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I must be getting old... :-) DIY 2012 intake modification

42K views 108 replies 29 participants last post by  TORQUERULES 
#1 ·
I LOVE my Mustang being obnoxiously loud, but of course it isn't driven anywhere close to daily. I had a 2001 Zx3 and of course a lot of modifications because it was fun at the time. Now that is sort of old. Let's face it... a loud 4cyl kinda sucks (of course that is just my opinion).

There has been a lot of talk about a better air induction set-up on the new Focus and I have to say I am impressed with Steeda's gains with their kit, and I love the ingenuity of some of our members in doing everything from a 3 inch hose providing extra air from the bumper to taking the air cleaner lid off. But, and this may be me getting old, the noise from an open filter on this engine is obnoxious. The ONLY way it sounds good is at WOT and that is not where I spend most of my time in the Focus. This is a great breathing engine and it likes to ingest air, but unless there is a louder exhaust (and it would have to be decently loud) to offset the intake, then it is just nasty. Not even a good tone down low. Just a sick and loud boggy sound. Yuck. I want to eventually put something like the FS Stealth exhaust on my car because they have a nice deep tone, but it won't really be enough to overcome the intake. I would love to hear what the Steeda sounds like with its velocity stack design MAF housing, but I haven't had the chance.

So what this is all leading to is me thinking about how to make a "little" intake sound (you have to have a little---LOL) and get in more air without it sounding like a sick elephant stuck in the mud surrounded by crocs.

First I removed the silencer under the air box. Sounded gay. So I made a block off plate for the hole left behind because the silencer itself is gay. The tone increased, but not in a bad way. Linear and well integrated with the stock exhaust.

Then I tried the lid off the box (I have a K&N installed). Super gay. WOT was killer, but it sounded sad everywhere else. Not a good smooth tone.

So, I got to thinking about how this thing pulls air in factory form. It has two snorkels going to the box. Good. They run to the grill area at the front of the car. Good. Then there is a restrictive snorkle gathering air from the opposite side of the grille. Bad. And the opening of the grill is blocked by a piece of thin plastic that directs air away from the intake and instead to the very top of the radiator (actually mostly right over the top since the radiator gets 99.9% of its air from the bumper) with only about a 2x2" hole nowhere near the entrance of the snorkle. Very bad.

So... I got out my tools and first removed the snorkle behind the grille. This left a nice opening in the radiator support that the snorkles from the box plug into. I then removed the thin plastic shield that keeps most of the air being rammed into the grill from getting to the intake. This required some cutting, but you never notice it because it is all hidden.

So now my engine has an enclosed airbox, with two entrances for air (which are now short), and it pulls air from under the entire grill bar. All good (or at least much, much better than stock).

The sound is perfect. Smooth and linear and most people think it was meant to sound that way. The power seems improved seat of the pants (and I am very attuned to that I assure you). Nothing draumatic, but nicely noticable.

Now, before you talk about water, just remember that the stock airbox has previsions to eliminate that threat for anything other than driving through water up the the window seals. Plus, rain, etc. is minimal in that area unless you again are driving through said flood (in which case even a stock Focus could be screwed).

Before you mention heat, think about a short ram. The heat impact there is minimal (been proven) especially with a shield, and it is right by the engine and radiator. A CAI is down by the road with radiates all kinds of heat, and the filter is still open in the engine compartment (plus the extra tubing hurts power which is why a short ram usually beats a true CAI for power). I am getting air from in front of the car. Is there heat there? Yes. But where does a new Mustang draw air? Same place. You can't completely get away from heat. But, I beleive I have the best area possible to draw air from, and when moving it will only get better.

So, that is my littlle DIY mod for the month. Wish I had pics, but it is almost impossible to get good shots down in there. I tried.
 
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#77 ·
I just install the RX-4870

www.pumaspeed.co.uk/product-KN-X-Stream-Air-Filter-and-adaptor-Ring---Mk3-Focus-ST_15609.jsp

I used the end of the stock filter as the support ring. Also the curved part of the lid needs 1/4 to 1/2 inch trim so the end of the filter can extend trough the hole. I took the entire box out and tried to mach up the radius from the lower lid. I am going to make an aluminum one later. I may post picks later but the PUMA website looks the same. Look close and you can see the nice trim job they did. This may be option for some people.
 
#79 ·
Here is my variation on your latest revision....


My newmisioned box, which after RTV'ing the hose no longer needs the hose clamp/bracket and is removable as a unit!


my backup([hihi]) box with templates...


Templates transferred...


Finished product!
 
#81 ·
What is the advantage of drilling the holes in the side of the box? Is the intake still restricted, even with the newmission mod? I would think these custom holes would pull in warm/hot air when the car is stopped.
 
#84 ·
The holes are in the area behind the headlight, so not exactly in the engine compartment. I drilled holes instead of cutting out a rectangular section so that I could tape up one(or all) if it was too loud or if I felt it hurt anything. I also have the spare airbox, so I can compare the effects of the two setups by driving each over time.

I'm gonna dyno it with the OEM airbox, then swap in the modded one, then do my exhaust.
 
#93 ·
Let me just reiterate what I said back on post #82...



referring to the new holes. The air box isn't sealed anymore. Just a bunch of random air being sucked in to a bunch of random openings with opposing forces.
 
#99 · (Edited)
By drilling the holes in the airbox..you completely made the ram air hose useless[cheers]
Exactly....your hole drilling in the airbox reduces the efficiency of the cold air you gained from the front two inlets and the newmission ram air is what I was saying....now your basically sucking in engine bay air temps instead of near ambient..therefore reducing your maximum effectiveness....[clap][clap]
Let me just reiterate what I said back on post #82...



referring to the new holes. The air box isn't sealed anymore. Just a bunch of random air being sucked in to a bunch of random openings with opposing forces.

OK, so it's been 4 weeks since I drilled the extra holes. Removed the entire assembly tonight to swap the OEM back in for a trip to the stealership tomorrow. Took pics of how it came out:

Hmm, looks like some dirt/debris impacted on the Outerwears....


Wait a minute, it looks like it's really dirty right over that 3 in tube. But that can't be, I drilled all those extra holes in the box to negate any advantage of ducting air in from below the bumper...


There is a distinctly large circular pattern to this dirty spot on the pre-filter. Must be from all those little holes I drilled...


Sarcasm aside, it looks like I'm still getting plenty of air from the 3" ducting to the drivers bumper triangle.
 
#89 · (Edited)
The other 2 tubes that are attached to the airbox didn't seem to hurt the big tube from depositing large leaves and candy wrappers onto the filter before the new holes were bored. I haven't opened it up again since I modded the mod.

ie. the box was never sealed or relying only on the 3in tube for 100% airflow.

What are you doing for our hobby?
 
#91 ·
Exactly....your hole drilling in the airbox reduces the efficiency of the cold air you gained from the front two inlets and the newmission ram air is what I was saying....now your basically sucking in engine bay air temps instead of near ambient..therefore reducing your maximum effectiveness....[clap][clap]
 
#95 ·
Ok, at what speed would I need to be traveling for "Ram Air" to actually take place? I've heard in the Mk1's it's over 100mph. Anyone know about the Mk3's? If ram air potential is truly in the near 100 mph range, I've never had it even with the holes closed up. I honestly don't think I've gone over 80 in this car.

But it sounds cool, and not as obnoxious as when running w/o the airbox lid. I'm satisfied. Until any of us can show numbers, all the conjecture in the world won't change the fact that my intake sounds better then OEM

Why?

Because RACECAR
 
#96 ·
I don't know about the ram air speed. I just know that I would prefer to pull air from outside the engine bay if I still had the factory airbox installed. To me, that's it's main advantage over most of the aftermarket setups.

Hey, please don't think I'm trying to knock a hole in your theories or mods... I'm just over-analyzing the situation like usual! [screwy] [;)]
 
#97 ·
It's OK. The restriction here, from a strictly Bernoulli stand point, is the MAF and throttle plate. All I've really done is ensure that when the throttle plate is opened wide, the airbox isn't holding anything up. Soon, I'll do something similar with the exhaust. Then that big air pump and it's inherent design will be fully controlling, not an NVH/packaging compromise made by the designers and engineers.
 
#98 ·
I concurr with TiStick based on my own experience.
The first thing I did after putting in a K&N drop-in was to drill 5 half inch holes in the front of the airbox. This proved good to both my SOP dyno and the by the gas mileage goin up just over 1 mpg. If you are moving, there is fresh air coming in there. And I haven't even removed the cover plates yet as there is some flow in already.

I next removed the snorkel and opened more air up there and saw a much smaller improvement.

I'm pretty happy until I get a cat back exhaust.

I guess I could measure the temperature there but I don't feel there is a real need to as this is air entering the area from the front of the car and cooler air will always push back warmer air.
 
#101 ·
Yep, you've proven that you're definitely still getting air & dirt from the newmission mod.

I'm wondering why you quoted me before the picture though. The pictures don't address any of my quoted concerns; i.e. airbox vacuum, warm air intake through the holes. I stated that ram air through the newmission tube would not be a concern, and you've shown that.
 
#102 ·
i.e. airbox vacuum, warm air intake through the holes. I stated that ram air through the newmission tube would not be a concern, and you've shown that.
Airbox vacuum, airbox vacuum, airbox vacuum. Yes it's been shown that there's still suction through the NewMission tube. No dirt where all the holes are show there's no suction there. I'd bet if all those holes weren't there that one dirty area on the filter would be 5x dirtier due to more suction because of airbox vacuum.
 
#105 ·
Are we boring you? Sorry you don't find the discussion interesting.

I wonder if he would have stayed in the discussion if more of us had boosted his ego and told him that we thought drilling holes in his airbox was a great idea?
 
#107 ·
I have a question I had just taped the silencer and removed the entire snorkel, BUT personally I could not cut the flap underneath it so I just removed that entire piece....would that dwindle the funneling effect of having that there to guide it towards the opening of the intake?

btw swore more than a few times trying to take out that entire piece out from under where the snorkel would be.
 
#108 ·
Funny how this is becoming so popular since I posted it in back in May of 2012. The mod even has its own sticky now with better pics than my original ones.

It would be nice to see if this helps on the dyno. I am sure it would if some air could be directed towards the front of the car with a fan.
 
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