Engine Compartment Ventilation older 340's-380's

Raypanic · 07-09-2002, 04:28 PM

I have been thinking of adding some extra air flow to the engine compartment. My 1998 and similar 380's and 340's dont have the new side ducts. I found the tear drop shaped ones that are used on the eliminator daytona 30' seem to fit very colse on the bulge on the gunnel.

I think the would have to be made a little thinner as to flex arround the bulge. Most of it is flat but the bottom edge needs to bend about 1/4" or so near the rear. I would also have the "point" end made with a slightly larger diameter to fit the contours better.

If I have this done I am curious if any one else would be interested in the same? Posibbly drive the cost down some.

Also what do you think of the design and Idea in general?

MooseKnuckle · 07-09-2002, 09:25 PM

Ray,

Although I don't have my boat anymore, it seems like a bunch of work to do the job. When ever I wanted more air in Engine Compartment, I would just raise the hatch a little. Might be easier and less of a hassle. Just my 2 cents.

After all your hard work, you should be on the water and not working on additional modifications. Save those for the winter

Hope you season is turning out good now. I still might get a boat this summer, it is a Buyers Market for sure.

Mike

Raypanic · 07-09-2002, 10:43 PM

Hi Mike! All is going well this year, I decided to take the boat out over the 4th weekend to get some work done. Mainly issues with my wife - Too loud (mufflers) Potty dont work (Electric conversion). We were spending the weekend at my house watching fire works and stuff with the neighbors. I did remove and re-build the seawater pump. This is where the black gunk was comming from in the bilge, the front shaft seal was bad. I also put on drive temp indicators too. I should be back in the water on Friday or saturday.

I started thinking of scoops last fall but after seeing my Wife and kids use the sunpad I realized that would be a problem. I had to find out another solution. While I was running I did notice a reasonable amount of air pressure on the area where this bulge is. I figured It would be a good spot for a intake. Actually the installation should not take more than a couple hours and If I can get eddie marine to custom fabricate a couple of grills I think it would look good and be very functional.

Hope to see you out there soon, I was at Brennan Marine the other day and the have a nice 340 in stock....

Goomba II · 07-09-2002, 10:52 PM

Ray lookes like a clean set up, my old 29 Entiser had a vent in the same area but it was more square looken. The tear drop desighn you have lookes more stylish. Your rite ya definatly need more air back there.

Scott · 07-09-2002, 11:50 PM

Ray,
I have had a couple thoughts on the air issue. I need to crack my hatch and see if I have any speed changes (in the past it made no difference). Now I'm seeing that my flame arresters might be effecting air flow to the motors (check out the tech section) sooo if I change over to a different flame arrester will I not have enough air ?????????? (scratching my head). I have looked in the Rex Marine catalog and really liked the ones they make,some even have a built in cleat. They also offer them in many diff colors like purple

The area you show would not be my first choice if I do this I would move it back to the same area they install the new ones at. The shape and style should look good back there. I have also seen them add on the straight (camper style) vents

Yuck!
Any thoughts? throw them my way

Look for your props I sent them today! Thanks again I now owe you one

Raypanic · 07-10-2002, 08:34 AM

Scott, Wich Rex marine vent are you looking at? A while ago I looked at their catalog and didn't see any that caught my eye. Are you seeing it online or do you have a catalog? I requested a printed catalog but they said 30 days +.

I also intended to pipe a duct back to the compartment from behind the vent. Kind of a ram air effect.

Scott · 07-10-2002, 10:06 AM

Ray,
I'm out of town but looking at the online picture I'm thinking those are the same. I like the idea of piping it to the back. I would try the hatch raising trick first to see if it really needs it.

The story from PQ goes like this (or so I was told) that one of there X testers named Ryan used to crack the hatch on tests and would see a change of up to but no more than 1 mph. When Ryan (nice guy by the way) and I were testing my boat he tried it and got nothing but a lot of noise

he and I'm guessing others convinced the powers to be to change the mold to incorperate the vent. It might of helped the air flow???????? mabey the looks???
I would think that they would of used a airflow meter (easy to use) to confirm results before putting in a design change. Remember the wrong placement could actually cause less air to the desired location,venture (sp) type of effect. But my best guess would be that it's better to have it. One other thing to think about is water into the bilge or engine

So with all that said I'm ready to experiment by cracking the hatch again and looking for speed changes also I have a point and shoot thermometer that I can use to monitor temps.
One other thing they had told me was that a lot of air is pulled in through the side compartments and to keep them clear. Sorry no way on that one I store life-Jackets on one side and fenders and lines on the other. I rather cut in a vent than give up that space!
Sorry to ramble on just my morning wake up drinking coffee thoughts

Scott

Raypanic · 07-10-2002, 11:34 AM

FWIW, I hear that EFI Engines are effected more by hot air than carb engines this is one more reason for the extra ventilation. I think it has something to do with the chilling effect carbs have on the intake higher up in the stream. whereas MPI do not benifit from this because of the close proximity of the injector to the port.

07-10-2002, 08:48 PM

Ray do have have "relief vents" on each side of your stern? You can only get X CFM through your arrestors, anything more causes pressurization and most probably will slow you down. I think the PQ designers understand that. That would be for a stock application, yours my very well be different. I agree with the rest, crack your hatch an inch and see if you pick up any rpm's. Mine did zip! If you go ahead with the vents, billet or stainless is my 02.

I'm betting part of the new design is to allow heat to escape. After a run and shut-down you can feel the heat pouring up and out of those side vents. Never have had a vapor lock issue.

ps. your right aboout the efi motors and high temp/humidity. I can be down 2-4 mph when over 90/90.

07-10-2002, 09:00 PM

Only shot I can find right now