K&N oiled cotton air filter/flame arrestor

[Saline Marina]

So I am very new to boating but not to internal combustion engines. Amongst other jobs I was a development engineer on the GM 3800 engine project, passenger car application, but consider myself very lucky to learn about an ironhead pushrod motor in a dyno lab and in vehicles.

That said, I feel like its a transgression to run an engine without a filter as the dirt & grit is unavoidable and the increased wear effect is additive over time. So I was a little shocked to see boats basically running with a metal bug separator element (kidding, understand the need for the metal mesh) but no filtration.

I was led to the K&N site
http://www.knfilters.com/search/product.aspx?prod=59-3264

and I'm strongly considering this air filter/flame arrestor assembly which seems to cover both functions. Does anyone use this already and if so what are your experiences in cleaning and oiling the filter? Its in the neighborhood of $100 which seems like cheap insurance to me given the labor and expense of a new or replacement longblock.

Thanks for any feedback.

 

[undone]

Not a fan of K&N, but that's another subject. You won't find much dust or debris floating around on the lake, so filters aren't comment. You could put one on, but this may require adjusting the carb to get back to peak performance. EFI won't require it, but a carb will.

 

[jeffnick]

I bought a K&N but found it was more trouble than just replacing OEM.

 

[jerryjerry05]

No air cleaners on boats.
You won't need one unless you go off road.
You need a spark arrestor.
The Coast Guard can actually give you a ticket for not having one.

 

[Scott Danforth]

the only time you will find significant dust while boating is the middle east or the Suez canal. so the flame arrestor is all that is needed. also, if you think about it this way. Boat motors almost never wear out in their life time. they are usually murdered by improper maintenance

 

[Bondo]

the only time you will find significant dust while boating is the middle east or the Suez canal. so the flame arrestor is all that is needed. also, if you think about it this way. Boat motors almost never wear out in their life time. they are usually murdered by improper maintenance

Ayuh,.... Agreed,..... Flame arresters are a Must Have,.... air filters, Nope, No need,....

 

[500dollar744ti]

I always figured that if the factory put it there, it's probably okay to continue using it.

By the time an engine would wear out from dust, it will have long since been retired for other reasons.

The 3800 was a good motor, didn't like the later plastic intake design, saw a couple explode from leaky fuel pressure regulators.

 

[Saline Marina]

Dunno, when I look at the choke blades on the carb they are coated with some debris trapped by oily residue...which could be the way the PCV works on the 4.3. I still think its directionally correct even if its not the top priority for longevity as I haven't seen many smoking boat motors (from the exhaust typically that's one sign of low compression/burning oil or worn out valve seals). I would be surprised if any carb adjustments have to be made...the main venturis just supply fuel in relation to the volume of air passing by outside of other specialized jets. Actually TBI could be a problem as that's a simple speed density system, getting injector pulsewidth from a lookup table based on throttle position, rpm and the MAP sensor. That does not account for airflow differences. But I bet a TBI fueling calibration is a little on the rich side just for better power and reliable acceleration....and...no catalytic converter on a boat.....

I will probably put my $100 towards something else then but keep it in mind in case there's unexpected windfall

The 3800 was pretty much the most highly evolved iron head engine, lot of features developed for production, and then seen later in other pushrod engines like the balance shaft, cam-chain tensioner, the gerotor oil pump, roller pivot/roller tip rockers. Deep skirt block results in the very strong bottom end. The supercharger package was quite impressive imo, you see an evolution of the 3800 setup on current hipo V8s. The current small block V8 is probably the most highly evolved pushrod motor but the aluminum heads on the vehicle V8s aren't a very good match for marine apps.

 

[undone]

When you restrict the air flow before the ventury in the carb it reduces the pressure (creates more of a vacuum) at the jets and draws in more fuel. It's the same thing a choke does.

 

[undone]

EFI monitors the intake air flow and the exhaust and adjusts the fuel delivery to the amount of air being supplied.

 

[Saline Marina]

Correct, but only there is direct airflow sensing, like on SFI. (port fuel injection) One way is a hot-wire anemometer "mass airflow" sensor. In TBI there is no airflow sensing, the fuel flow is just found from a lookup table. With an oxygen sensor present there is a "fuel trim" which adjusts based on the balances of accumulated time the O2 signal toggles between rich and lean but its authority is very small as its more about trying to correct for very small vacuum leaks that happen because of the build variation in between engines. Not trying to start an argument but an air filter restriction is super small like 0.1" H2O water column and you'd never notice it except with instrumentation on a max power dyno run. Atmospheric pressure (the changing baro) is a larger factor than an air filter restriction (except clogged, nasty condition air filter).

 

[moosehead]

Saline, interesting topic and one I've thought about. I got over the particulate concern when looking at not only the marine environment (significantly less dust), but also the marine engine compartment configuration as compared to say an automobile setup. An automobile setup puts the intake and throttle body front and center in essentially a dirt windtunnel: particulates are funnelled directly into the intake. Vehicle manufacturers have come up with not only oiled and technically sophisticated dry filters to avoid this, but modern stock intake designs typically have several intake compartments and multiple elbow turns to help cut down on solids getting sucked into the TB.

 

[jerryjerry05]

More on this, IF??? your getting fine dust or stuff all over the motor or intake.
The belts might be too big or one of the pully's not aligned right?
Most time its more of a nuisance as once it's in the carb or throttle body it just goes on and gets burned.

 

[Bondo]

More on this, IF??? your getting fine dust or stuff all over the motor or intake.
The belts might be too big or one of the pully's not aligned right?
Most time its more of a nuisance as once it's in the carb or throttle body it just goes on and gets burned.

Ayuh,..... or Rusty pulleys,... especially for brine boaters,....