# "Open" vs "Closed" Cone Filters?



## XtremeRevolution (Jan 19, 2012)

No difference. 

I wouldn't grab an Ebay intake filter, however. Since you have the Injen CAI, replace the Amsoil EA filter with another Amsoil EA filter. The nanofiber filters have FAR better filtration than ebay generics. Refer to the link below:

Amsoil EA Filter

I believe the direct replacement is EaAU3050.


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## sx sonic (Nov 25, 2013)

Open is "better", but in most cases the differences are academic.

The reason being is that beyond a certain point more CFM flow potential will not net any gains. The majority of aftermarket cone filters already have an excess of flow potential for even a modified engine, a little more flow Potential over that by switching to an identical but "open" filter will be inconsequential.


A general guide is that "1 square of a K&N filter [folded pleate as opposed to a flat filter surface] will supply the air requirements for 4 to 4.5 hp [without causing a loss of flow]". Quote from David Vizard, renowned engine builder.
The same guide could be applied to any filter although if they flow less it'd be like 1"sq for 3-3.5hp.

So a filter good for 200hp would have a surface area of 50"sq (using the K&N filter guideline), that's enough unrestricted flow to support all the current mods for a 1.4t sonic. Anything above that won't offer any gains, with the exception of allowing full power longer as the filter becomes clogged.

To put that in perspective I just ran out and measure the K&N filter that came with my ZZP intake (for a Sonic 1.4t) and it has a surface area of ~75"sq, good up to around 300hp

I then guesstimated the the size the "open" part would be since mines a "closed" style.
I figured since the filter had a 5in dia the filter part would be 4in dia. That would add another 12"sq of filter area which would be good up to ~350hp


As you can see either style has more than enough area to support unrestricted airflow way beyond the limits of this engine. I imagine most of the aftermarket intakes for the Cruze come with a filter that isn't sized a whole lot different than mine either, so they should provide adequate airflow as well with a closed end filter.

If you want to go for an open end filter (idk what to call em either lol) go for it, there's nothing wrong with them, just in our application they are overkill. Just head ExtremeRevolutions advice and stay away from a generic EBay brand.


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## Merc6 (Jun 8, 2013)

My experience with ebay brand, they collapse easily when used and when you clean them. The metal screen they use to shape the pleats is super fragile. My best cheap filter was from PCP and it was strong enough I could sit on it. The filter was massive and won't fit in the bay or fender of a cruze or sonic. No clue on the level of filtration and I barely oiled it from previous maf situations on previous cars.


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## daktah (Mar 17, 2013)

Thanks for the advice guys.
The reason i saw these was i wanted to put a cai on my wifes 05 altima for christmas (without spending $200 like mine) to make it sound better and i saw these filters.
Speaking of which, do you think ebay intake tubing would be ok to go with and then just not cheap out on the filter? would a open filter make a difference with her 2.5l ~175hp since it has more displacement?


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## revjpeterson (Oct 2, 2013)

That's what I do on my Jeep. I got a $50 intake pipe from eBay and put a name-brand filter on the end of it.

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## Merc6 (Jun 8, 2013)

All depends on how you mount it and as long as this isn't one of those cars where an intake tube size changes the fuel trim. 


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## prince_bigd (Jul 16, 2013)

If you go with a cheap intake tube pick up one of the maf tuning kits that has the different size inserts that sit inside the tube around the maf. Spectre makes one fairly cheap, and I know many modern cars are very very picky about intake tube diameter around the maf. Basically the maf calculates airflow based on a formula using a specified diameter stock tube. When you alter tube diameter it still uses calculations for the old tube size. This means your a/f ratio will be off, could run lean/rich, even throw CEL lights. So while you can save money pay attention to keeping your maf as close to the stock location and tube diameter as possible and if needed look into one of those maf adapters


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## XtremeRevolution (Jan 19, 2012)

daktah said:


> Thanks for the advice guys.
> The reason i saw these was i wanted to put a cai on my wifes 05 altima for christmas (without spending $200 like mine) to make it sound better and i saw these filters.
> Speaking of which, do you think ebay intake tubing would be ok to go with and then just not cheap out on the filter? would a open filter make a difference with her 2.5l ~175hp since it has more displacement?


As the guy above me said so well, you need to keep the intake diameter the same if a MAF sensor is installed. 

If you can ensure that, or if the intake tube you replace doesn't have a MAF sensor on it, then yes you can use any tube and use a high quality filter. 

Sent from mobile.


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## daktah (Mar 17, 2013)

many thanks for the information.
ill have to take a look at her car after work.


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## revjpeterson (Oct 2, 2013)

I hadn't considered the MAF sensor, since my Jeep doesn't have one. In fact, it has nothing electrical connected to the intake at all (just 2 vacuum lines), which made for a very easy intake installation. 

This is the filter I used, which is sort of a hybrid between the "open" and "closed" designs you mentioned--with the end of the filter "closed," but made of filter material instead of being solid. I'm not sure how much difference it actually makes in the real world, and I'm sure that the "closed" filter has plenty of surface area for the horsepower needs. However, I like the concept of the air having a straight inlet parallel to the pipe instead of only bending in from a perpendicular angle, and at the time I could get it for a better price than the comparable closed-end filter. 

K&N RX-3990-1 Universal X-Stream Clamp-on : Amazon.com : Automotive

I don't imagine I'll do too much work on my Cruze Diesel like I did on my Grand Prix. I'll probably save all the mod budget for my Jeep, but 100,000 miles down the road, I won't rule out that I might get bit with the bug to start playing with the Cruze too.


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## XtremeRevolution (Jan 19, 2012)

I can't stress enough how important a good filter is for our cars, particularly the 1.4 Turbo. Turbos spin up to 200,000RM and those dust particles will sand off the vanes of the turbo over time. Do not run a cheap no-name filter. Always remember that a filter that flows more air will filter less, oiled or not. There is no exception. Some filters last longer and maintain flow when dirty, but that's a different story. 

I recommended the Amsoil EA because it is a universal pod filter that comes in many sizes and it does filter very well. 

Sent from mobile.


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## Merc6 (Jun 8, 2013)

Just Google'd the Maf housings and it's similar to the ones used on the 90's to 05 3100, 3400, 3500 3800 series engines where the sensor is in it's own detachable from the airbox housing with honeycomb still in tact. You just need a 4 bolt flange to connect the end that attached to the airbox so you can slip a coupler or filter over it. Leave that honeycomb in tact(do not gut it), it helps out a lot. Also can't tell but see if the airbox had other sensors like intake air temp. ZZP made an extension harness for the GM V6 to relocate it from in front of the TB to the fender where the cai filter is.


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