Getting fresh air into engine compartment.
 

When I crack open my sunpad/engine hatch, Im picking up 1-1.5mph. Not really inclined to cut holes in sides of boat. Thinking of a couple bilge blowers working in reverse to bring in air. Maybe duct it nice right to the intake? Any ideas ?

You have to see if the boat is either starving for air or if you need to let the warm air out,as that will have a detrimental effect on your performance as well.

Be carefull with opening the engine hatch. I was out on lake MI. this last saturday running 70 mph and it was a pretty smoth ride untill I hit a mess of boat wakes. With the new drives the boat goes up and flies flat. The hatch came up and the wind caught it and tried to rip it off the boat. Now I have to repair the spot where the lift used to connect to the hatch. I plan on buying the newer style air intakes that are on the new SCARABS. And yes I also gained about the same.

Over on the Baja Board a while back, OTIS311 said he saw something like 3mph by cracking the hatch on his 29 Outlaw while at WOT. I have not yet had the ball$ to try it for fear of the wind ripping it off.

Well the wind only blows in the low to mid 50's at best for us :(

I have two vents on the transom above the swim platform. They have wave boxes (best description) on the inside to keep following seas out. Maybe ill just reverse wires on my existing blower on duct tape the hose up near the flame arrestor. If that helps then I know which way to go. Hmmmm...maybe a power inverter and a leaf blower :D

Leaf Blower seems to be a good idea. But must be mounted on the outside for a special hp look.

Well you could say that your boat has a blower then...:D

Same results, same question. I get an immediate 100 rpm and about 1 mph. Need to figure out how to pipe in some fresh air. As mentioned, keep in mind you will need an exit as well to achieve air flow. Maybe one in the front of the bay, one on the opposite side in back for exit, give a nice cross flow....in theory of course.

Sounds like you guys need leashes on all of those cracked open engine hatches...just in case....I'm thinking that the speed gains are not from more air, but from cooler air near the carb\air intake. Cooler air is more dense, mixes with more gas = more power. OK, so i guess it is more air. Putting a reversed bilge blower in a properly ducted vent would probably just slow down the flow of fresh air. But what do i know.....ive been sitting at my desk at work for 11 hours......

McGary

Getting cooler air to the carb is all Im talking about. There just isnt any circulation back there. When you think of the horspower it takes to gain 2 mph, or the cost of labbing a prop for a similar gain, there has to be a way to do this. Intercooled non-blower motor?

Ya got me thinkin'
 

I also run with the hatch open whenever possible and I do see some gains, but the problem is when I have passengers they are scared by the scream from the Whipplecharger. So I got to thinkin' why not rig up some kind of Ram-Air setup like on a car.
Add another two air intakes- one on either side and then fashion some type of collector around the flame arrestor that is directly fed outside air that is rammed in relation to boat speed.

Might take some engineering but I am sure I can rig something up. Time to start drawing some sketches!!!!!!

Dave

Same results for me also. Don't like running with the hatch open as the thing is 3/4" thick glass (big time heavy) and the ram is on the side.

I found something I want to try, but the problem is venting into the engine bay. I'd like to try NACA ducts. Anybody know where to get premolded ducts?

BTW, Velocity runs this kind of setup as standard equipment. Check out thier web site for details.

http://www.ramairbox.com/

Scott

Allan4 the exit route IS THE THRU HULL EXHAUST:D hows that for a force air outlet. :p

what about some nice fabricated brackets that are screwed/hinged on the inside of the hatch or better yet, the back of the bench seat. lift the hatch 3" or so and swing these brackets into place for a firm support of the hatch. Jay13 or someone even talked about a long extrusion with lighting holes along the whole length of the leading edge of the hatch. He even mentioned laser cutting the boat logo or name or someting into it. could look real cool???

Not practical for my application, but a friend with an HTM mounted 3 subwoofers below the bench seat in the fiberglass. The thing is, only one of them has a speaker in it and the other two are just 12" vents into engine compartment.

That was another thought I had. Running two 4" peices of PVC through under the rear bench seats letting air from the cockpit into the engine bay. I thought of mounting a bilge blower on the engine bay side of each one wired to run oonly with the motor running. The fans in the blowers would help deflect engine noise from coming through as well. Might serve as fire extinguisher access in case of a fire as well. I will figure somthing out on this.

Right now Im making home made prop holders that came out pretty nice for a few dollars each. Ill post pics in another thread later.

Ive been shopping. Bought two bilge blowers, some 4" flex tubing, and brackets. First going to just route the tubing into one of the rear vent boxes. I was really suprized how much air the blowers move. I just tested one on a battery at the boat store before I bought em. I think this will work well. I just want to get it plumbed so it looks nice as well. Do you think I should have them running whenever the engine is on, or hook them to the blower switch so two are bringing air in while one is taking it out?

Even with these holes, if there is not a free flowing source of fresh air coming underneath the seat, I'm not sure what this would do.... :confused:

I-1, I think your idea is pretty cool, but I still believe some sort of ram air would work best. I actually run with the blower on becasue I get some smoke and oil splashing out of the breathers when I run hard. I figure I can atleast draw in some fresh air via blowing out the old air. Not sure how much it helps, but it can't hurt.....besides burning up a blower motor....that's what fuses are for!!

The obvious is to put on a scoop, but I'm not going to tear up a nice padded sun deck for a 525hp motor in a 24 foot non-race boat. I looked into some Eddie air scoops for the sides to grab the air. but I would need to modify some of the engine bay. Let us know how your idea works I-1. Later

Rambunctious.....:D :D

A true ram air system doesnt see any positive pressure until 60mph or so. Not much effect until triplle digits. I know this as I have done testing with ram air systems on motorcycles. I still cant believe there is not a cold air induction kit thats coast guard approved available. Well...off to the bilge...

Plain and simple you need 2 scoops for air either out of the jegs catalogue or somewhere, Hillborne style type
drill with a hole saw and mount them to the sides of your boat by where the existing vents and blower lines are
so when your running, the scoops are catching the air and it goes into the bottom of the soop which is mounted on side of your boat up high, problem solves, air floods into engine compartment.
sonics, fountains ect all have scoops on the side for just this reason

Or you can make a vent between the hatch and the back seat and instead of your hatch going all the way down, you have it sit on this vent that goes all the way across the back and has screen ect in it
tons of ideas
with a screw jack, i cant see the hatch wanting to rip off
Or call jegs and order the fiberglass snorkel scoop like alot of the boats are using this day and age
tons of ways to get air in there
Jason