[SPDSKTR]

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 85ºF.

While sitting still at idle, the temperature read just shy of 100ºF... about 97ºF. 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 89ºF. That was just 4ºF 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!

 

[SamxK]

Thanks for the research and info! I read it a few times and understand much better.

 

[SPDSKTR]

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

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 140ºF), he realized how good the stock airbox design really is and declared he was swapping back over to it the minute he got home.

 

[Ali-Montreal]

so replacing your intake with any aftermarket is just for the sound and probably less performance ?

 

[Fast Bob]

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.

 

[Ali-Montreal]

but the sound is sexy

 

[Fast Bob]

but the sound is sexy

I guess beauty is "in the ear of the beholder"....many refer to it as "annoying"....

 

[SPDSKTR]

I guess beauty is "in the ear of the beholder"....many refer to it as "annoying"....

I like my intake noise. :eeps:

 

[johnnyfaire]

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

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 140ºF), 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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[johnnyfaire]

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 85ºF.

While sitting still at idle, the temperature read just shy of 100ºF... about 97ºF. 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 89ºF. That was just 4ºF 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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[Fast Bob]

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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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....

 

[johnnyfaire]

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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[Fast Bob]

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.

 

[SPDSKTR]

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.

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.

 

[Fast Bob]

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....

 

[crowz]

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

 

[SPDSKTR]

Someone messaged me on another forum and said they saw this post. They criticized this thread and ultimately asked me, "Why do the dyno graphs show horsepower gains, though?"

Let's take a look at a typical dyno run.

Notice anything that really stands out? I do. The hood is up with two industrial fans blowing air on the engine bay.

"But you have to so the engine stays cool!"

That's funny. The last time I checked, my hood is always DOWN when I'm going down the road.

"Duh. It has to be. What's your point?"

Most of these aftermarket intake systems are open-element filters. They just hang out in the engine bay, sucking in whatever air is available to them. So if you have the hood up with big fans blowing fresh, cold air over the engine bay, guess what that intake will do. Yup. That intake is going to be sucking in that fresh, cold air. Once you close that hood, you close off that supply of fresh air. The heat will immediately begin to build back up and that open-element intake is now sucking in (you guessed it) hot air.

You know... now that I'm thinking back on things, there seems to be one exception to this "all aftermarket intakes suck" mindset. I had an ECIS intake on my first E46 and, no joke, seemed to do a pretty good job of keeping things cool. I assume it's partly because it used the factory intake duct (located behind the kidney grilles) to help channel outside air into the intake bay and partly because it was completely sealed away from the rest of the engine bay. At idle, it was sucking some pretty hot air, but once I gave it a little gas and got moving, the temperatures dropped significantly. For specifics, here's a post I made over at E46Fanatics a few years ago:

I have an ECIS intake system with a universal K&N oiled filter (long, narrow filter). I upgraded the foam around the top of the heat shield with some thicker stuff to better seal off the box. In 95ºF ambient temperature in downtown Birmingham (major heat index with the newer asphalt, reflective buildings, etc.), I was reading a whopping 140ºF while sitting at a red light, surrounded by cars. At roughly 55% throttle (approximation), it dropped to 110ºF. Soon enough, it dropped down to 97ºF. :yikes:

Granted, I was also missing a piece of plastic under the intake bay, allowing the underside to be exposed to more open air.

Well... after that car suffered a tragic fate, I gave the intake to our very own smolck. Even he said it made more power after replacing the K&N cone filter I had on there with a Spectre open-ended filter. The following quote was taken from the ZHP Mafia forum:

I had the ECIS, hands down made the most power.

He also acknowledged it resulted in colder IATs than with his stock ZHP intake (when he had said ZHP):

SPDSKTR has a bluetooth OBD reader and with his ECIS intake he saw significantly lower intake temps than I did on my stock unit.

With all that said, maybe there is something to be said for the ECIS unit.

 

[mr_y82]

Good thread... I have a foam Pipercross filter, for the stock airbox, but it is still sitting in the box. I had some reservations about it, but my BMW tech doesn't think I should worry about increased contamination... I like the idea of a washable filter, but want to keep my engine happy as well...

 

[Fast Bob]

Good thread... I have a foam Pipercross filter, for the stock airbox, but it is still sitting in the box. I had some reservations about it, but my BMW tech doesn't think I should worry about increased contamination... I like the idea of a washable filter, but want to keep my engine happy as well...

Seriously, changing from anything other than a standard Mann-type filter will NOT do anything positive for your performance or mileage. They`re CHEAP....just replace it once a year, and all will be fine....

 

[johnnyfaire]

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.

Dynamat, good idea! Thanks

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