Air Filter and Intake Systems: What's the truth?

FIRST NOTE: I WILL TOLERATE ABSOLUTELY NO ARGUING ON THIS SUBJECT. ANY NASTY OR INAPPROPRIATE POSTS WILL CAUSE A REQUEST FOR IMMEDIATE DELETION TO A MODERATOR AND/OR ADMINISTRATOR, AND NO CHALLENGING THIS STATEMENT. I am open to reasonable discussion, and will edit this post to correct incorrect information as needed.

Read this, take home what you want to, this is NOT a final say on the subject, but do NOT comment unless you have read the whole thing through carefully.

This also addresses mainly mostly stock engines, and primarily is written with 2nd generation Dodge Ram trucks in mind, particularly gasoline engines.

Since this subject comes up all the time, I thought it would be good to have something everyone can reference to.

Are Cold Air Intakes (CAIs), Ram Air intakes, or aftermarket performance filters any good?

There is no standard answer on this subject. There's a lot of variables to be considered.

The first thing I want to address, is every one of us has to understand almost all aftermarket performance parts manufacturers usually hype their products through advertising, that's how they sell stuff.

The second thing to be considered, is many aftermarket parts list a HP/TQ raise, but what they don't tell you, is that most of the time this is based on a average or similar vehicle, most of the time their test vehicle is NOT the same as yours, and neither do most, if any, companies, have the resources to test every configuration and vehicle out there, so they test them on similar vehicles. Another thing to keep in consideration is that their test environments are usually made as ideal as possible for the test, i.e. best ambient air temps, etc.

Now time to move on.

Now consider, your vehicle is operating in entirely different conditions most likely than the AMPPMFR (aftermarket performance parts manufacturer, so referenced to from henceforth), even stuff like what engine oil, what spark plugs, etc. can directly affect how a aftermarket performance part will perform. And as everybody knows, your driving habits will directly IMPACT the effects that the part makes.

Next, are the designs good?

I will first attempt to shed some light on the subject of performance air filters, whether they are designed to replace the OEM filter as a drop-in replacement, or to replace the filter on a ram-air or CAI.

Many, but not all, aftermarket performance air filters have larger pores in the filter, essentially letting more air through, but also letting more dirt and grit in. I DID NOT SAY ALL FILTERS DO THIS, but many do.

From a independent test of various filters, here's the results. Please keep in mind, these are NOT my tests, and I do not know the conditions of testing, but I am posting it here JUST for comparison, and to put a different perspective on the whole subject.

Testing results for these air filters comes from nicoclub, original article viewable here: http://www.nicoclub.com/archives/kn-vs-oem-filter.html. I encourage you to read the article, and with a grain of salt.



This next photo tells how much dirt can accumulate BEFORE the filter cannot operate effectively anymore.



This one shows how much dirt passed through the filters.



How much of the above data is true? It will vary without doubt, but I believe that it is true to some extent. So keep this in mind. I always just buy name-brand filters, or OEM, in almost all cases they will be the best.

Now on to CAIs.

Do they work? I personally have NEVER owned a CAI, or driven a vehicle that has one, so I can claim some exemption from bias.

The short answer: Somtimes.

The above answer is very true. I have spent hours researching this subject,as I wanted to know if it really was worth the money.

After the time I spent reading up on the subject, I found there are two approaches to the CAI: They never work, or they always work. I found it very rare that anybody really took the time to ponder the subject.
Everyone will experience different results, and dyno results can sometimes be deceptive. The best case is someone who is happy with it, regardless of dyno tests. Many times it seems that people report no dyno changes, but a change in the feel.
So do they work? In general, research, certain vehicles were desgined with a very restrictive airbox, and in that case they can be a benefit, allowing the engine to breathe better. But where do they get their air from? If it's right inside the engine bay, it won't really be a "cold air intake", but it certainly will increase air flow.

Read this, original forum post can be found here, once again I encourage you to read the post: http://forums.vwvortex.com/showthrea...1#post27883761

In the above scenario, the guy took his air cleaner hose off, thus allowing the factory intake to suck air in from the same location as a CAI would. this is NOT a flow test, this is a temperature reduction test. The location the CAI draws air from
obviously is bad. Hence, WATCH OUT FOR WHERE THE CAI DRAWS AIR IN FROM, IF IT DRAWS AIR IN FROM THE ENGINE BAY IT IS ENTIRELY WORTHLESS TO KEEP INTAKE AIR TEMPERATURES DOWN! Not saying it won't increase air flow, but if you have studied physics at all,
remember that air becomes LESS dense as it gets hotter, meaning it expands, so you get less air for the same volume drawn in. So if the CAI DOES allow better airflow, but draws in hotter, less dense air, it could essentially just be giving the engine the exact same amount of air!

Now, lets think about the next problem with CAIs. We are going to assume that the CAI draws air in from a location outside of the engine bay, and that it does flow better than a factory intake. So the engine gets more air which means the engine is now capable of burning more fuel, which means more power.
Is the engine able to use this extra air effectively? It's up to you to decide whether or not the CAI actually does allow enough extra air into the engine to be able to develop any measuerable increase in power.
But with *******ly all of our engines, they are computer controlled. They do not take into consideration that the engine is getting more air, or for what the computer is really caring about, the engine got a few more cubes of displacement (figuratively speaking!)
THe computer doesn't know that, and it cannot really detect that on our Dodge trucks. A very little amount of extra air won't harm the computers thinking, but enough will cause the computer to be confused, because it thinks it has, for example,
a 360 ci engine. By increasing the airflow, you are (once again FIGURATIVELY, and EXAGERATED FOR CLARITYS SAKE!) essentially increasing that engine to a, say, 365CI. That is how the computer side of it all looks. But the computer doesn't look for extra displacment.
It was programmed form the factory to operate a 360CI engine, and has no accurate way to tell that increased unless you tell it by re-programming it to operate a 365CI engine. Granted, that litle bit of CI increase can probably be handled by the computer, because they wre designed with a little, but not much, room to variate.
But does the computer detect the extra air density? No.

What the computer sees is a lower IAT (Intake Air Temperature), and for the normal amount of fuel, a slightly lean condition. The computer CAN and WILL enrich the mixture a little bit, but it cannot enrich it much, and if it has to enrich it to the warm-up amount, it will set a error code, as it thinks a sensor is bad.
Do CAIs set error codes? Usually, no. But you are causing the computer to run on the border of it's control limits. Because the IAT is lower, it compares that against the ECT (Engine Coolant Temperature) to see if the engine is warmed up or not. If the ECT reads low, it will enrich the mixture to allow the engine to warm up faster.
Once the engine is warmer, the ECT will read a higher value (I'm not referring to the voltage, but the human readable degrees whatever), and since the computer reads a cooler IAT, it assumes it is running in (once again, stretched a little for perspective) a winter climate, so it causes the engine to run richer.
MY point is, it is throwing the computer out of balance, and while it may be able to run seemingly properly, it is on its limits of being able to control it, and a little change elsewhere could throw it to far out that it will go into "limp" mode.

You have heard the saying, every little bit makes a difference. That is very true, and by itself the CAI will do very little, but combined with other mods it has the potential to increase the effectiveness of the other mods, but by itself the CAI is probably not worth the money.

Our factory Dodeg intakes draw air from the fender, which is not affected a whole lot by a hot engine, so the air DOES come in cooler than a CAI that draws the hot air coming off of the radiator and engine. The factory air box really is more of a CAI than a so-called CAI!

As far as flowing air, a high-quality air filter in a factory air box will perform just fine and won't hurt the engine or performance, and even a mildly modded engine can still be handled by the factory intake.

So do I recommend a CAI for our Dodge trucks? What I say, there are better places to spend your money first. Things like 8.5MM spark plug wires, brass contact dist caps and rotors, high-quality spark plugs, good engine oil, a high-quality air filter,keeping good coolant in, basically
mainting the truck very well. This even includes seemingly unrelated items like changing differential fluid regularly with high-quality gear oil matching your operating conditions. Gear oil does wear out, and if it is worn even a little bit it won't lubricate as well, which increases friction,
heat, etc., and will actually decrease both the life and performance of the whole vehicle, even if not noticeable right now!

Do CAIs change the sound of the engine and exhaust? Probably, and if that is what you want and don't mind the other effects, by all means go for it!

What about ram-airs? Do they work? On our trucks specifically, I have no idea, but the same cautions apply as for CAIs, where do they get their air and how much extra do they push? I know many people put ram-airs on, with more benefits than CAIs. and personally I'd go for a ram-air any day over a CAI, but once again,
are they really necessary on a stock engine? For the money you spend on CAIs or ram-airs, you could have spent that in other more effective places.

I am NOT saying aftermarket mods aren't any good! I am just saying be careful where you place your money, as some things aren't worth the money! Things like exhaust will do more in the long run, and won't affect the computer as much, if at all. Most computers on gasoline engines
are not programmed to match factory exhaust. For the $125 I could spend on a CAI, I could have new dual exhaust put on or most of the way on, see my point? Dual exhaust is more cost-effective.

Another thing to be addressed with the use of a CAI on our trucks, is coolant flows through the plenum, and warms the air up, so is a CAI really effective then? If you are sucking enough air through, it might have a chance to get to the cylinders coool enough to make a difference, or there's a possibility, it might help the coolan stay cooler...

I'll ad more later, including some math calculations. This is a start.

 

On our trucks SPECIFICALLY, CAI is pretty much a waste of money. 99% of them draw air from the EXACT same place as the stock system, so, it isn't any 'colder' than the stock system supplies. There MIGHT be a slight advantage in flow at higher RPM, but, since our engines spend so little time there, its pretty much pointless.

Given that some of the systems cost north of 300 bucks....... you would be MUCH further ahead spending that cash on some good roller rockers. At least the rockers give you some real world gains across the RPM band. Or a tuner. Or a cam. Even long-tube headers and better exhaust would give you more.

CAI is a gimmick for us. Plain and simple. Rates right up there with throttle body spacers.

 

So I will squawk about this again...

V I R T U A L L Y

Is a word ************************************************** ****** out in my post above.

 

Awesome post tech!! Wealth of information in there! Lots of information in there I didn't know This is definitely sticky worthy IMO!

 

Mine had one when I bought it, does it help? Maybe, but I'd like to believe it does.

 

^BBartow, your's has much less chance of drawing hot air in from the engine bay, so that is not so much of a concern.

 

I shoved my stock air tube into the area behind the horns on mine.

 

^didnt you put it back?

 

Yeah, then I put it back to that again.

I especially can't put it back now without a clamp, bent just about permanently me thinks.

 

I lost my tube....fell off one day and melted to my exhaust manifold. so I'm running a hot air intake lol.