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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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  #1  
Old 08-17-2017, 07:38 AM
SPDSKTR SPDSKTR is offline
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A message for you noobs who want a cold air intake...

Yesterday, I decided to hook my OBD-II Bluetooth dongle up to my E46 and read a handful of parameters through the Torque app, one of which was intake air temperature (IAT). The ambient air temperature at that time was approximately 85F.

While sitting still at idle, the temperature read just shy of 100F... about 97F. I should note that my car was not entirely warmed up yet, but very close.

Once I got up to 60 MPH, the temperature was reading at...

Wait just a minute. Let me add a few other things here before I go telling you what it said.

1) Yes, my car is supercharged. That means it can pull more air in than a non-boosted E46.
2) Yes, my car is supercharged. That means more heat in the engine bay, which can heat up hoses, tubes, etc. much more quickly.
3) My car does not make boost until I really press the throttle down.
4) I am using the stock airbox.

Let me repeat that last one:

I have a supercharged ZHP and am using the stock airbox.

Now... onto the results...

At 60 MPH with steady throttle, the engine is pulling a vacuum and making zero boost, which means the engine is pulling however much air it needs to pull, just like a stock E46. With that said, my IATs read out at 89F. That was just 4F above ambient temperature!

On my first E46, I had an ECIS intake. With it, IATs at highway speeds were about the same. Except with the ECIS intake, I had to deal with an oiled filter, which always ran the risk of ruining the MAF because of just a little too much oil. Alternately, if I didn't oil the filter enough, it would allow for contaminants to enter the engine, causing even bigger problems than a bad MAF.

So what am I trying to say through all of this?

KEEP YOUR STOCK AIRBOX AND FILTER AND SAVE YOURSELF THE MONEY!

Last edited by SPDSKTR; 08-23-2017 at 08:24 AM. Reason: Clarification.
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  #2  
Old 08-19-2017, 03:59 PM
SamxK SamxK is offline
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Thanks for the research and info! I read it a few times and understand much better.
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Old 08-29-2017, 12:04 PM
SPDSKTR SPDSKTR is offline
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How about another testimony?

I went to a car show last weekend (not this past Saturday, the one before) and a guy had an E36 M3 there which had a metal-tube "cold air" intake (think of a typical "short-ram" intake you see for $20 on eBay). There was a mobile dyno at the car show and he wanted to do some pulls. I told him I would hook up my OBD-II dongle so we could read other parameters on his car to see what it was doing. One of these things was his IAT.

The ambient air temperature was upwards of 94F, his hood was open, and there were two decent fans channeling air through his engine bay. While sitting at idle, his IATs were around 142F! When he did his pulls on the dyno, they spiked up to 146F!

That metal pipe was soaking up a LOT of heat from his engine and noticed that where his air filter was sitting, he was sucking in nothing but hot air. Sure, he was probably pulling more air volume from the large filter, but it was nothing but hot (and most likely oily) air. After showing him my IATs at idle (which were far below 140F), he realized how good the stock airbox design really is and declared he was swapping back over to it the minute he got home.
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Old 11-18-2017, 05:48 AM
Ali-Montreal Ali-Montreal is offline
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so replacing your intake with any aftermarket is just for the sound and probably less performance ?
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Old 11-18-2017, 09:13 AM
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Originally Posted by Ali-Montreal View Post
so replacing your intake with any aftermarket is just for the sound and probably less performance ?
That`s correct....it`s been proven many times that there are virtually no performance or mileage gains to be had from aftermarket CAIs.
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Old 11-18-2017, 09:29 AM
Ali-Montreal Ali-Montreal is offline
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but the sound is sexy
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Old 11-18-2017, 01:03 PM
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but the sound is sexy
I guess beauty is "in the ear of the beholder"....many refer to it as "annoying"....
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  #8  
Old 11-20-2017, 10:54 AM
SPDSKTR SPDSKTR is offline
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Originally Posted by Fast Bob View Post
I guess beauty is "in the ear of the beholder"....many refer to it as "annoying"....
I like my intake noise.
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Old 11-24-2017, 12:50 AM
johnnyfaire johnnyfaire is online now
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Quote:
Originally Posted by SPDSKTR View Post
How about another testimony?

I went to a car show last weekend (not this past Saturday, the one before) and a guy had an E36 M3 there which had a metal-tube "cold air" intake (think of a typical "short-ram" intake you see for $20 on eBay). There was a mobile dyno at the car show and he wanted to do some pulls. I told him I would hook up my OBD-II dongle so we could read other parameters on his car to see what it was doing. One of these things was his IAT.

The ambient air temperature was upwards of 94F, his hood was open, and there were two decent fans channeling air through his engine bay. While sitting at idle, his IATs were around 142F! When he did his pulls on the dyno, they spiked up to 146F!

That metal pipe was soaking up a LOT of heat from his engine and noticed that where his air filter was sitting, he was sucking in nothing but hot air. Sure, he was probably pulling more air volume from the large filter, but it was nothing but hot (and most likely oily) air. After showing him my IATs at idle (which were far below 140F), he realized how good the stock airbox design really is and declared he was swapping back over to it the minute he got home.
Now, aluminum heats quickly and cools quickly. So, imagine airflow over this aluminum Tubing. It's temp will go down.

Plastic takes longer to heat, so better air temp at idle. Generally, more stable.

Cold air intakes, when driving, get colder air into the MAF, but if made from aluminum Tubing are not good for normal driving conditions, like long idle, and instead are better for racing.


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Last edited by johnnyfaire; 11-24-2017 at 01:04 AM.
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Old 11-24-2017, 01:02 AM
johnnyfaire johnnyfaire is online now
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Quote:
Originally Posted by SPDSKTR View Post
Yesterday, I decided to hook my OBD-II Bluetooth dongle up to my E46 and read a handful of parameters through the Torque app, one of which was intake air temperature (IAT). The ambient air temperature at that time was approximately 85F.

While sitting still at idle, the temperature read just shy of 100F... about 97F. I should note that my car was not entirely warmed up yet, but very close.

Once I got up to 60 MPH, the temperature was reading at...

Wait just a minute. Let me add a few other things here before I go telling you what it said.

1) Yes, my car is supercharged. That means it can pull more air in than a non-boosted E46.
2) Yes, my car is supercharged. That means more heat in the engine bay, which can heat up hoses, tubes, etc. much more quickly.
3) My car does not make boost until I really press the throttle down.
4) I am using the stock airbox.

Let me repeat that last one:

I have a supercharged ZHP and am using the stock airbox.

Now... onto the results...

At 60 MPH with steady throttle, the engine is pulling a vacuum and making zero boost, which means the engine is pulling however much air it needs to pull, just like a stock E46. With that said, my IATs read out at 89F. That was just 4F above ambient temperature!

On my first E46, I had an ECIS intake. With it, IATs at highway speeds were about the same. Except with the ECIS intake, I had to deal with an oiled filter, which always ran the risk of ruining the MAF because of just a little too much oil. Alternately, if I didn't oil the filter enough, it would allow for contaminants to enter the engine, causing even bigger problems than a bad MAF.

So what am I trying to say through all of this?

KEEP YOUR STOCK AIRBOX AND FILTER AND SAVE YOURSELF THE MONEY!
You just said that because air filters that use oil can, and do, harm your MAFs, don't use CAIs.!?!

How about just not using air filters that require oil.

Colder air is good when it's hot out.

Also, I have a stock air box and I get constantly 20% higher numbers on my sensor than the actual air temp outside. When I'm cruising at 60mph, and with light engine load, it doesn't drop much. maybe it'll drop 5% more. But it has never even gotten within 5% of actual ambient temp.

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Old 11-24-2017, 11:31 AM
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Quote:
Originally Posted by johnnyfaire View Post
You just said that because air filters that use oil can, and do, harm your MAFs, don't use CAIs.!?!

How about just not using air filters that require oil.

Colder air is good when it's hot out.

Also, I have a stock air box and I get constantly 20% higher numbers on my sensor than the actual air temp outside. When I'm cruising at 60mph, and with light engine load, it doesn't drop much. maybe it'll drop 5% more. But it has never even gotten within 5% of actual ambient temp.

Sent from my ONEPLUS A3010 using Bimmerfest mobile app
To which, the answer is SO WHAT ? Do you have any idea of how many BTUs are generated by an aluminum engine in a (basically) sealed environment ? It`s enough to heat a 2-car garage in the middle of winter, so don`t expect any CAI to equal ambient temps, it ain`t gonna happen.
You want a higher level of efficiency ? Wrap the airbox in DynaMat or a similar product that the high-end stereo installers use....
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Old 11-24-2017, 12:05 PM
johnnyfaire johnnyfaire is online now
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Quote:
Originally Posted by Fast Bob View Post
To which, the answer is SO WHAT ? Do you have any idea of how many BTUs are generated by an aluminum engine in a (basically) sealed environment ? It`s enough to heat a 2-car garage in the middle of winter, so don`t expect any CAI to equal ambient temps, it ain`t gonna happen.
You want a higher level of efficiency ? Wrap the airbox in DynaMat or a similar product that the high-end stereo installers use....
I was thinking of painting mine white to reflect the heat, lol, and what my IAT readings. Really, anything to help move heat away from the stock air box is helpful, especially if the IAT is inside the MAF.

I was trying to clarify your post. And, yes, anything outside of constant air movement, as with racing, cold air intakes don't help the daily driver much at all. It robs performance at idle and stop and go.

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Old 11-24-2017, 02:11 PM
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Quote:
Originally Posted by johnnyfaire View Post
anything outside of constant air movement, as with racing, cold air intakes don't help the daily driver much at all. It robs performance at idle and stop and go.
L]
Actually, a CAI does help all the time, most cars without one just suck that hot underhood air into the intake....

And, painting the airbox wouldn`t do diddlysquat, the paint has zero insulating value. I suggested DynaMat because it is both reflective and insulating.
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  #14  
Old 11-27-2017, 01:42 PM
SPDSKTR SPDSKTR is offline
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Quote:
Originally Posted by johnnyfaire View Post
You just said that because air filters that use oil can, and do, harm your MAFs, don't use CAIs.!?!

How about just not using air filters that require oil.
That's one reason. If you use a dry-flow foam filter that "increases airflow by 30%" or whatever, you're also allowing 30% more contaminants to enter your engine.

Quote:
Originally Posted by johnnyfaire View Post
I was thinking of painting mine white to reflect the heat, lol, and what my IAT readings. Really, anything to help move heat away from the stock air box is helpful, especially if the IAT is inside the MAF.

I was trying to clarify your post. And, yes, anything outside of constant air movement, as with racing, cold air intakes don't help the daily driver much at all. It robs performance at idle and stop and go.
Colors only matter when it comes to heat caused by light. Think about wearing a white shirt vs. a black shirt in the summer sun. You notice that difference, don't you? You won't notice a difference when it's night, though.

In order to better insulate your airbox, do like FastBob said and use actual insulating material (such as DynaMat) on your stock airbox and use the stock paper filter. You can also try the kidney grille scoops to try to channel more air directly into your airbox, but whether or not they actually work is beyond me.
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Old 11-27-2017, 05:11 PM
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Originally Posted by SPDSKTR View Post
That's one reason. If you use a dry-flow foam filter that "increases airflow by 30%" or whatever, you're also allowing 30% more contaminants to enter your engine.



Colors only matter when it comes to heat caused by light. Think about wearing a white shirt vs. a black shirt in the summer sun. You notice that difference, don't you? You won't notice a difference when it's night, though.

In order to better insulate your airbox, do like FastBob said and use actual insulating material (such as DynaMat) on your stock airbox and use the stock paper filter. You can also try the kidney grille scoops to try to channel more air directly into your airbox, but whether or not they actually work is beyond me.
The leading edge of the hood, where the stock intake pickup is located, is a high-pressure area....you can`t do much better than that. The engineers spent a lot of R&D money on getting the most effective intake system possible. Proof of this is the fact that the stock intake can take The Pepsi Challenge against any aftermarket CAI out there, and come out at the top of the heap....
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Old 11-27-2017, 05:37 PM
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If I was that concerned about lowering the intake air for some mythical 1/2 hp gain I would use a low pressure water pump, bit of hose and some pipe insulation. Wrap the hose around the a/c line and then run it to the air intake snorkel. Put the pump in the hose where convenient and insulate it all. Run the a/c and pump when you feel the need for speed coming on. Turn the a/c off and feel that awesome 1/2 hp boost.

For the truly lazy and cheap a bag of ice works just was well.

Before anyone thinks this is just made up. I have seen both done in real life.

The only cars that got anything useful from this were a few turbo cars and 2 supercharged cars. One of the supercharged cars was mine.

The ice bath lowered spark knock noticeably. Was not worth the effort to be honest. Heck the supercharger was not worth the effort looking back on it all. $5000 with $8000 when it was all said and done.

I guess its nice to be able to say "been there done that" but when I look across all the headaches I dealt with vs how easy to just drive the car before all of that mess was I realize just how much wasted money it was.

This was on a corvette btw. My current corvette has a 383 stroker in it and would eat the supercharged corvette I used to own for lunch. No replacement for displacement
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