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2004 325CI manual (Japan Rot)
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Discussion Starter · #1 ·
Ive seen so many conflicting reports on cold air intakes for our E46's. Some claim to not even produce sound (Youtube video I saw) nor power, and in some cases like ebay intakes REDUCE power because IAT's skyrocketing.

But what about quality intakes? For my car personally I also have a set of catless headers installed, would this affect the performance of the intake? Im aware that intake and exhaust go together like syrup and pancakes, But it seems our cars could be the exception? Id really like to do some runs on the dyno with an without as I plan on doing a tune sometime this year I hope :)

With those 2 other modifications In mind, is this a waste of money? Ive seen things that have polar opposite experiences but nothing conclusive with hard facts.
 

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'02 330i 5-Speed
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Many many threads on here about CAIs.

Technically our cars come from the factory with cold air intakes since the air enters the airbox from the outside, not the engine bay. So what folks are really asking about is cone filters.

BMW did offer a performance intake, so there are some gains to be had, but very marginal. And there is data to show that an aftermarket intake can benefit power, but only if the intake tubing is the proper length, i.e. the filter's down under the fender. And you're still only talking about a handful of hp at the most.
 

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Look at where the intake gets it’s airflow, those cone intakes recirculate hot air unless they have a long tube. Of course, those tubes expose the cone to the elements and water will reek havoc with the paper cone. The BMW intake gets it’s air from the front of the car at the kidney grills.
 

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How insightful. thanks for the contribution. 🙄
I'm so sarcastic myself, I pick up on it. OP, All2Kool was being honest and succinct. Most of the parts on our cars are there for a reason. BMW engineers didn't forget that the engine needs air, fuel, and spark and gave you an intake that works just fine the life of the car. Don't do a cone filter

...and, from what I've read here for the last 15 years, the only thing a decent 'other' air filter will do is give you a different sound, or maybe, combined with $$$ of other things will give you some extra HPs...but as mentioned above, the intake might only account for a few HPs, if even. Ours breathes just fine.
 

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The car already has a cold air intake, look at where the air comes from!
Most aftermarket intakes utilize a larger filter bereft of a sealed enclosure. So what do they do, give you a fence with foam around the top. Do you think that's a better seal against hot air under the hood than a sealed box?

A true box that ONLY draws air from outside and a larger filter is good.
Unfortunately I am only aware of one, The factory performance air intake box.

Sound does not = HP.
 

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long tube intake, i've ran one for years never hydrolocked anything. water 100% gets into your stock filter system, some peoples kids..
 

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Yes, but the design of the airflow is that the air comes in near the bottom of the airbox, so any drawn in water that hasn't evaporated on its way in will collect and run down to the bottom of the airbox, where it will mix/vaporize with incoming air. So at worst, with a stock intake, you are drawing in air that contains evaporated water.
 

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I see you have a 325ci , bmw performance intakes are still available for your car , I guess at around $400 ,or you can grab one used .It's the only option I would consider .Proven gains , one atitional air inlet ,quality paper filter , not the oiled reusable ones that will destroy your maf
 

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I see you have a 325ci , bmw performance intakes are still available for your car , I guess at around $400 ,or you can grab one used .It's the only option I would consider .Proven gains , one atitional air inlet ,quality paper filter , not the oiled reusable ones that will destroy your maf
oh the painful fact checking, oiled filters don't ruin mafs. Dinan made a long tube option that doesn't void your factory warranty, they sound better and perform better. carry on
 

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Ive seen so many conflicting reports on cold air intakes for our E46's. Some claim to not even produce sound (Youtube video I saw) nor power, and in some cases like ebay intakes REDUCE power because IAT's skyrocketing.

But what about quality intakes? For my car personally I also have a set of catless headers installed, would this affect the performance of the intake? Im aware that intake and exhaust go together like syrup and pancakes, But it seems our cars could be the exception? Id really like to do some runs on the dyno with an without as I plan on doing a tune sometime this year I hope :)

With those 2 other modifications In mind, is this a waste of money? Ive seen things that have polar opposite experiences but nothing conclusive with hard facts.
The cold hard facts on CAIs are this. (pardon the pun:))
It's all about combustion. And you don't have combustion without fuel and oxygen.
The computer can easily send more fuel into the engine, but it has little option for air. (I know, we could talk about scavenging, porting, etc. but just to keep it simplified)
Logically, the more oxygen molecules you can stuff into the combustion chamber, the better.
A naturally aspirated engine can only be fed a fairly fixed amount of air for each intake stroke.
When I say fairly, it means that depending on the density/temperature of the intake air, and altitude, this will change slightly.
Everyone talks about density. What does it mean?
It means that more dense air has more oxygen molecules in it. Temperature and density are related in this case.
So, naturally, colder air has a higher combustive output, because there are more oxygen molecules in the air charge.
Now you can imagine what happens when you bring a turbo or a supercharger into play.
You are now compressing a whole bunch more oxygen molecules in the same space.
Add an intercooler and you're helping to maintain that "volumetric efficiency".
Hope that makes sense.

At the end of the day though, is the 3hp you might gain, worth the cost and aggravation of a CAI?
I agree with everyone here who talks about K&N cone filters. they typically install under the hood, so cold air is basically non-existent.
They are another item to maintain and the required oil "will" insulate your MAF and you will start having drivability issues.
 

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oh the painful fact checking, oiled filters don't ruin mafs. Dinan made a long tube option that doesn't void your factory warranty, they sound better and perform better. carry on
I won't take your word for it
 

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I won't take your word for it
You don't have to, oiled filters have been around for years. Do you think it's a conspiracy to destroy mafs with an oiled filter and you are here to educate the world? The simple facts are, oiled filters don't ruin mafs. People ruin mafs, how? They apply way too much oil to the filter. You can do the research and educate yourself on the gains that are "proven" by members of this community. You can search for Dinan long tube intakes and see that they do offer them, all the while not voiding your factory warranty.
 

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You don't have to, oiled filters have been around for years. Do you think it's a conspiracy to destroy mafs with an oiled filter and you are here to educate the world? The simple facts are, oiled filters don't ruin mafs. People ruin mafs, how? They apply way too much oil to the filter. You can do the research and educate yourself on the gains that are "proven" by members of this community. You can search for Dinan long tube intakes and see that they do offer them, and don't void your factory warranty.
Ahh so you admit oil destroys mafs. Simple facts maybe for you that you are simplistic. I think you gave yourself the role of educator of the world, not me. I am happy to hear at least that you admit oil incorrectly used on the filters ruins mafs. That would be a proper response to my post. So instead of using a perfectly fine paper cheap filter, let's introduce another failure point in our cars.
 

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Ahh so you admit oil destroys mafs. Simple facts maybe for you that you are simplistic. I think you gave yourself the role of educator of the world, not me. I am happy to hear at least that you admit oil incorrectly used on the filters ruins mafs. That would be a proper response to my post. So instead of using a perfectly fine paper cheap filter, let's introduce another failure point in our cars.
rofl, good day!
 

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For me the E46 looks like it wouldn't respond well to any bolt on performance mods. One of the things that struck potential buys off my list were those horrible looking pod filters and any sort of "performance" parts. Mind you, I'm chasing a clean example not a race car. It's already designed for performance

If I was to answer the OP's original question, I'd say yes the aftermarket cold air intake is a waste of money as it already has one. For the same money you could put a refresh kit through your Vanos, get your injectors serviced and fix some vacuum leaks, along with a new set of (paper) filters and fluids.

THEN you would notice some extra horsepower as well as know you've got as much as you can out of it stock, and it won't sound stupid as well.
 

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Hi, I have a Dinan long tube intake. I've never had any issues but now I have a true Dinan filter & water sock; before it was a k&n and a rag of a sock.

When I ran bimmerbrakes headers w/o cats it ran fantastic(no dyno numbers though). I'm considering doing that again if I can find some good cheap headers.
 

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Discussion Starter · #19 ·
Hi, I have a Dinan long tube intake. I've never had any issues but now I have a true Dinan filter & water sock; before it was a k&n and a rag of a sock.

When I ran bimmerbrakes headers w/o cats it ran fantastic(no dyno numbers though). I'm considering doing that again if I can find some good cheap headers.

Do they still make the dinan longtube intake?
 

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I don't think so but if you look you should be able to find one. I'll be running mine with an actual Dinan filter after new plugs and coil packs if I can get info on them.
 
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