This may seem like a dumb question but are there any recommended air filters (or brands to definitely not use) for Cadillacs?

I ask this question because there is great debate on the Ford Truck forum (I have a F350 Superduty, V10 engine) on this subject, especially concerning the use of K&N filters (which I currently use). Some say the K&N is not as good as a standard filter in filtering dirt.

see http://www.ford-trucks.com/forums/showthread.php?p=1793360#post1793360

Thanks,

PeteC
87 Eldorado

I'm glad I didn't waste my money on air filters. The following article I found at http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=007856 confirms my suspicion.

Using a K&N filter won't hardly add any power and will only make your engine wear out faster. According to the article below, the K&N passed 15 times more dirt into the engine than the AC Delco. BUYER BEWARE!!

Here's the article:

On another diesel forum the members banded together to conduct an independent study regarding air filters for the Duramax Diesel. 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.

I saw that one too. Scared the heck out of me. I don't understand how the K&Ns (and others) can be that bad and not be tearing up engines left and right? I still plan to get rid of the K&Ns in my other vehicles. Unless someone has a better suggestion it looks like the ACDelcos are the way to go.

Thank you Edahall for your excellent summary.

Despite the claims of after-market filter vendors (which are ALWAYS shot down with objective testing) there are only two ways to make "more power" out of our engines with filters. One is to increase the surface area of the filter to decrease the pressure drop of the air as it flows through. The other is to lower the temperature of the incoming air.

To get much appreciable gain a significant plumbing problem is almost always created because of limited underhood space.

I'm glad I didn't waste my money on air filters. The following article I found at http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=007856 confirms my suspicion.

Here's the article:

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

.

This is interesting. I have a Amsoil video tape on a flow bench showing that the Paper element (fram I think was the filter) was a higher flow restriction, next was the K&N and slightly better than that was the Amsoil filter (forgot actual model, but I can watch it again). No trickerly, just actual numbers on a standard flow bench that you would port cyl heads on.

Question: Was each filter out of the box, or was it oiled first? The Amsoil comes oiled, but is often overoiled by users, which will cause flow restriction. And always should be checked even out of the box to ensure not too much oil is on it. Same with any oil wetted filter.

Would be nice to know more details to the test. Anyone know?

Tom

On the 4.1 and 4.5 I have always used the AC Delco or Fram (it depends on how much $$$ I had at the time). But that is some interesting info.

It would be extremely unusual for a simple air filter element replacement to give a performance increase. The air filter element is not the restrictive part of the system if it is designed correctly and most any OEM filter is sized so that it can still provide adequate performance even when very dirty....so....claims of performance improvements by replacing an air filter element with an aftermarket part are greatly exaggerated.

Use the OEM style paper element and spend the extra money on buying a fresh one occasionally.

if you want a little more performance, go for a custom cool air induction. a change of the filters while in the stock box will do nothing more than bite the wallet for more money than you need to spend. the stock air box is the weakness so to speak, not the filter.

if you want a little more performance, go for a custom cool air induction. a change of the filters while in the stock box will do nothing more than bite the wallet for more money than you need to spend. the stock air box is the weakness so to speak, not the filter.

time to hook up a MAP sensor on the iintake, before and after the filter and measure restriction (if any) real time.

I'll have to look and see if I can get some sensors, or have any. That would be interesting to know. IF there is any at all.

I agree, a properly designed system is key. I feel most are. And if you have one that isn't, a high flow filter may not be best for air quality, so more surface area is next step, not an easier flowing one. Like the old days, take your old 14in round air cleaner and stick a 5in element in place of the 3 in. 66% more flow, same filtration quality. (hint, you 4.1 RWD guys, get the Olds Diesel air cleaner, and use the factory 5in high 14in element!!)

When I get it tested I will post results!


Tom

i hope you're not implying that im full of shit. when i hooked my custom intake, albeit not in the coolest area of the compartment, i did have some noticeable gain on acceleration. do what you want with the MAP sensors...i know what im doing, and it works.

i hope you're not implying that im full of shit. when i hooked my custom intake, albeit not in the coolest area of the compartment, i did have some noticeable gain on acceleration. do what you want with the MAP sensors...i know what im doing, and it works.

No not at all! I have had so many people try to claim that you NEED backpressure to have good power. The comment was not directed at anyone. I appologize if it seemd that way. It (backpressure) is one of those myths :lies:. Typically the problem with losing power with a highflow exhaust of some sort is often led to a backpressure EGR. It uses the backpressure to improve EGR modulation so it will be more responsive and work better. But if it is now messed up from factory calibration, it can actualy then hurt performance.

It sounds as if you are on the right track to getting the Cad to make some good power. Have you run it at all down the 1/4mi?

Tom

No not at all! I have had so many people try to claim that you NEED backpressure to have good power. The comment was not directed at anyone. I appologize if it seemd that way. It (backpressure) is one of those myths :lies:. Typically the problem with losing power with a highflow exhaust of some sort is often led to a backpressure EGR. It uses the backpressure to improve EGR modulation so it will be more responsive and work better. But if it is now messed up from factory calibration, it can actualy then hurt performance.

It sounds as if you are on the right track to getting the Cad to make some good power. Have you run it at all down the 1/4mi?

Tomare you talking about exhaust or the intake??? now i feel like an ass. sorry. i ran 15.38 @91 mph last fall at the local strip. 6.8 0-60 according to a borrowed g-tech. honestly though, the car is starting to show her age...
:crying: . what with 145k on the od, i think she is getting closer to the planned rebuild. i just need to finish my 87' seville first.

as far as the backpressure goes, i have very little on my car, a gutted cat. converter and a 40 series flowmaster seems sufficient to me. i have plans to quiet the car one day, but after i rebuild the 4.9 motor. the reason i have tried to keep a little backpressure on the car is because of the stock EGR system. seemed to me at the time if i go and change things too much, i may hurt, not help performance.

again, sorry for being an ass...:worship: illuminaP :cool:.

A note that I didn't see commented on in the test the guy did with the leaf blower.

300 CFM is airflow. So if the worst paper filter is 10 inches water restriction (was that the value? I forgot) at only 300 CFM, that is pretty high.

Does that sound as bad to everyone or just me? So what is it at 600 CFM, an approx redline airflow that could be expected in a 4.9L (ok, maybe a little high), what is the restriction?

I guess what I would think is to monitor O2 voltage on the diag display and see what the value is at WOT close to high rpm shift points. If the value starts to drop lower, say below of 0.8v and dropping increasingly, I would think it is suggesting that the air filter, or something in the intake airflow tract is hindering sufficient supply of O2 to the engine. So if anyone has time to do some acceleration runs and likes to beat on the Caddy, and has a high flow filter and would like to do some comparisson of a paper filter and the high flow, I would love to see the comparisson.

Reason for watching O2, if the value is below .9, it will be increasingly getting lean for making max power. Remember, .45 is 14.7, but at .55, is not 15.5, but more like 14.75 to 14.8. It is a very high resultion at the .85 to .15 volt range, so the ECM can react best. The Wideband O2 sensors are more what we want to see on our cars. But they are $$$. And not compatible with the current ECM programming. But a Wideband O2 can operate at room temp, giving you closed loop operation at engine start.

Tom

A note that I didn't see commented on in the test the guy did with the leaf blower.

300 CFM is airflow. So if the worst paper filter is 10 inches water restriction (was that the value? I forgot) at only 300 CFM, that is pretty high.

Does that sound as bad to everyone or just me? So what is it at 600 CFM, an approx redline airflow that could be expected in a 4.9L (ok, maybe a little high), what is the restriction?

I guess what I would think is to monitor O2 voltage on the diag display and see what the value is at WOT close to high rpm shift points. If the value starts to drop lower, say below of 0.8v and dropping increasingly, I would think it is suggesting that the air filter, or something in the intake airflow tract is hindering sufficient supply of O2 to the engine. So if anyone has time to do some acceleration runs and likes to beat on the Caddy, and has a high flow filter and would like to do some comparisson of a paper filter and the high flow, I would love to see the comparisson.

Reason for watching O2, if the value is below .9, it will be increasingly getting lean for making max power. Remember, .45 is 14.7, but at .55, is not 15.5, but more like 14.75 to 14.8. It is a very high resultion at the .85 to .15 volt range, so the ECM can react best. The Wideband O2 sensors are more what we want to see on our cars. But they are $$$. And not compatible with the current ECM programming. But a Wideband O2 can operate at room temp, giving you closed loop operation at engine start.

Tom


as far as a drop-in air filter, no, you will not gain much power if any. my point is to design an open element air intake system from a cooler area away from the engine. even my short ram intake will gain a little improvement because of the open element design (i am trying to design a cooler area though). a ram air system would be optimal for more gain.

as far as the k&n drop-in replacement, i too don't see how you can realy gain anything for flow. you are still using the stock air box system that car came with. if performence is not your deck of cards, a puralator paper element will suffice. and you will save too.

the focal point in sales for the k&n drop-in's are the fact that they can be cleaned and re-used: after you spend another 15 dollars to buy the cleaning kit.

Got nothing to do with cadillac but......I pulled my K&N out of my bike when I saw this.

A dyno test was done on a 2000 CBR 929RR motorcycle.

1. With a K&N filter.
2. With OEM Filter.
3. WIth No filter.

Heres the results:

We ran the following tests regarding air filters on a stock 929 with OEM exhaust, Hindle bolt on and Hindle full system:

OEM filter 3 runs:

OEM Exhaust best run: 121.5
Hindle bolt on best run: 124.0
Hindle full system best run: 133.5

K&N 929 replacement filter:

OEM Exhaust best run: 119.0
Hindle bolt on best run: 121.0
Hindle full system best run: 129.5

"Whacked" filter (all paper removed, both screens remained)

OEM Exhaust best run: 124.5
Hindle bolt on best run: 127.5
Hindle full system best run: 137.0

These test were run on 108 Octane Sunoco "pump" race gas on a DJ 250 and were made without any third party fuel management system (i.e. PC111 etc.) The test site is 530 ft above sea level and all readings are SAE sea level temp and pressure corrected from "actual" 80 degrees ambient temp and 74% relative humidity.

The same set of tests run on Torco Stealth 14 followed almost identical curves, but yielded an average of 3 additional HP except for the full system with the "modified" OEM filter which produced 144 to 146 HP in 12 consecutive runs.

Pair system was removed (and sealed) while the flapper was IN during all tests.

Any theories on why the K&N performed worse?

disturbed airflow to the carb or fuel injection?

Hmmm, got me wondering....

Filter over oiled and causing restriction? Dunno....

I'm not in any rush to buy a K&N at all for my 96 Suburban now.....

Any theories on why the K&N performed worse?

disturbed airflow to the carb or fuel injection?

Hmmm, got me wondering....

Filter over oiled and causing restriction? Dunno....

I'm not in any rush to buy a K&N at all for my 96 Suburban now.....


It simply does not flow as much air as stock. At least for that motorcycle. The K&N may be beneficial in some applications but I doubt it.

Another thing to be careful of is the oil used to lubricate the k&n has been linked to MAF sensor failure. I ran a k&n for awhile, then I had the MAF sensor malfunction. Replaced the MAF sensor (NOT A CHEAP PART!!!) and put a oem filter in. Its too pricey to replace MAF sensors.... :crying: