motor starved for air?

[jwbbuck]

I have only 2 vents feeding air to my engine compartment. Round holes about 3 inches in diameter. One of them is plugged with the blower vent hose so I'm really only breathing through one. I had a friend open the hatch and I made a WOT pass. Boat traffic screwed me up, but I think saw an extra 200RPM.
How many vent's / what size are you using?
530 horse, 502 Chevy, 5000rpm.

[OMEGA_BUBBLE_JET]

you made a WOT pass with a buddy holding your engine cover open:confused: :rolleyes: that doesn't sound very safe. If you picked up any rpm I would imagine it would be from cooler air not more of it. a 3" hole can flow more than enough air for you engine. With the hatch closed the heat from the engine heats up the air under the hatch making it less dense which means less power:frown:
so the answer to your question is no your engine is not starving for air.:)
Omega

[powerplay230]

Another possible factor depends on size of boat. I used to have a small Baja that picked up 3 or 4 mph if passenger sat in back instead of front. Boat was small fairly light outboard model, when I found out that I could break 70 that way I almost took the front seat out j/k..:p

[celeb1]

I had to make a new engine box, my old one was way too restrictive, I would pick up 2 MPH on the GPS with the cover open. I am not sure how much CFM a 3 inch hole will feed your engine but your intake manifold has a larger diameter than 3" for sure. Air flow (velocity) and direction is important and it sounds like you are deffinitely restricted.

[Tinkerer]

A single 3 inch hole is NOT enough.
I would try three 3 inch holes or more.
Get as much air in as you can without making the boat look bad or weaker structurally.
I have the same problem with my boat but havn't come up with a good solution yet.
raising the hatch works well - but mine has a motor lift.

[HP350SC]

On my old boat (20' v-hull) there were filler panels between the rear seat and side of the hull. I removed mine to allow more air in. You could replace them with netting so skis or whatever can't slide all the way back.

[powerplay230]

Good idea Mike or cut an extra pair of holes in them and cover with something like speaker covers or??? Would be a lot easier to cut in 1/2" plywoood that easily replaced instead of glass. Hmmmmm my shrink even likes that idea.
Rick
Mike still having goodluck with that SVT truck?

[powerplay230]

Good idea Mike or cut an extra pair of holes in them and cover with something like speaker covers or??? Would be a lot easier to cut in 1/2" plywoood that easily replaced instead of glass. Hmmmmm my shrink even likes that idea.
Rick
Mike still having goodluck with that SVT truck?

[HP350SC]

Yep, she's a runner.....;) I'm picking up my bed mounted fuel tank Thursday. It comes white, but I'm going to paint it sonic blue to match the truck. No more coming from the airport with 30 gal. avgas in cans.

[powerplay230]

Probably a silly question but have you done any work to the truck to improve its' yeah gas mileage thats it... If you are I have the email addy of someone great to talk to, guy in atlanta who was the webmaster/guinea pig for JLP performance, if I remember right his was well into low 11s or high 10s..
Rick

[Hotcrusader76]

Why don't you consider using a blowthrough carburetor hat? We use these on supercharger set-ups but it'll serve the purpose of a cold-air type supply as well. The inlet is 3.5" round.
http://www.tpcracing.com/product_images/auto-Blowthrough_650_225.jpg

[Sand Dawg]

I like the "hat" idea, and then just plum it where ever good air is available????