To find out what was going on, I clipped a digital temperature probe from one of those indoor outdoor thermometers to the center of the air filter. Now I could compare the temp of the outdoor air with the temp of the air the engine was breathing. Did I mention that the top on my vert was down? It is always down unless it is raining. I drove the car around on an 80 degree spring day. At a stoplight idleing and up to about 20 mph the probe was reading nothing but hot engine bay air. After the car heated completly up, the intake air was at 150-170 *F. Bad, very bad. When the car got moving above about 20mph the temp began droppping. At 50 mph and above it was only a couple of degrees higher than the outside temp. I guess that the ram air on the intake combined with the vacuum created by the undercar tray pull enough air into the box and also out of the engine bay to allow the engine to breathe cool air.

So, I screwed a piece of aluminum flashiing over the box opening to seal off the hot air at low speeds. Now I can feel the restriction in the upper rpm ranges, but my baby is breathing cool air all the time.

Bottom line, no way would I allow my car to breath hot engine bay air with a cone. And think about this: 170 * air before boost on an 80* day???? Boost + heat=bad things, man. You turbo guys talk about heat soaking your IC; maybe this is where the heat comes from if you are using a cone filter. If you have a boosted car, you should look long and hard at this issue.

 

well i don't have turbo so i don't have to worry about boost. so i guess it's not really worth it, unless i do the cold box, right?

 

well...if your really creative and have a spare FMIC...

 

i drilled 1" spade bit in the front only and then removed baffles and smoothed it out as much as possible and it seems to work fine. I also have a headlight cover vent in the works not on yet though

 

The reason the stock airbox works moderately well is because it takes cooler air from infront of the rad via the snorkle. But in order to do this, the stock airbox is sealed to create a suction. Cutting the top "Mazda" emblem out of the box or drilling holes in the top of the box means that no air is being sucked through the snorkle. ZERO air is forced into the snorkle, so any air that comes into your engine after this mod will be warm underhood air.

If you want to modify the stock airbox, then cut out the baffles INSIDE the box. If you comprimize the selaed nature of the box top/snorkle set up, you are going to get less - not more power.

If you don't have the time/money/patience to install a proper cold air box/intake setup, then leave the stock one alone. Of all the airboxes I've seen on this site, precious few give any advantage over the stock setup.

 

No, if you do a few holes as outlined in my picture, you increase flow, without the compromise of a large open section.

This can be easily proved by simply using a stock white air filter, and watching the air flow patterns left by the filter actually working.

If the filter box indeed need to be sealed for the snorkle to work, then you would loose all function of the snorkle with the minor holes.

In addition if you looked at the flow patterns under the hood itself, the snorkle will provide cooler air flow even with the air box removed entirly. See with a functioning under and over radiator panels, the area just behind the bumper (where the snorkly feeds from) happens to be a high pressure area at speeds above 45MPH, while the engine compartment is a lower pressure area.

 

so if i'm getting it right the snorkle still gets cold air through due to the high pressure, above 45MPH, even if it wasn't conected to the airbox itself, right?icemark what kind of difference did your get?

 

As with any air filter change, the results are more a percentage... 2% to 3% is normal for a cone filter (that is at least 5"x 6"dia ) w/ cold air box and 1% to 2% for a tweaked air box with a good filter like a K&N or Ramair.

Of course those numbers drop pretty radically fast if the air box is modified badly or that there is not a cold air box on a warm day.

and your bump has been deleted. Bumps are forbidden here in the 2nd gen technical section

 

oh i didn't know that it was forbidden. sorry. how come? well i guess it doesn't matter, atleast i know now. thanks. so your mod improved rather than drop, or vise versa? maybe i should just to see how to make a cold box.