mfeldhs

When I was installing my SRI I noticed that there was a secondary filter permanently attached to the air box lid. Does anyone know what that is? Can you run it without it? I was thinking about taking it out of my wife’s 09 xB. Also what is the extra air box mounted to the intake tube closer to the motor?

Bdog4life

The secondary filter is the charcoal filter that is what makes your intake emissions legal. You can run without it but technically you wont pass a SMOG test if you do. The second "air box" is a silencer for your intake.

MiniFridge

Anyone have pics of all of this? Has anyone taken these additional restrictions off and seen what performance gains thee are to be had for "free"?

TrevorS

iTrader: (1)

Speaking for my butt dyno, removal of the intake emissions filter from the OE air-box cover has no perceptible impact on performance. The mod to the OE that really packs a punch is removal of the snorkel. Beyond that, you can convert the OE into CAI, or you can buy an aftermarket CAI or SRI.

MiniFridge

Alright, as soon as the wife leaves to go shopping I'll go pop the hood and try and put eyes on the snorkel. She is never happy when I start removing parts on a new car. Any hacking or cutting required or just simple nuts, bolts and clips?

CIONIDE

iTrader: (1)

Not sure, but I think this DIY is what you're looking to do, it's to convert the OEM intake into a CAI:

https://www.scionlife.com/forums/sho...d.php?t=111524

TrevorS

iTrader: (1)

The snorkel is easiest to remove with the battery out. There's a bolt ahead of the fuse box into the fender, two snaps anchoring the intake flare and the loop, and finally disconnecting and extracting the loop. It's completely reversible and definitely no cutting or such required. The parts just couple together.

ScionFred

iTrader: (1)

Just to clarify, that filter is only to prevent venting fuel vapors to atmosphere through the airbox. Unless an unusually well-trained and gung-ho emmissions tester actually opens the air box to look for it and notices it missing, you'll fly through any emmissions test. Here in MD all they do is plug into the OBD2 port and look for codes.

MiniFridge

Thanks for the feedback. I went and looked at it earlier and was very surprised that anyone would intentionally put crap like that on an intake. It's coming OFF.

Anyone noted any mpg improvements?

ScionFred

iTrader: (1)

You're welcome. FWIW, as previously stated, I agree that the charcoal filter isn't terribly restrictive. I just wanted to clarify that removing it should have no effect on passing an emission test in most, if not all, states. I'd be shocked if removing it resulted in a measureable mpg improvement and equally shocked if someone didn't claim that it did.

MiniFridge

Lol, I agree with your last statement for sure. I am more interested in popping the snorkle off because that cannot do anything positive for performance.

TrevorS

iTrader: (1)

Removal of the snorkel improves the ability of the engine to breath, forget mpg, the days of primitive engine designs are long gone. If your goal is mpg, leave the snorkel in and make a point of maintaining tire pressure. If your goal is overall responsiveness, dump the snorkel, go easy on the throttle, and maintain a respectable tire pressure (both the latter assist mpg). I use 35psi (when I don't forget ), but the recommended values are specified on a plate at the lower rear of the drivers door.

ScionFred

iTrader: (1)

It's funny how many little mods result in +3 mpg according to the modder yet the oems can't do the same thing with millions spent on R&D.

Actually the snorkel does draw air from a cooler location than the airbox will without it. IMO you'd gain more power by re-locating the snorkel similarly to the DIY link that CIONIDE posted. I'd get the TRD vent and place the snorkel end behind it. The downsides are that it won't sound any better and the snorkel may possibly be a bit small for maximum airflow at high rpm. Even better you could replace the snorkel hose with larger hose like Trevor did. This way you get improved sound, more flow and more peak power. Better still, adding a large scoop or velocity stack to the hose end would create a ram air effect at speed.

Hydro-lock shouldn't be a concern with this setup since the water would have to fill the airbox faster than it drains out before hydro-lock could occur. To be even safer, enlarge the existing airbox drain holes, add more or leave a small opening in bottom of the intake hose so there won't be enough vacuum to suck up water. Good luck.

TrevorS

iTrader: (1)

Just one question, perhaps I've totally overlooked something, but I'm unaware of any "drain" holes in the OE air-box. Please clarify !

Vlad1024

If I remember correctly there are a few small holes in the bottom of the air box.

TrevorS

iTrader: (1)

The only holes I'm aware of in the bottom of the OE air box are those used to install the three mounting bolts. They don't provide either air or water passage.

Vlad1024

Its a little fuzzy but i remember a car having them but I don't remember which...

TrevorS

iTrader: (1)

It so happens, I was particular about this. I very deliberately installed a CAI utilizing the OE air-box. However, to do so safely, I needed a way to allow air bypass in case of intake block due to water presence. My solution was to make an opening in the bottom of the OE airbox and install a flap over it so that normal air intake would be from the left front fender, not the engine compartment. Here is a photo of my solution.



You'll notice directly beneath my installed flap two bolts that anchor the air-box base to the transaxle (the third bolt not being visible in this photo, but no less present). The OE air-box base provides no openings were I show a flap -- I specifically created a hidden opening for the purpose of hydrolock protection. Speaking for myself, I never identified any openings within the OE airbox that would protect in any way against hydrolock. However, given the high location of the OE snorkel air inlet in the forward engine compartment, there was no need on Toyota's part to provide such protection. It's only if one chooses to modify the OE air inlet that such considerations become appropriate.

MiniFridge

Thanks all for the detailed replies. I'll check out Trevor's DIY and use that as a guide.

ScionFred

iTrader: (1)

My airbox came with these 2 drain holes in the bottom. I can't recall ever seeing a oem airbox that didn't have drain holes.