SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: Trukinbear on June 23, 2013, 04:47:42 PM
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Hi Guys, I've got a Nicson scoop like the one in this posting:
http://www.socaljetboats.com/wtb/nicson-cast-aluminum-single-4-barrel-scoop-wanted/msg178360/#msg178360 (http://www.socaljetboats.com/wtb/nicson-cast-aluminum-single-4-barrel-scoop-wanted/msg178360/#msg178360)
and I have a question.
After viewing some of the videos on this site I see a couple of boats with this vintage Nicson scoop, but they have it with the opening to the rear, not pointed into the airflow. Is this one of those counter-intuitive things where it works opposite of how you'd think?
Air intake points a) forwards, or b) rearwards?
My boat was a box of parts when I started for forgive me if this seems to be a stupid question.
Thanks,
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It's a matter of sound, when its forward all you'll hear is it sucking air and its loud. Spin it around and she's quiet.
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Hmmm, it appears to me that the abbreviated wing silhouette it displays when the air intake is pointed rearward would cause a massive low pressure (read partial vacuum) area right about where she'd suck air - turned the other way into the wind and it would be a high pressure zone which would aid in the engine's aspiration somewhat - or so it appears.
Ok, I'll buy the sound thing but I think it's quiet at the expense of power. I just didn't want to show up somewhere as a newbie and have everyone laughing behind my back that I'm too dumb to put the air intake/flame arrestor on properly.
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Without getting into atmospheric pressure, coanda effect, and other such scientific things associated with the large air pumps we use I'll throw in my .02 cents. Point it whichever way you want, you'll feel no difference in power. Nor is there and actual difference in power output. You don't drive fast enough to create a high enough pressure zone to boost power. And there is no air pressure drop with it on backwards to reduce power. Some guys turn it backward to reduce the chance of something flying into the intake i.e. hats, sunglasses, beer, water, hair etc....
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Built my hatch with the opening/scoop facing back.
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Hey I go plenty fast!!! Down river with .2 gallon of fuel and 105lb driver the boat hits 69 mph. ;) and the bigger the scoop the bigger the lies of mph
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Music to my ears in either direction!
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I have mine backwards 1.) Bugs, water etc. Wont fly in.. 2.) More quiet. 3.) Looks more propper/aerodynamic 4.) Motors creat air suction themselves. Like a big vacuum... either way it doesn't matter. If you like it forward then run it farward O0
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when i had my dooley scoop forward is was fvcking LOUD!
i dunno if that thing is a uscg flame arrestor but the popo's want scoops pointed backwards so if you backfire it doesnt melt the people in the back seat...
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Backfire in the 80's w aqua-net
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Just anecdotal evidence I know but I just stuck it out the car window to see what it does at 45mph - forwards it blows a powerful jet of air into my car, backwards it immediately sucked all the smoke out, and then some. It has a USCG approved flame arresting insert. Backfires? What do they thing these are jalopies? Back seat? Never had one. :-) But thanks for reminding me that away from the Klamath I need to watch my p's and q's.... no enforcement on the Klamath (Yurok Reservation) so we get lax, most aren't even registered much less have safety equipment and the like.
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While I'm not the argue with the lawman type (usually) re-reading 46 CFR 25/58 and see noting in that provision that would allow them to dictate the direction of your air intake. Even a velocity stack is acceptable... Maybe you are subject to some local regulations I'm unaware of, otherwise my boat has to meet the standards of the year of it's manufacture (1973). Lots of additional stuff was added 1980ish that I don't have to worry about.
I haven't ventured with my boat beyond the Klamath river, Crescent City harbor, and Humboldt bay - never been even asked for my paperwork. But, I'd like to venture out this summer and I guess I need a crash course on local regulations. You can get away with whatever you want on the Klamath, except take salmon out of season - that they'll get you for. :-)
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1. Its a jet boat- performance aint gonna be great.
2. It's a big block, it will draw air for intake.
3. Put some gangster rap on the radio and point it sideways at a 90*
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1. Its a jet boat- performance aint gonna be great.
2. It's a big block, it will draw air for intake.
3. Put some gangster rap on the radio and point it sideways at a 90*
Um, Ok?... NO!
1) Jet boat is the only way to get where I'm going.
2) She's got a small block, and yes it draws air for the intake and needs all the help it can get!
3) Gangster rap? Radio? I've got marine VHF, and CB - I'm so far out that there are NO radio stations.