how much restriction are these?
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how much restriction are these?

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    senior member turbo wog's Avatar
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    Default how much restriction are these?

    how much restriction are these? this is one for a 850 cut to fit the 1150. anybody got info on how much h.p. on the dyno or mph, e.t ,anything on the restrictiveness? i think that the turbos can't pull through this good enough let alone being the draw through deal.
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    Much better with picture. As far as restriction? I was told once that a bare velocity stack will have a vacuum accross the opening after about 90 mph. As for the spark arrestor, I wonder there is a pressure drop on the back side at 110? Be safe, schick
    Last edited by schick; 12-08-2012 at 11:19 AM.
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    Senior Member bp298's Avatar
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    Quote Originally Posted by turbo wog View Post
    how much restriction are these?
    a lot.

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    i run a spark arrestor (k&n one) inside of my scoop, would that help rather than just out in the open? the scoop should create some type of pressure no?
    Last edited by ka0tyk; 12-07-2012 at 02:13 PM.

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    Or, how about 110mph wind going threw the SA and making a venturi across the top of the carb? Creating a low pressure just above it instead of in it. Maybe this is some of the fueling issues you are fighting at WFO? Be safe, schick
    Last edited by schick; 12-08-2012 at 11:20 AM.
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    Or Seth, either one Budweiser's Avatar
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    Wouldn't it be easy enough to do a comparison on the boat, noting changes in rpm and afr?

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    In the CP catolog theres a HP rating for the tall and the short ones. 600 , 400, somthing like that.

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    I run a similar spark arrestor since it's a convenient way to hold the scoop on. You can see it inside the scoop in the pics. Single 8896 Dominator on a Victor intake, been 110-115 MPH many times both at the track and the lake. On the squeeze, the motor's about 850 HP and about 775 HP on the motor. It's been on there for 3 seasons and as far as I can tell, no downside at all. Well, the Guy gives me lots of crap about my ski boat scoop but that's another story.

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    Quote Originally Posted by gn7 View Post
    ....... David 519 is 100% correct........

    Quote Originally Posted by fuelinmyveins82 View Post
    .....I think people forget that racing is supposed to fun. Losing shouldn't be discouraging it should motivate you work on your pile to make it faster.....

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    Quote Originally Posted by ka0tyk View Post
    i run a spark arrestor (k&n one) inside of my scoop, would that help rather than just out in the open? the scoop should create some type of pressure no?
    Quote Originally Posted by David 519 View Post
    I run a similar spark arrestor since it's a convenient way to hold the scoop on. You can see it inside the scoop in the pics. Single 8896 Dominator on a Victor intake, been 110-115 MPH many times both at the track and the lake. On the squeeze, the motor's about 850 HP and about 775 HP on the motor. It's been on there for 3 seasons and as far as I can tell, no downside at all. Well, the Guy gives me lots of crap about my ski boat scoop but that's another story.

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    I agree, having a scoop of some sort would help over just a spark-arrestor. I always wonder how much investigation is/was done when designing a scoop? How does the air flow into the carb at speed? Is the opening of the scoop the highest pressure, are the venturies closest to the front of the scoop seeing that pressure, and sending a different signal than the back? If your running 2 carbs is the the carb in the back seeing a different pressure signal? Or, is the air flow pressuring the the back of the scoop doing the same thing to the back venturi/carb, and the front carb running on a different pressure/signal?
    I would hope that the pressure in the scoop was equalized (everywhere), and all the venturies are seeing the same pressure inside the scoop.

    Be safe, schick
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    Senior Member steveo143's Avatar
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    I run a 10" x 4" arrester inside my Dooley scoop on a single Dominator on my PS boat. Get a bigger one Paul!
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    Or Seth, either one Budweiser's Avatar
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    Quote Originally Posted by schick View Post
    I agree, having a scoop of some sort would help over just a spark-arrestor. I always wonder how much investigation is/was done when designing a scoop? How does the air flow into the carb at speed? Is the opening of the scoop the highest pressure, are the venturies closest to the front of the scoop seeing that pressure, and sending a different signal than the back? If your running 2 carbs is the the carb in the back seeing a different pressure signal? Or, is the air flow pressuring the the back of the scoop doing the same thing to the back venturi/carb, and the front carb running on a different pressure/signal?
    I would hope that the pressure in the scoop was equalized (everywhere), and all the venturies are seeing the same pressure inside the scoop.

    Be safe, schick
    I always wondered too. So, out of curiosity, I did some internet research on Ram Air Effect last week.

    Pressure differential, much like a sound wave, travels the same speed as sound. So, all carbs and barrels will essentially see the same pressure within a scoop. However that doesn't rule out any inconsistencies caused by turbulence or other factors.

    For those curious, Ram Air Effect is measurable. However, it's very minute and measured in mb... Millibar... 0.001 of a bar/atmosphere/14.7psi. 70mb is about 1 psi. In the test articles I read, Ram Air Effect was able to produce 30mb (or 0.5psi) at 150mph.

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    I would not be as worried about the restriction as I would about the lack of actual "filtering". Everyone thinks being out on the water is clean air ONLY. Not so. There is still dust and debris that gets sucked into the motor - which is damaging. Under a hatch, there is still carpet debris and dust/dirt blowing around from crevices. Debris also gets into the engine area during travel to and from water. When I changed from factory screen to K&N, this is what I found. Boat had 140 hours at the time.



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    Quote Originally Posted by schick View Post
    I agree, having a scoop of some sort would help over just a spark-arrestor. I always wonder how much investigation is/was done when designing a scoop? How does the air flow into the carb at speed? Is the opening of the scoop the highest pressure, are the venturies closest to the front of the scoop seeing that pressure, and sending a different signal than the back? If your running 2 carbs is the the carb in the back seeing a different pressure signal? Or, is the air flow pressuring the the back of the scoop doing the same thing to the back venturi/carb, and the front carb running on a different pressure/signal?
    I would hope that the pressure in the scoop was equalized (everywhere), and all the venturies are seeing the same pressure inside the scoop.

    Be safe, schick
    Its way more complicated than can even begin to be discussed on here. Rest assured, the Dooley scoop is completely backwards in design to create any pressure in a carb at the speed a boat travels. And I run one, but backwards. Without the flame arrester, its enough slight determental to clean air flow into the carb and creates more turblence than pressure.
    Look at any NHRA Pro Stock scoop and you see a very different look than the Dooley.
    F1 is at the top of scoop design technology. Thousands are spent on F1 scoop designs. The NHRA guys simply follow in their footsteps. Bottom line, any scoop that has a larger opening in the fron than the internal space, or tapers front to back, is pretty much incapable of creating any significant pressure.
    Personally, I would never consider running a Dooley facing forward without a air cleaner or flame arrester to clean up the air flow into the carb.




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    Last edited by gn7; 12-08-2012 at 06:18 PM.

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    Quote Originally Posted by gn7 View Post
    Its way more complicated than can even begin to be discussed on here. Rest assured, the Dooley scoop is completely backwards in design to create any pressure in a carb at the speed a boat travels. And I run one, but backwards. Without the flame arrester, its enough slight determental to clean air flow into the carb and creates more turblence than pressure.
    Look at any NHRA Pro Stock scoop and you see a very different look than the Dooley.
    F1 is at the top of scoop design technology. Thousands are spent on F1 scoop designs. The NHRA guys simply follow in their footsteps. Bottom line, any scoop that has a larger opening in the fron than the internal space, or tapers front to back, is pretty much incapable of creating any significant pressure.
    Personally, I would never consider running a Dooley facing forward without a air cleaner or flame arrester to clean up the air flow into the carb.
    /

    Years ago I think I read something somewhere about "jet boat scoops". If i remember correctly, said scoop doesnt help performance whatsoever-and actually works better facing reverse?
    A vdrive buddy of mine with a blown BBC ran said scoop but had a couple 2" holes cut into the back side of the scoop. I asked him what for and his responce was: because it runs better. this was many years ago and his 90+mph Mandella smoked my sucky jet boat...

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