What makes a flame arrestor?

[Top-Gun]

Sorry for the basic question, but whats the difference between a flame arrestor and a regular open element air cleaner? I ask as I'm looking for a performance air cleaner for a carbed 454 Magnum, and after looking at the K&N performance flame arrestors I don't see the difference between them and a plain old 14x3" performance filter? Is the filter medium different?

I have a nice spun aluminum 14" air cleaner lid and a drop base, I'm wondering if I could use these and just get a proper marine filter insert or is there more too this?

Thanks

[Pismo]

Use screening to build the element.

[Top-Gun]

By screening do you just mean a fine metal mesh (assume stainless would be ideal)? Could I just put some of this inside a plain old K&N element?

Thanks

[BlownCrewCab]

A Flame arrestor won't be damaged by a small fire, a gauze, paper, cotton, etc filter will actually add to the fire by being a fuel it's self, a flame arrestor wont burn.

[maddad]

I recall it being said that the K&N's with the metal mesh outside were OK with the C.G.

[Top-Gun]

From my research the only vendor I've been able to find offering a conventional 14x3" flame arrestor is K&N, and the filter element looks just like a normal one. Maybe the mesh is fine and I'm just not seeing it.

I just want to be sure whatever I use is safe, I've had plenty of through carb backfires on performance car motors and never had one catch fire, but can't be too safe.

[MOP]

Why not drop K&N an email, they may have the solution.

[silverghost]

About 5 years ago a frend with a 1960 Corvette had an engine backfire set his fibergass hood on fire!
He was using a cheap aftermarket chrome air cleaner!
Lots of damage !
You don't want this on a boat!

Re" Marine Flame Arrestors~
The older flame arrestors had brass or stainless steel stacked plates with air spaces in between.
The more modern units have a screen of a specific mesh size and thickness.
They work by quickly cooling the flame & disipating it's heat below the burnng & ignition temp. point that will support a flame.
The specific thickness and mesh size will also not allow flame to escape!
These Coast Guard Approved flame arrestors have very specific design specs.
Do not use just a standard car element & your keep flame arrestor clean & free from any oil that may come from rocker cover breather tubes.

[Dr. David Fleming]

That was a great answer. Wonder if you can cite your source?

[HOWARD O]

That was a great answer. Wonder if you can cite your source?

He might've gotten that somewhere, but silverghost has proven to really know his stuff! :yes:

[silverghost]

Flame Arrestor design
How do I know this stuff?
I have been around inboard boats all my life!
Bendix Corp. actually came up with the first true marine Carb. flame arrestor in the 1920s !
There is a US Pat. for it if you would like to search.
In order to propegate any fire you need an ignition sorce, oxygen, and a specific kindling temp. The flame arrestor stacked plates or mesh wire screen acts like a heat sink to rapidly cool the backfire-flame to the point where there is not enough heat to sustain a burning flame!
The flame arrestor must be able to keep at least enough protection if one cylinder intake valve remains stuck-open!
In the early days of gasoline inboard powerplants many boat builders simply converted any auto or truck engine for marine boat use.
Boats were burning to the waterline ! There were so many fires in boats in those days that the Coast Guard finally came up with a specification for a gasoline engine carb. flame arrestor.
Special drip pans were also required for any updraft carb. setups.
Sealed Starters, generators, distributers, and ignition protected bilge pumps were also required.
Bendix built the very first Coast Guard Approved units!
At the very same time CG Approved Fire Extinguishers first became required as did engine bilge natural passive ventilation.
In the late 60s bilge blowers were added to the CG vent rules!
These Coast Guard Rules remain to this day!

[HOWARD O]

I've got to ask......was your friend's burned '60 'vette the same as the one you own now? Something like, "Hey Joe, this car ain't worth squat now with that hood, I'll take it off your hands for a grand cash"???? :hyper:

[silverghost]

Not to to sidetrack this thread~
But the 60 Vette I have & owned since 1976 !
One day a long long time ago a friend brought me a car trunkload of old wheelcovers his dad had cleaned out of the family garage. "Keep what you want & throw the others away!"
I spotted 4 Vette Solid Axel Stainless Steel wheelcovers with spinners.
Just joking I said "Now find me the vette that go along with these !"
His reply "It still exists~ Want to go look at it ?"
He then went on to tell me that his brother's friend Kenny had the 60 Corvette and had intended to turn it into a drag race car.
Jump ahead we went to see the FI 60 high option Corvette but Kenny would not sell. It was partially apart.
Over the next four years I checked-in with Kenny but he still didn't want to sell.
One cold January day the phone rang; it was Kenny the Vette guy! Kenny had placed his mother into a nursing home and the house was sold ! The Vette had to go by the end of the week!
It was still partially apart and sitting on four flat tires on the rims.
"Was I still Interested?"
With six inches of snow on the ground the night before I went over to NJ with a borrowed flatbed and a friend.
We shoveled the driveway & jacked-up each wheel & hand pumped-up the tires & pushed the vette around 180* in the two car garage and winched it up on the flatbed with a come-along ; all the time the rotten tires were loosing air fast !
When I frst saw this 60 Corvette the complete Rochester Mechanical Fuel Injection system ws still on the old Chevy 283 .
When I went to pick-up the vette the entire FI set-up was gone.
Kenny had sold the entire FI system with the special FI aircleaner & gearbox FI drve distributor for get this~
$150. !!!
That special FI air cleaner alone was worth $700. in 1976 !
That's how I got my 1960 Vette !

The one that was badly burned by an engine backfire a few years back was a low power three-speed.
It is still sitting unused in the owner's garage~
The fire damage has yet to be repaired !
She has lost interest in the car but won't sell~
At least not YET !

Sorry about the thread sidetrack~ But Howard did ask! : )

[Top-Gun]

That is how I understood a flame arrestor to function as well, what threw me off is looking at the pictures of the K&N assemblies and not seeing anything different from their car offerings.

I decided to email K&N and specifically ask what the difference is between a 14x3" car air cleaner assembly and a 14x3" marine flame arrestor assembly. Believe it or not, they state the only difference is the lid and the base. For the marine units the lid and base are stainless steel, and a coast guard approved certification is stamped into the lid. The filter element is just a plain old K&N cotton gauze unit.

So by the sounds of it, theres nothing special about K&N's marine offerings, you can use any lid/base with their regular car filters as long as you don't need that coast guard stamp. I guess maybe the oiled gauze media K&N uses isn't flammable and since its encapsulated in stainless mesh they can get away with calling it a flame arrestor as well.

[HOWARD O]

Thanks Brad, that was a GREAT story! I can picture you in the snow getting that thing loaded! Maybe you'll have 2 '60 vettes before too long!



Sorry --- :hijack:

[Top-Gun]

Its ok, I'm a car nut too.

[silverghost]

I don't know about anyone else here~
But I, for one, am very suspect of many of the claims that K&N makes for their fancy air filter products !
Especially their claimed horsepower increases ~
I do not believe that their re-usable filter units are in any way true marine flame arrestors !
They are not built to absorb heat like a true flame arrestor ~
And what do you think happens to that oil that you put on the element?
Does oil not burn ?
Will K&N buy you a new boat if you have a backfire fire ?
We should set-up some sort of true world scientific controlled test for these K&N units !
PCB type oils do not support flame ~
BUT PCB oils are no longer legal !
Will K&N oil burn ?
We need to test it, along with their "Marine Flame Arrestor" filters !

[Rootsy]

In order to be used on a marine engine; a flame arrestor must bear a USCG J number certification. Therefore using anything not USCG Certified is against the law. Regardless of how well it'll work for the intended purpose.