Air Cleaner
 

Now that K&N are officially approved by the coastguard I've got a question, what one to use? I got a couple motors in a boat (Kiekhaefer 482's) that has feet of clearance above the motor. Got me thinking about different air cleaners like the 9" or the 14" or a velocity stack style. Any ideas?

Have a look at this thread, with info provided I wouldn't use one
http://www.offshoreonly.com/forums/g...n-my-shop.html

Big difference between a giant full size one and a little tiny one they sell for the 502 MPI I would not be afraid to use a full size one on top of a motor

I had an 8" by 2" tall on my old small block. It ran identical speeds (GPS) with or without the K&N. Choke horn milled off the Holley carb.

I'm considering another for my current build as I'm limited in verticle space. My buddy talked to one of the race teams at key west and they were running a K&N.

I'm thinking that the more area of filter media is better. Wether you get the area from more diameter or a taller element probably doesn't matter. The critical design feature is a nice radius in the base plate.

Haven't they been used for a long time? My 500efi's have them and they are 2000's so im a bit confused

Been available for at least 10 years

I will add this, I built and dynoed a 462 ci pontiac that made between 570-580 hp day to day, a kn 3x9 took it down to high 530s, low 540's. a 14x4 element paper or kn didnt change it enough to measure. a 3x14 cost 6-9 hp. You want as much area as possible, buy biggest one that will fit if your making over 500 hp, Smitty

That 3x9 K&N only flows about 500 CFM. 3x14 is 800 CFM. 4x14 is 1050CFM.

Really good to know. Thanks all.

bet you won't see any K&N's on K&N challange cars !!!!

so, K&N filters are now CG approved spark arrestors?

Not all of them. Just the ones that are "marine flame arrestors". They have been available for over a decade and carry the proper identification as such.

Correct.

Here is the FA section: http://www.knfilters.com/marine/boats.aspx

Thing that stinks even with their round FA's, you cannot purchase just the element when the time comes you want to replace them. You have to buy the complete assembly.

People think K&N's are lifetime. Well, they are not. They shrink over time ! Yes, seen this happen many times in my professional and personal life's. Doh !

And yes, I would use a 14" x 4" element on the motor in question. If you want to go larger, that is fine.

I have not seen positive dyno runs with the Velocity Stack assemblies.

The 9X4 assembly has a 2.75" element height and I have a mid to upper 300hp small block motor in very light weight boat that loses almost 2mph with this assembly. The Demon carb installed does have a choke tower.

Anyone have numbers on the metal flame arrestors? One better ten the other. Just looking for the best options.

That velocity stack w 3x9 element was the hp killer in our dyno testing, we also clamped the element and lid on full size base to see IF it was the velocity stack or elent, it was the element that killed hp, too small of area

Not too off topic. What's available with a dominator base?

A decent amt.

If the arrestor doesn't come out and say it's for a Dominator (4500 style) carb, look for 7-5/16” flange diameter.

Good to know thanks. I'd like to get one of the nice radiused k/n bases and put an arrestor style top screen on it

The ones on my 500efi's look like they are collapsing/shrinking and was wondering about that. Maybe if that was restricting air flow. I guess its time for new ones. The 525's seem to be bigger will they would on my 500's?

Yes, the K&N's shrink over time....and yes it is restricting some airflow.

I have one here that has shrunk more than anyone can believe, until I show them.

I have had k&n for years in automotive apps and haven't experienced the shrinking yet. These are all the modern rectangular shaped ones I'm using. Are you using the k&n cleaner/oil?

Hmmmm. Well, keep driving then. LOL.

BTW: More common to have a 10yr old K&N on a boat, then a car.

I just picked a number, but it should work.

Don't use the filters or cars anymore. I still have a truck with a K&N that I haven't even started in 3 yrs. Filters at least 10 yrs old. I'll pull it out and see how it looks.

I only have 1 customer that won't let me throw their K&N out. Bunch of years ago I noticed I was replacing more MAF's on vehicle's with K&N's and then I made a stand and got rid of them....Again, on MAF vehicles...especially those where the filter is close to the MAF. I continue to use them here and there on some carbureted engines.

I have one on my boats because we are on dirt roads that turn to dust roads during the summer. Boat get's put back on trailer each use, and gravel dust is very coarse !

Tell me about it. I live on gravel roads. Almost not even worth washing the car. Covered with a layer of dust every time I leave home. They do oil some of them a couple times a year, lucky me.