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The Darwinator.
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Discussion Starter · #1 ·
Are there any cold air intakes out there for the 330 that use the stock filter? I'm reluctant to switch to a cone or K&N style that filters less dirt.

B.
 

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King of Rear Clunks
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Strictly speaking, the stock intake IS a 'cold air intake' since it takes in air directly from outside the engine compartment.

You might wanna do a search for 31st330i's old posts on this.
 

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Lap Dog
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1,216 Posts
If you open the intake box and take a look at the stock paper filter, you will see why it is so restrictive. The thick layer of foam behind it does not help much either. If you change your oil regularly, you'll be OK. BMW engines are strong and will likely hold up better than most other parts even with a less restrictive air filter.
 

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brave1heart said:
If you change your oil regularly, you'll be OK. BMW engines are strong and will likely hold up better than most other parts even with a less restrictive air filter.
But dirty air is burnt in the combustion chamber and doesn't (shouldn't) go into the oil. Dirty air will affect your air mass sensor and possibly your catallytic converter. An incorrect amount of air (as measured by the sensor) will trigger an incorrect amount of fuel, which will affect performance. I think any potential gain offered by a free flow filter (K&N and others) are negated by the accompanying dirt. Fact is the advantages of K&N have been discussed long and hard in many forums and no one has yet produced conclusive data substantiating any measurable gain (OTOH, I've seen dyno charts that show a loss of power).
 

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The Darwinator.
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Discussion Starter · #6 ·
Sorry...didn't mean to reignite the whole K&N/CAI/what's best argument. I guess what I'm looking for is something more along the lines of a heat shield for the intake and MAF...sort of like a real basic CAI upgrade. I haven't seen anything of that nature. I figured a CAI that used the stock filter would be pretty much that, with maybe a slightly relocated/reshaped/more sealed intake; but haven't seen any.

B.
 

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Now with Nano
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brave1heart said:
If you open the intake box and take a look at the stock paper filter, you will see why it is so restrictive. The thick layer of foam behind it does not help much either. If you change your oil regularly, you'll be OK. BMW engines are strong and will likely hold up better than most other parts even with a less restrictive air filter.
wrong-o

the stock filter isn't very restrictive at all. the foam layer actually keeps the air filter (paper element) cleaner for a longer time by trapping larger particles.

you could always do what I did and use the E36 filter (search archives for my posts on this). it won't buy you much, though.

the significant restrictions in the intake tract isn't the filter (it almost never is on any modern car), it's the air box and sometimes the tract between the air box and throttle body. even on the original 1.6L miata, someone measured the pressure drops of the entire intake tract from throttle body to the inlet snorkle. an extremely dirty stock paper filter amounted to only something like 3% of the total restriction. hardly anything to worry about.

another thing to keep in mind is that all E46s use the same air filter, EVEN the M3. the M3 is definitly not choked off. in fact, I think there's only a very minor bump in HP when replacing the stock air box.
 

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JetBlack330i said:

But dirty air is burnt in the combustion chamber and doesn't (shouldn't) go into the oil. Dirty air will affect your air mass sensor and possibly your catallytic converter. An incorrect amount of air (as measured by the sensor) will trigger an incorrect amount of fuel, which will affect performance. I think any potential gain offered by a free flow filter (K&N and others) are negated by the accompanying dirt. Fact is the advantages of K&N have been discussed long and hard in many forums and no one has yet produced conclusive data substantiating any measurable gain (OTOH, I've seen dyno charts that show a loss of power).
before dirty air is burned, it is compressed and a slight amount blows by the rings. even though it is exploded, some stays in the engine.

in fact, if you search my posts, you will see that someone dynoed a one or two horsepower LOSS from going to a K&N over stock on a 1.9L Z3.

how can you have an incorrect amount of air? the ECU will compensate for it. were you speaking of the case where the MAS is contaminated (from something like over oiling one's K&N)?
 

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Lap Dog
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31st330i said:


the significant restrictions in the intake tract isn't the filter (it almost never is on any modern car), it's the air box and sometimes the tract between the air box and throttle body.
I am not an engineer and I am not qualified to argue the pros and cons of the stock paper filter but I can tell you that the improvement in acceleration due to the ECIS CAI that I installed is very noticeable. When am I supposed to experience a loss in power - immediately or after a few months? So dirt accounts for only 3% loss in the stock filter but it could be a lot more than that with a K&N filter?!? Tell me more.
 

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.
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brave1heart said:


I am not an engineer and I am not qualified to argue the pros and cons of the stock paper filter but I can tell you that the improvement in acceleration due to the ECIS CAI that I installed is very noticeable.
The improvement, or the perceived improvement? My car always feels faster after a wash and wax. It also feels noticeably faster when I drive at night.
 

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Now with Nano
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brave1heart said:
I am not an engineer and I am not qualified to argue the pros and cons of the stock paper filter but I can tell you that the improvement in acceleration due to the ECIS CAI that I installed is very noticeable.
that's because it replaces the whole air box, not just the filter.

brave1heart said:
When am I supposed to experience a loss in power - immediately or after a few months? So dirt accounts for only 3% loss in the stock filter but it could be a lot more than that with a K&N filter?!? Tell me more.
the documented power loss was from a drop in panel filter. heres' the page:
http://coolynx.virtualave.net/z3/upgrades/performance/kn-filter/kn-filter.htm

here's a post I made a while back
http://bimmer.roadfly.org/bmw/forums/e46/forum.php?postid=108421&page=1

no. what I said that was a dirty stock filter accounts for ~3% of the total restriction of the intake tract on a miata. actually, it was more like 7% but the point is still that the filter is not a significant restriction, the air box is. here's the article:
http://www.autospeed.com/A_0892/article.html
 

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Lap Dog
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31st330i said:


that's because it replaces the whole air box, not just the filter.
Thanks for the links - that was interesting. I'm wondering then why more tuners don't use the stock paper filter :dunno:
 

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Now with Nano
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because they'd need to develop a new air box and that would be mean significantly more R&D dollars and end user cost. frankly, I'd be first in line if someone came out with a reasonale priced replacement airbox. that's whay I started mucking around with my ESIS idea (search archives) a while back. perhaps a combination of my ESIS idea (which is still installed on my car) and what kevin has posted on fanatics regarding removing the MAS screens would be the way to go.
 

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31st330i said:

how can you have an incorrect amount of air? the ECU will compensate for it. were you speaking of the case where the MAS is contaminated (from something like over oiling one's K&N)?
I was thinking of both.
a) If dirt (including oil) contaminates or damages the sensor, the measurement wouldn't be accurate.
b) the sensor measures what is supposed to be clean air. If part of that measured air turns out to be something else (dirt, oil, etc) the stoichiometric ratio is affected and performance suffers.
 

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JetBlack330i said:

I was thinking of both.
a) If dirt (including oil) contaminates or damages the sensor, the measurement wouldn't be accurate.
b) the sensor measures what is supposed to be clean air. If part of that measured air turns out to be something else (dirt, oil, etc) the stoichiometric ratio is affected and performance suffers.
I've understood point "a" for years but do you have any data to support point "b"? it would have to be some pretty dirty air to affect the air fuel ratio. changes in altitude and temperature have a much more significant affect (and are compensated for by the ECU based on readings from the IAT sensor and the altitude sensor).
 

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The Darwinator.
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Discussion Starter · #16 ·
From everything I've read, seems like the main idea behind a CAI is to reduce incoming air temp. Air flow already seems to exceed the needs of the engine. (Thus the term COLD air intake? :eeps:) That's my goal here.

31st, I was reading up on your heat shielding tinkering...seems like that's the way to go. It'd be nice to shield the entire air intake system from engine heat...maybe fiberglass or carbon fiber...I'm by no means a materials engineer. The ultimate method may be to create a separate compartment in the engine bay insulated from engine heat...I doubt this is cost effective, and would probably need to engineered in and factory installed. Shy of that a bolt in heat shield would be a good step. (Of course, this is all my opinion and should not be taken by anyone as fact, only speculation.) I'm not sure how feasible that is.

I noticed there's a guy on here with the means to create chrome gauge rings...anyone with the capability to make something like the heat shield? Jim C, you may have some customers here in this thread.

Beyond that, I guess it's time to start tinkering with heat resistant tapes.

B.
 

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31st330i said:


I've understood point "a" for years but do you have any data to support point "b"? it would have to be some pretty dirty air to affect the air fuel ratio. changes in altitude and temperature have a much more significant affect (and are compensated for by the ECU based on readings from the IAT sensor and the altitude sensor).
Yeah, but is there a dirt sensor? How does the ECU compensate without one.
Theoretically, the ideal fuel ratio is specified in molecules: 14.7 molecules of oxigen for one of gasoline. If one of the supposedly oxigen molecules turns out to be dirt didn't that ratio just change?
You're right that it would take a lot of dirt to affect performance in practice. But it's also true that in practice any extra air afforded by free-flow type filters such as K&N is very small. I'm simply saying that any gains would be negated by the extra dirt that can pass through. If you're aggressive with the oiling (to trap more dirt), then the oil itself does the harm.
 

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Bob330Ci said:

Beyond that, I guess it's time to start tinkering with heat resistant tapes.
That's been done and discussed in e46fanatics. Search posts by a KevinJ_2K1_325ci.
He eventually gave up in favor of a firewall a-la ECIS CAI.
Recently he gave up that in favor of the factory box plus removing the MAF screen.
Before you jump on it, there seem to be some reports of engine lights comming on and tranny failure. :yikes:
 

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The Darwinator.
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Discussion Starter · #19 ·
tranny failure = bad.

B.
 
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