K&N OEm replacement air filter - Diesel Forum

capt324 · 07-04-2009, 11:39 AM

I have a NA 7.3 and want to get more air to the motor. I have not been able to find an aftermarket cold air intake kit but I did modify my existing air cleaner housing and have two tubes running to the front of the engine compartment. I am trying to decide wether to put cone filters on the ends of the tubes and leave out the filter in the stock housing or just to leave the tubes open and replace the stock air filter with a K&N OEM replacement. Anyone have any input on what would be better? Thanks

88beast · 07-04-2009, 01:38 PM

ok buy an air cleaner for a sbc motor from advanced or napa and buy that kandn filter for it just get one with the 4inch hole that simple ive seen it a few times on these engines
its smaller than stock and looks better then you dont have some half done modded air box to get better air flow when the stocker can flow more than the motor needs

CDX825 · 07-04-2009, 06:27 PM

Cone filters are not all cracked up to be. They have less surface area then the stock filter and that equals less flow. You would be better off with the k&n than a couple of cone filters.

94_turbo · 07-04-2009, 08:36 PM

K&n--n E V E R!!!!!

Richter69 · 07-05-2009, 12:44 AM

Hey now! Them K & N's work pretty good on a drag car...............

Keep the rocks and such outta the throttle blades.............

caryt · 07-06-2009, 04:29 PM

Gas motors..fine, never a diesel.

JASTECH · 07-06-2009, 08:18 PM

caryt, Why not? If they flow more air then the stock filter that is what Diesel's need most is air correct?

So now I am confused, I also have been told it is the best for a Diesel.
I will keep eyeball set aside for this thread, lol

Thanks, JASTECH

asauer · 07-06-2009, 09:19 PM

Our 7.3s consume much less air than small block gas motors that see high rpm.
I second the K&N naysayer- I would never put one on my vehicle.
It's a matter of physics- if the air filter stays the same size, but somehow can flow more air, something has to be traded off. That something is filtration.

94_turbo · 07-06-2009, 09:20 PM

K&N SUCKS. dont care what those pukes advertise---look up what some independent airflow tests show. the average flow diff is less than 2%. so what--you can damn near throw a rock thru them. one of them damn things tore the rings out of my 94 turbo. there were a lot of threads on this forum some longer time ago about guys having the same thing happen to them as me. and just try and prove your case if your engine gets ruined--fat chance!!!! they are a large could care less company--your a small peon---. your truck

BuilderBob · 07-06-2009, 10:07 PM

I have a K & N, no problems, on the other hand, there was no gain in performance.

LMJD · 07-07-2009, 08:49 AM

Quote:

I have a K & N, no problems

Me too, been using one for at least 15 years in the same truck. I'm 9000 miles short of 1/4 million miles and don't use any more oil than the first year when I bought the '91 truck new. Matter of fact, the only time I ever even had the valve covers off was to retorque heads at 30,000 when I installed my ATS turbo kit. Cleaned and oiled PROPERLY they do a great job of filtering. I spent 18 days as a chase truck on a major forest fire and the logging roads and USFS roads were so ground to dusty powder from all the heavy equipment we were ordered to run with our headlights on. After that mess was over when I cleaned my K&N I couldn't find even the slightest trace of anything that got by the filter in the intake ducting.

Quote:

there was no gain in performance

I can understand that. The reason I went to one is because the ATS turbo airbox is a little on the small side and with a brand new paper filter under a load I'd show 3" on my filter restriction gauge. Zero restriction with the K&N as long as I clean it every 13-15K.

Quote:

if the air filter stays the same size, but somehow can flow more air, something has to be traded off. That something is filtration.

Not really. It's a different filtering media that allows more flow, that doesn't mean it can't filter just as well. I'm fairly sure the all the Banks Sidewinder kits (plus air intake kits) come with a K&N, and with the many many Banks Sidewinder members here, if the filters didn't do the job they be lined up 50 deep posting threads condemning them.

Quote:

Our 7.3s consume much less air than small block gas motors that see high rpm.

Not true if it's turbocharged. Any factory engine rep will tell you a turboed engine draws in 3 time the air of a comprable displacement non-turboed engine, gas or diesel.

caryt · 07-07-2009, 12:58 PM

A ATS turbo on a IDI doesn't produce enough boost compared to a PS. Not enough to pull the sand-duct through a K&N style filter..just like a gas motor. Stick your hand in the intake track of your K&N..unless your very lucky you will feel sand. Do a oil analysis and you will see silica.
Bottom line not a single big rig uses anything but a big Donaldson type filter..its cause they work.

FYI every clean room made uses filters very similar to these..never a oiled filter.

BoostedBug · 07-07-2009, 01:06 PM

MY PS has 245k miles on it and has had a K&N in it from 1997 at 25k miles.. Never a problem as I am the third family owner since new..

My buddys dodge went from 20mpg to 17018mpg when the service shop put in a stock filter a few months ago and he did not have a recharge kit.. needless to say the K&N is going back in..

The main reason a big rig runs those throw away dry filters is that when it is time for maintenace they do not take the time to wash and clean and dry then oil a filter.. they get turned around and put back on the road..

They make no money sitting still.. Say what you want... A k &N works.. and last..

LMJD · 07-07-2009, 02:16 PM

Quote:

The main reason a big rig runs those throw away dry filters is that when it is time for maintenace they do not take the time to wash and clean and dry then oil a filter.. they get turned around and put back on the road..

Holy Crap, yes. Can you imagine how many hours it would take to clean two dual filters the size what's used on a heavy truck if they were K&Ns?

It takes me way over an hour to clean my little flat pickup size K&N. The cleaner gets the trapped dust/dirt out quick enough, but the bugs, bug wings trapped in the pleats give me fits. I keep an extra in stock so I can stick it in and clean the dirty one when I feel like it.

asauer · 07-07-2009, 07:30 PM

85% efficiency
444 cubic inch = 415CFM
3800RPM

85% efficiency
350 cubic inch = 603CFM
7000RPM

Now, this is for naturally aspirated motors, and is just a rough guesstimate. But even with a boosted 7.3L, 14.7psi (two atmospheres of pressure, higher than our 7.3s see) would net you around 830CFM. That would be about on par with a naturally aspirated big block...I am not saying I'm anywhere close to accurate on the turbo'd 7.3 figure- I couldn't find much about flow rates of turbo motors. I know the volumetric efficiency would be much higher than NA, but oh well. You get the drift.
Keeping engine displacement and VE the same, doubling the RPM requires double the airflow. Seeing as our diesels hardly can be considered high RPM or boost machines, I would feel safe saying that fancy air filters will do nothing for you. More important things to me would be the temperature of the air and the filtration...