Purpose of a Cold Air Intake?

[4xFUN]

I installed the Mopar CAI but have not yet cut the vent in the hood...So far I like it, just as quite as stock at idle and cruising but you do know it's there when you get on it. I am waiting (not patiently) for Borla to release their 2-door Touring Climber cat-back. (As of today, they are thinking late September / early October) Once the exhaust is installed, I will add the Livernois 91 octane tune and feel confident this combo will be a worthwhile performance improvement.

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[Go Outside]

My intake has gaskets that route the incoming air through the grill and body work. It is not as if this is an old car with an air filter perched up on top of the engine drawing air from the engine compartment.

 

[Whaler27]

Waste of money. On a naturally aspirated V8 they might give you a gnarlier vroooom sound, but that’s it. They can cause issues (water/dust ingress), and are a bad idea.

On a V6 or Turbo 4cyl, you’re not going to get a gnarly vroom sound no matter what. Even if you slap an expensive catback exhaust on there it’s going to sound, at best, like one of those “stanced” Acura/Honda shit boxes that buzz around like mosquitoes.

That’s my not so humble opinion.

X2

I installed CAIs on the three big diesel trucks (two Fords and a Dodge) we used to haul boats between 1995 and 2010. I was convinced they helped With power and fuel economy, probably because I ignorantly bought into the marketing hype and we always installed them at the same time we installed tuners that changed fueling rate and turbo boost. Then I read a fantastic research project produced by a retired engineer on one of the diesel truck forums. He did extensive research, including calculations on the amount of air required to optimize combustion/performance, the flow rates permitted by seven or eight aftermarket filter/intake systems, and the particulate size that could pass through each of the filters. He also did extensive dyno testing and included all of the results. In the end, the factory air filters and the aftermarket clones were the best. The CAI claims were almost complete hogwash. I say almost because there was a fuel burn rate at which more air would be required than the factory air filters would permit, but those fueling rates would only be seen with engines that were producing crazy amountS of horsepower. I can’t remember what the Exact number was, but I remember it being over 750 horsepower. For the remaining 99.9% of the CAI sales, although customers (like me) thought they were getting better performance, they almost never were.

Now the new diesels from the big three manufacturers ALL make more horsepower and torque than my trucks that we chipped, piped with 4” exhaust, and attached CAI to twenty years ago, and they all have paper filters that provide superior filtration and protection for the engine.

I’ll try to find that post, if it’s permissible to link it here.

 

[Whaler27]

I found another more recent air filter test I remember reading a few years ago. It doesn’t provide all the performance detail the other one included, but provides great information on the efficiency of the filters and the protection they provide (or don’t provide).

Google “air filter comparison diesel bombers”.

The independent research shows that most of the aftermarket CAI systems allow more dirt to pass, get dirty/overloaded more quickly, and do nothing (or worse) for performance.

 

[Whaler27]

Okay, Although these tests were performed on air filters sized to fit the Duramax diesel, you’ll recognize technology/brands hyped for wranglers.

The tests were done on a $285,000 air filter testing machine made by Testand Corp. This is a machine that controls all variables including airflow, temp., humidity, dust feed rate, dust temp. and humidity, etc...and then weighs all components (filter, post-filter, test dust) to 1/1000 gram.

The filters tested were the brands listed below.

NONE of these aftermarket air filters will add power. NONE! They look cool, cost a lot and add dirt to your oil. If you are good with that then stick with them. (quoted from Spicer, the author of the report. Test results below.)

 

[Whaler27]

“There is a lot of marketing hype surrounding certain aftermarket air filters and we wanted to know if the filters could stand up to their claims. Claims of "superior" filtering ability and dirt holding capacity are among some of these claims. Additionally, many filters are claimed to allow for "better" air flow giving you more horsepower.

This claim of better flow giving more horsepower is a debate all its own, but dyno tests run with a paper filter vs. NO FILTER AT ALL have shown NO INCREASE IN POWER OUTPUT. Therefore a filter with "better flow" will not only give you no increase in performance, it will also let in a lot of dirt while doing it.

The following data is provided by Testand Corp. in Rhode Island. Testand makes the $285,000 machines that perform the SAE J726/ISO 5011 air filter test standard. Any air filter that wants to be tested for performance and efficiency uses this test. These tests cost $1,700 per filter when done by an independent laboratory. Testand Corp. was interested in the comparison study and agreed to do the study for us.

Every filter listed was tested in an identical manner according to the SAE/ISO test standard> Here are the results:


In the order of EFFICIENCY (ability to filter dirt) the results are as follows:

FILTER % EFFICIENCY

AC Delco OE 99.93%
Baldwin paper 99.72%
No name pargain paper 99.32%
AFE Pro Guard 7 panel filter 99.23%
WIX/Napa Gold 99.03%
Purolator paper 98.73%
Amsoil, new style 98.63%
UNI 97.93%
K&N 96.80%


FLOW RESTRICTION from best to worst. Remember, 27.7 inches of water = 1 psi. So, 1 inch of water = .036 psi. The worst (AC Delco) at 6.23 in. water and the best (K&N) at 4.54 in. water is a difference of 1.69 in. of water or a "whopping" .0608 psi. Virtually negligible.

In order from least restricive to most:

FILTER RESTRICTION in inches of water

K&N 4.54
Mystery bargain 4.78
AFE Pro Guard 4.99
Purolator 5.05
WIX/Napa Gold 5.06
UNI 5.40
Baldwin 5.71
Amsoil 5.88
AC Delco 6.23


DIRT HOLDING CAPACITY. From best to worst. This is the AMOUNT of test dirt it took to create an ADDITIONAL 10 inches of restriction. At that point the test is terminated. This is an indication of HOW LONG a filter is good before it must be cleaned or replaced.

FILTER Dirt Holding Capacity

AC Delco 573.898 grams
WIX/Napa Gold 447.366 g
Purolator 388.659 g
Baldwin 388.154 g
UNI 374.638 g
Mystery bargain 350.402 g
AFE Pro Guard 7 232.516 g
K&N 211.580 g
Amsoil 196.323 g


TOTAL DIRT PASSING THE FILTER DURING THE TEST. This is how much dirt your engine will take in if you use the filter for the duration that would cause the filter to become "dirty" enough to need replacement or cleaning. The "Dirt Passing The Filter" is the dirt collected by the "POST FILTER" during the SAE/ISO test.

In order from best to worst, the filters performed as follows:

FILTER DIRT IN GRAMS PASSED

AC Delco 0.4g
Baldwin 1.1g
AFE Pro Guard 7 1.8g
Mystery bargain 2.4g
Amsoil 2.7g
WIX/Napa Gold 4.4g
Purolator 5.0g
K&N 6.0g
UNI 7.9g

NOTE: During the test the Purolator was reported to have had a seal failure which gave it higher than expected dirt passing.

None of this should be a surprise. Ford, GM, and Chrysler spend millions and millions of dollars researching how to improve fuel economy, horsepower and torque. If all these objectives could be achieved by swapping for a more porous air filter one of they would have figured it out long ago (or bought one of the original companies that started the hype, like K&N.)

Thanks to Spicer for putting all this together. I’ve purchased seven or eight trucks and Jeeps since this research was done, so he’s saved me a LOT of money.

 

[BrntWS6]

I am not all that worried about a bit more dirt getting through, within reason. I don't like filters you have to oil. But a good oil filter will catch it a lot.

This does not test the effectiveness of a CAI though. Which I will admit the gains are usually minimal, maybe 10hp in the upper rpm range. Personally I don't think that is bad at all. Some are better than others of course. The reason manufacturers don't offer more efficient designs from the factory is because they have to keep the sound level down. Most people want their cars quiet.

There is a kit for my Trans am called the BG ram air. Gains were 20hp and 2 tenths in the quarter mile. Dyno and track tested by GMHTP magazine. I personally saw a MPG increase with my Mopar CAI after I installed the hood vent.

 

[2020Sport]

That seems to be a 2004 study. Here is a 2012 study with the newer filters. https://www.gmtruckcentral.com/articles/air-filter-study.html

 

[Whaler27]

That seems to be a 2004 study. Here is a 2012 study with the newer filters. https://www.gmtruckcentral.com/articles/air-filter-study.html

Good find — and similar results! I’ve yet to see any independent testing that shows aftermarket filters or cold air intake systems make any favorable difference in performance In low horsepower systems, but it’s clear they allow more grit into your engine. In retrospect I feel very foolish for buying into all the hype with my trucks — but I’m definitely not alone. In 1990 there were only a handful of manufacturers selling these things, but everybody and their dog manufactures them now. Millions of dollars are spent on them every year — which is why Mopar has gotten into the act. Apparently the marketing guys and accounting guys ganged up and won the wrestling match with the engineers.

 

[oldcjguy]

This claim of better flow giving more horsepower is a debate all its own, but dyno tests run with a paper filter vs. NO FILTER AT ALL have shown NO INCREASE IN POWER OUTPUT. Therefore a filter with "better flow" will not only give you no increase in performance, it will also let in a lot of dirt while doing it.

This is not necessarily true. it will make a difference and show more hp/tq IF the filter was the source of a restriction. In jeeps the engines are too small and the factory intakes are large enough to be able to supply what ever amount of air the engine requires. This is also true of cold air intakes themselves. If the tube design is better than factory you may see an increase. That's not always something that will be measured on a flow bench. There are intake air temp sensors in the intake tubes. If the tube design keeps the air cooler than the factory AND the air coming in through the factory tube was hot enough for the computer to start pulling timing then the cold air intake will result in a more HP than factory. Not because it add more but because it did not cause any to be subtracted.

Me, I'm keeping the the factory style filter. I'm not after peak hp numbers anymore. That's not what I need in a jeep. I may add an inter cooler pipe (2.0T) as it is more efficient throughout the rpm range, but I don't think I'll be changing the intake. Not with a "high flow" filter at any rate. I'd rather sacrifice the flow for cleaner air. Especially since I don't believe air flow for a whopping 2 liter motor is going to be an issue.

 

[Shots]

I get the science behind a cold air intake, but after having put one on a few of my previous cars, I saw a barely noticeable difference in fuel efficiency, horse power gains, etc., and more often than not, the claims that the manufacturers made weren’t very accurate. Just my two cents...

On older vehicles with carborated engines, they could show you more improvement than they do on fuel injected engines. On the carborated engine the a CAI could change the air/fuel ratio by introducing more oxygen to the mix. Modern engines are constantly adjusting based on sensors in the intake, exhaust, etc. If the CAI does introduce more oxygen into the system, the fuel injection system will simply add more fuel, thereby keeping the air/fuel mixture the same as it was before. You may get a small bump immediately after installing it (which I doubt), but it will balance again shortly thereafter.

Claims of horsepower are nonsense, if it added any it would be such a small amount that it would not be noticeable.......

This is absolutely correct. Keep in mind that even if they were to produce the advertised HP they're talking about peak HP. This isn't an across the board boost.
To simplify it, lets assume they could give you 20 hp which is the boldest claim I remember seeing. You can achieve this same effect by reducing weight, and studies have proven that cutting weight saves fuel.
Stock = 4100 lbs / 285 hp = 14.38 lbs per 1 hp.
Modded = 4100 lbs / 305 hp = 13.44 lbs per 1 hp.
Lightened = 3830 lbs / 285 hp = 13.44 lbs per 1 hp.
Notice the modded, and lightened have the same power to weight ratio? So all you have to do is tell you 270 lbs buddy to get out. Or you could be nice, let him ride, and drop some of the unnecessary weight. The best part is cutting weight is usually free, whereas the CAI will cost you money.
Anyway the point is, you're not likely to feel any of the reported gains. After all do you feel a loss of power when you have 2 passengers (or 1 fat one)? Probably not. The 20 hp bump will feel the same. so any gains are extremely minimal.

Waste of money. On a naturally aspirated V8 they might give you a gnarlier vroooom sound, but that’s it. ...

That's pretty much all they're good for. I too bought into the hype with my trucks. Then I did the engineering/math on it myself and I figured out that they weren't doing much good, if at all. Any savings in fuel efficiency was so minimal that it would take years to offset the cost of the CAI system, and the power gains were nothing I was going to feel. You can spend money on more effective items like tuners that can change shift points, fuel mixtures, etc and get better results.
FWIW, the CAI did sound pretty cool on my V8 Ram though.

 

[2020Sport]

On older vehicles with carborated engines, they could show you more improvement than they do on fuel injected engines. On the carborated engine the a CAI could change the air/fuel ratio by introducing more oxygen to the mix. Modern engines are constantly adjusting based on sensors in the intake, exhaust, etc. If the CAI does introduce more oxygen into the system, the fuel injection system will simply add more fuel, thereby keeping the air/fuel mixture the same as it was before. You may get a small bump immediately after installing it (which I doubt), but it will balance again shortly thereafter.



This is absolutely correct. Keep in mind that even if they were to produce the advertised HP they're talking about peak HP. This isn't an across the board boost.
To simplify it, lets assume they could give you 20 hp which is the boldest claim I remember seeing. You can achieve this same effect by reducing weight, and studies have proven that cutting weight saves fuel.
Stock = 4100 lbs / 285 hp = 14.38 lbs per 1 hp.
Modded = 4100 lbs / 305 hp = 13.44 lbs per 1 hp.
Lightened = 3830 lbs / 285 hp = 13.44 lbs per 1 hp.
Notice the modded, and lightened have the same power to weight ratio? So all you have to do is tell you 270 lbs buddy to get out. Or you could be nice, let him ride, and drop some of the unnecessary weight. The best part is cutting weight is usually free, whereas the CAI will cost you money.
Anyway the point is, you're not likely to feel any of the reported gains. After all do you feel a loss of power when you have 2 passengers (or 1 fat one)? Probably not. The 20 hp bump will feel the same. so any gains are extremely minimal.

That's pretty much all they're good for. I too bought into the hype with my trucks. Then I did the engineering/math on it myself and I figured out that they weren't doing much good, if at all. Any savings in fuel efficiency was so minimal that it would take years to offset the cost of the CAI system, and the power gains were nothing I was going to feel. You can spend money on more effective items like tuners that can change shift points, fuel mixtures, etc and get better results.
FWIW, the CAI did sound pretty cool on my V8 Ram though.

I’ll likely upgrade to the Amsoil filter as it passed 4-60 times less dirt than the other 11, holds more dirt, needs no washing and oiling, and is reusable to 100,000 miles.

 

[oldcjguy]

I’ll likely upgrade to the Amsoil filter as it passed 4-60 times less dirt than the other 11, holds more dirt, needs no washing and oiling, and is reusable to 100,000 miles.

You may want to re-read the chart in the post above. The Amsoil filter held the least amount of the filters tested and filtered 7x LESS dirt than the AC Delco. I'm a fan of their oils, but I won't be using there filter unless they have something comparable to stock.

 

[2020Sport]

Oldcjguy, I think you are looking at the data from the 2004 report that tested an old obsolete AMSOIL oiled foam filter. Their current dry synthetic nano fiber filter evaluated in the 2012 report I linked had by far the best filtration of the 12 filters tested, and a huge improvement over stock. https://www.gmtruckcentral.com/articles/air-filter-study.html

 

[TxJeepers]

Waste of money. Supercharge or go home.

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