fresh air induction

[reeveshd]

Hello:

I got an idea to run past you all.

94 glastron 17.5 foot
3.0l Lx mercrusier alpha one.

I just went and got my pvc tubing.

The plan is to bore two three inch holes on either side of of the word glastron on the plastic flip down cowling. Then with the holes and pvc pipe running a fresh air tube to the bottom of the spark arrester cap, not attached to the carb or anything like that.

Just with the two open ports and the two with the blower. I feel like the engine can and should breathe some cooler air. I am aware if the plan works the mixture may become lean, not too worried about that.

I just got the idea after cleaning the spark arrester the other day and the boat seemed happier. I just dont like the amount of heat the builds up in the cowling and do not think the engine should breathe that.

I am not really looking for performance increase or anything like that, I just want to make the engine happy.

Thoughts.....

Thanks

Reeves

 

[45Auto]

Re: fresh air induction

If it makes you happy, do it. It won't make enough difference either way to measure at your engine. That feeling you got that it made your engine happier when you cleaned the spark arrester was what is known as the "placebo effect". Unless your spark arrester was plugged almost solid, the only difference it made to your engine was that it "felt" happier to you.

Depending on the actual air flow and velocity at the point where you put the holes, they could easily be at a lower pressure than your engine compartment and pull air away from your carburetor. You saw the same thing on some of the old "cowl induction" hoods in the late 1960's where they cleverly put the intake in a low pressure area at the base of the windshield and DECREASED the performance of the engine.

Nothing wrong with doing it if that's what you want, just don't expect any difference in actual performance. Try taking the cowling all the way off, possibly it will be even happier like that!

 

[reeveshd]

Re: fresh air induction

I thought about taking the cowling down, but I dont have sea legs, I will fall in the damn thing.
The spark arrester was real bad, now I can see pokes of light coming through it now when I couldnt before. That was how dark it had gotten. Placebo maybe, but not completely.

The placement of the new ports with the front window open would draft pretty well I would think.

The low pressure area problem is interesting.

I agree it it is worth the experiment. if nothing else I can leave the ports and take the tubing out, then there should be no harm no foul


reeves

 

[reeveshd]

Re: fresh air induction

That idea was a bust, not enough clearance between the engine and the cowling.

However I did have a ram air port on top with vinal tubing that went to the bildge. I pulled it up and ran it to the spark arrester, while the blower still blows fresh air into the bilge, cheaper and easier to do, and if it is a failure then just un-do it and put it back where it came from.

Thanks or the advice

Reeves

 

[45Auto]

Re: fresh air induction

while the blower still blows fresh air into the bilge

Your blower should be blowing OUT of the bilge into the open air. It's purpose in life is to remove any gasoline fumes (gas fumes are heavier than air) that may have settled to the bottom of the bilge and are just waiting for a spark to blow up your boat.

You should have a hose from the bilge to the blower, then another hose from the blower to the vent on the side of your boat. The blower forces fume-laden air OUT of the bilge and fresh air is pulled in through the open vents.

Many boats have a vent hose leading from outside air into the bilge. This is so fresh air can be pulled in to replace the fumes that the blower exhausts to the outside. This link has some info on required venting systems:

http://www.boatus.org/onlinecourse/reviewpages/boatusf/project/info2b.htm

Ventilation systems must have two parts--an air inlet, and a separate air outlet. Both the inlet and the outlet must have ducts--which are tubes or hoses that extend down into the boat. Ducting for the exhaust must be located in the lower third of the hull--but above any bilge water.

Sounds like you may have just connected an inlet vent hose to your spark arrester. If your blower is working correctly and blowing OUT of the bilge, it will be pulling outside air through the hose to your spark arrester, thus pulling gas fumes from the carb through the spark arrester and into your bilge.

Be careful how you modify your vents, doesn't take much to set off an explosion if you have gas fumes in your bilge.

 

[reeveshd]

Re: fresh air induction

Well as advertised, there was nothing to report as success or failure. Had a good time with experimenting with the idea.

The blower is drawing fumes overboard. and the tube I used was never hooked to the blower in the first place.

Another idea my friend had. Has there been any one that tubo'ed a 3.0 Nothing with super boast, but just about two or three inches of boost.

I would be interested in that idea if anyone has done it. I just have not seen a great place to put a turbo.

Thanks

Reeves

 

[180shabah]

Re: fresh air induction

Has there been any one that tubo'ed a 3.0 Nothing with super boast, but just about two or three inches of boost.

Just search turbo

I'm am not even going to comment more than to say 3-4 people every year come on here talking about how it can be done and anybody who says otherwise is an idiot. So far, NONE have made it back to show how it WAS done.

 

[45Auto]

Re: fresh air induction

As 180shabah said, this topic comes up very frequently here. Apparently so far they've all decided it was cheaper just to go to a 4.3L, since none of them have ever posted back.

They used to make a turbo kit for the 3.0L. The company was M&W, and they went out of business about 20 years ago. The thread below has a pic and some discussion of a turboed 3.0L.

http://forums.iboats.com/showthread.php?t=359401&highlight=turbo