Engine room air intake

Do you have pictures? Mine is an 88, but I doubt they changed that much and I find the air flow pretty restricted. I'd love to know if we can easily increase it.

What's required is that boat buyers have an educated eye, and please do tear apart your boat for education. You want to be familiar with every inch of it. Better to do that at the dock than when you're broken down on the water (or worse, taking on water). As far as air intakes are concerned does your vent encourage air to be pushed in, but water to be blocked out and drained overboard.

Nothing is required as far as having an opening there. Usually they have a lip and a drain to keep water out and only let air in. Some have screens, most from your era do not. The engine vent is required to allow enough air in so that the motors get enough airflow at WOT.

Don’t mess with it and keep on with the woodwork it’s been doing a fine job for 35 years let it be.
If one side has some sort of factory installed plastic shroud and the other doesn’t try to make up your own the best you can and duplicate it but don’t worry about it too much in my opinion.

My 44 has a glass shroud on both pt and stbd. Ducts come off the top to prevent water from having direct access to the ER. You can continue to run her in calm conditions but IMO I would get it fixed to keep as much salt out of the ER as possible.

When you run at cruise speed, is it hard to open the engine room door? You can install a vaccuum gauge and see what vaccuum the engine room has when at cruise speed. But if the engine room door is being sucked shut, that is the first indication that your vents are too small.

Restricted air flow into the engine room is normally not the result of inaccurate design in popular boats that have been around awhile. Is there any general complaint about that from other owners? It's usually because something has been changed or unwittingly restricted. The engine room door is the usual first test at rpm for low air flow. Most vessels have other areas for ER air such as over the top of the cockpit liner or thru the bilge that draws fresh air from areas or vents in the living area. Some boats also use a built in snorkel. Most ER blowers move about 400 CFM and one may vent in, the other vent out (I have 4). Hard to imagine those making a big difference to air flow running at RPM, and an ER fan is only good for moving air around. It's good for dispersing hot air as it collects, but it will not add air to the ER. Crushed filters can often occur from undersized filters or allowing them to clog. Is the OPs complaint lack of air or wet air passing thru an unprotected side vent? Many vessels have a rectangular box covering the inside of the side vents with an open top like a flower box, or similar structure. This knocks down water droplets and lets them collect in the box and naturally drain Hard to completely "dry" the air coming in when you have side vents - the air naturally has a higher content of water by the natural throw of salt water from the hull at speed

So after you determine the ER door is difficult to open here is another test. Take the boat out , get everything up to temp and run up to your cruising rpm. Then have some one open a cockpit hatch or the ER door while you monitor your tachs. Did you gain any RPM? Are you exhausting less smoke?

It's only another test like looking for negative pressure on a door. Why would a 1984 boat that is fairly popular all of a sudden develop insufficient combustion aeration? I'm thinking that's not his problem, or something was modified that restricts that flow - maybe by a former owner? Is insufficient air a generic complaint on that model?

The unguarded air vent is a concern because the outboard side of that engine and every thing else located there is probably getting "splashed" to some degree while on plane. Also, if the hull rinses and washes are not done carefully that hose stream is going right into the engine room. Mike G. have you gone outboard on that side to look at your equipment?

It's a lot more common than you think with Sportfish. I've seen some hulls with molded in engine room vents origionally designed for 660 HP diesels when first introduced end up with 1100 HP diesels installed by the factory a few years later. A lot of times a SF will be built, even big ones, and the largest engine at the time might be 1600HP, but 3 years later same engine puts out 1900 hp or they're installing 2600 HP diesels. Well the origional air vents in the mold generally stay the same. So don't always expect that the builder got it right.

Agree with you. My focus was more on end user complaints. Has lack of air been a common complaint? This is a 1984 manufacture. Has the boat been repowered?

It could be that the air vents are borderline in a normal climate and the hotter Mexican air and the engines need more air as it's less dense. Perhaps cutting a hole under the gunnel and running a 4" blower into the engine room would help with airflow.

If air restriction is in fact a problem, he could also create a convenient opening to additional air somewhere outside the ER and lay in a 6" tube or tubes that simple allows the engines to draw the air thru? Staying away from any "station wagon" affected air source. The simple inertia of moving forward and using a scooping device would be good also.. I'm still not convinced he has an aeration problem, unless he had his motors upgraded to Capt J's point, or something was changed post production. Dunno....

Do you hear any whistling from an imperfect hatch or door seal? See any telltail dirt streaks indicating a sucking air source?

Did these boats come with fire suppression doors on the intakes? If so, it could be one dropped shut, or something along those lines. Odd that port and starboard are dissimilar.