Ram Air / Air intake

[jeffswav]

Ok, this project turned much bigger than anticipated. So I started a new thread to keep the transom project separate. Here are a couple of pics so far, I will show the mistakes as well as the good parts.
First I cut out the opening bigger to get more air in. I first tried to use a 1808 biax in the opening to bring the air to a 4" opening. I wet out the entire piece but it was to heavy and would not hold in place. Next I used a peice of mat and attached it around the corners. However on the next step the mat fell apart and I had to start over. I made some cardboard templates to the shape of the vent/scoop I applied resin to one side and let it dry. I then appled 4 layers of mat and let it dry. The cardboard did not hold its shape and the vent will be trashed.
Ok, I have regrouped and the second attempt will be with 1208 on the inside. I will tack it around the edge first then wet out the inside after fully cured. I purchaced some floral foam and I am going to make a plug for the vent/scoop with that. The new glass will not be here till next week from uscomp.

 

[jeffswav]

Anyone have any ideas on what to use for a mold/plug, the vents have multiple curves. I had to heat up the floral foam to get it to the right shape. The foam is very porous so I used gel on the foam to make it smooth. It may or may not work, I am still working on them. Any ideas I am starting to get frustrated. The transom is all finished and ready for the engine to drop in. I would rather wait till I am finnished with all the glass work before putting everything back together.

 

[Trim'd Up]

Jeff go buy some rigid foam insulation from Home depot. It only comes in 2" thick sheets (or thinner) but you can laminate a few sheets together to get the needed thickness. It is a denser foam but still easy to shape with a rasp. You can get the sheets thicker than 2" at Carter Waters or Nuway but if your don't have a commercial account they will stick it to you. Your still going to need to fair it out with a filler of some kind to get it smooth.

 

[jeffswav]

Jeff go buy some rigid foam insulation from Home depot. It only comes in 2" thick sheets (or thinner) but you can laminate a few sheets together to get the needed thickness. It is a denser foam but still easy to shape with a rasp. You can get the sheets thicker than 2" at Carter Waters or Nuway but if your don't have a commercial account they will stick it to you. Your still going to need to fair it out with a filler of some kind to get it smooth.

I have been using the 1 1/2" x 12" x 36" foam. I cut it down the middle and I can get 2 molds out of 1 sheet. The vents I am trying to make are 6" x 36". I heat the foam up with the Ready heater and bend and form it to the correct shape. Problem is it tends to straiten itself back out a little. Also the tips keep breaking off because they are so thin. I think I would have the same problem with the other foam. It would take a while but I have thought about making the mold out of wood.

 

[jeffswav]

I just got the 1208 glass today, here is the latest progress. Almost finished with the inside part, still need to lay in a couple more pieces of 1208 glass. I also took a pic of the vent, still needs a lot of work, but it gives you a idea on were I am going with it.

 

[US1Fountain]

Will this be open, or is the shield of some sort that will go over it to keep water out?
Is there going to be 2 holes in each, intake and discharge?

Can you use a pvc pipe and lay glass over it to make a form, or does the profile vary as it goes from end to end?

 

[DAREDEVIL]

I hope u get all the air back out quick...........otherwise u will slow yourself down.

Ram air is really not the way to go on a boat. The engine just needs air to suck as much as IT CAN,,,not over pressure the engine compartment.:leaving:

 

[jeffswav]

Will this be open, or is the shield of some sort that will go over it to keep water out?
Is there going to be 2 holes in each, intake and discharge?

Can you use a pvc pipe and lay glass over it to make a form, or does the profile vary as it goes from end to end?

Ok, I have had the boat 11 years and never got any water in the vents so it will be open.
I already have a form for the 4" hole, if you look close you will see it.
Not sure what you mean by 2 holes, air goes in the vent though the duct, to the TB. It will not be completly finished till later in the year. I am just doing the fiberglass part now. For now it will just funnel into the engine compartment.
Just read your post over again, and I have 2 holes on the gunwall. I think that may be what you were asking.

 

[jeffswav]

I hope u get all the air back out quick...........otherwise u will slow yourself down.

Ram air is really not the way to go on a boat. The engine just needs air to suck as much as IT CAN,,,not over pressure the engine compartment.:leaving:

When it is finnished it will be piped directly into the TB. Why would it not work? Why suck hot air when you can force the cool air?

 

[insanity]

When it is finnished it will be piped directly into the TB. Why would it not work? Why suck hot air when you can force the cool air?

What happens when you get caught in the rain or catch a wave that sprays water directly into your TB?

 

[Knot 4 Me]

Are both sides going to be used to direct air into the TB? Do you have vents at the rear to relieve pressure in the engine compartment? Most side intakes that face forward are accompanied by some type of venting out back to maintain optimum air pressure in the engine compartment.

 

[jeffswav]

Are both sides going to be used to direct air into the TB? Do you have vents at the rear to relieve pressure in the engine compartment? Most side intakes that face forward are accompanied by some type of venting out back to maintain optimum air pressure in the engine compartment.

Yes, both sides. Yes, there are vents in the back on the gunwall.

 

[jeffswav]

What happens when you get caught in the rain or catch a wave that sprays water directly into your TB?

Never drive the boat in the rain. If I do I can disconnect it. Never had water splash up that high.
Well I guess never is not a good word, rairly may be better.

 

[Ted]

When it is finnished it will be piped directly into the TB. Why would it not work? Why suck hot air when you can force the cool air?

It will work, some of the Super V guys do/did it and saw noticeable gains with no other changes.

What happens when you get caught in the rain or catch a wave that sprays water directly into your TB?

You should build some type of Dorade box to prevent water from getting in. It should be easy. Basically take the hose from the vent and plumb it to the middle of a small box, something like 8X8 or so (bigger is better, whatever you can fit in unobtrusively, maybe a long skinny one under the gunwale). Put a small scoop facing down on the inside (look inside a wet/dry vac for reference). Now plumb a hose from the top of the box to the throttle body. Finally put a small drain or drain hose in the bottom of the box to dump the water that collects there, you can either dump to the bilge or overboard. You will lose a small amount of pressure this way but not take the chance of taking a gulp of water.

Never drive the boat in the rain. If I do I can disconnect it. Never had water splash up that high.

Never say never when it comes to boats.

 

[rchevelle71]

Never drive the boat in the rain. If I do I can disconnect it. Never had water splash up that high.

I never INTENTIONALLY drive my boat in the rain either

 

[J.T.]

Are both sides going to be used to direct air into the TB? Do you have vents at the rear to relieve pressure in the engine compartment? Most side intakes that face forward are accompanied by some type of venting out back to maintain optimum air pressure in the engine compartment.

+1

I did a something similar ( concept wise) to what you're
doing couple of years ago.

You'll want to have an exhaust venting ( at least for where the bilge
blower hose would exit) to "turn the air" ( that the engine doesnt consume)
in the engine compartment.

My project involved building an encosure that secured to the top
of the engine hatch that enclosed the flame arrestors, and was ducted
to the side vent area of the boat. ( so the engines would only draw
outside air.....nothing from the engine compartment)

I then added additional inlet ducting to turn the air in the engine
compartment.

Being that the boat spends a lot of time where any ram effect wont be
present ( idle, low speeds) and there isnt any engine vacuum to
draw air into the engine compartment, I added 2 bilge blowers
on the inlet side just to turn the engine compartment air.

I have them ran off of relays....whenever the ignition switch is on,
the blowers turn on.

 

[jeffswav]

Ok, thanks for all the input. This boat was designed for 330HP and I am running over 500HP now. The vents I had were way to small for the engine, the vents were poorly designed and needed some repairs anyway. The only thing I had not thought of was when I am trailoring it in the rain. I can always make some covers for the vents, to use for storage and trailoring. The boat is stored in a dry building so that part is really not a issue.
Anyone think this is a good idea? Cool fresh air seems to be better than hot air. What do boats with hatch scoops do?

 

[jeffswav]

+1

I did a something similar ( concept wise) to what you're
doing couple of years ago.

You'll want to have an exhaust venting ( at least for where the bilge
blower hose would exit) to "turn the air" ( that the engine doesnt consume)
in the engine compartment.

My project involved building an encosure that secured to the top
of the engine hatch that enclosed the flame arrestors, and was ducted
to the side vent area of the boat. ( so the engines would only draw
outside air.....nothing from the engine compartment)

I then added additional inlet ducting to turn the air in the engine
compartment.

Being that the boat spends a lot of time where any ram effect wont be
present ( idle, low speeds) and there isnt any engine vacuum to
draw air into the engine compartment, I added 2 bilge blowers
on the inlet side just to turn the engine compartment air.

I have them ran off of relays....whenever the ignition switch is on,
the blowers turn on.

Thats a good idea, I run the bilge blower all the time anyway. There is a 4" inlet and 4" outlet on the swim platform. I had not thought of running it with the key. If I do that then I cannot run it before I start the engine without the alarm going off.

 

[MOBILEMERCMAN]

It is really pretty simple. Air in air out. You want the engine compartment air temp to be the same as outside. The pressure factor is insignificant. IMO

An easy way to test is with a thermometer.

 

[jeffswav]

It will work, some of the Super V guys do/did it and saw noticeable gains with no other changes.



You should build some type of Dorade box to prevent water from getting in. It should be easy. Basically take the hose from the vent and plumb it to the middle of a small box, something like 8X8 or so (bigger is better, whatever you can fit in unobtrusively, maybe a long skinny one under the gunwale). Put a small scoop facing down on the inside (look inside a wet/dry vac for reference). Now plumb a hose from the top of the box to the throttle body. Finally put a small drain or drain hose in the bottom of the box to dump the water that collects there, you can either dump to the bilge or overboard. You will lose a small amount of pressure this way but not take the chance of taking a gulp of water.




Never say never when it comes to boats.

I have had this thread up for a while and I have really just gotten input on it today. I am already to far into it for a box setup. I have formed the inside part of the vent with smooth contours for the best airflow. I can alway disconnect the hoses if I get caught in the rain and have to run it. I am more conserned now about trailoring in the rain. I can always make some covers for the vents and that would solve that problem.