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Thread: Carburetor/Annular vs. Downleg Boosters

  1. #1
    I am just trying to do some research on the difference between downleg and annular boosters on Holley 4150 carburetors I plan on doing some racing at the track and spend some time on the river as well what do you guys run out there on your boats and anybody that races out there have you tried both style carburetors and what difference have you noticed.
    I appreciate all your info the Scoob

  2. #2
    Senior Member
    Join Date
    Feb 2009
    I have a down leg but read somewhere that an annular works better on T?R set-ups.

  3. #3
    Does anybody else have any imput??

  4. #4
    Annular boosters require less signal to pull the fuel. I read a few articles in Hot Rod and Car Craft about booster design recently. In a nutshell, annulars work better on engines with big carbs at a larger rpm range because it at lower rpms, they still flow fuel where the downleg boosters would require a higher signal. This gives the annular an advantage because it allows you to run a larger carb for more top end performance without sacrificing low end performance. You can see where this would be an advantage on a street car. They test car they were using i think was a street engine running a dominator carb and they were trying to prove that a dominator could be run on the street. I can see where this would be similar on a jet boat.

  5. #5
    i went around with holley on which is best their techs dont no squat but thats another story. biggs performance can answer your ??'s or at least they helped me out do a search and you'll find them.

  6. #6
    Senior Member
    Join Date
    Feb 2009
    Scoob , I know you want to really run your boat hard and possible race from the last time we chatted so get the annular booster carb .Dont ask me why cuz I dont know.

  7. #7
    I was reading that you lose a little top end using annular boosters is that true

  8. #8
    Duane HTP
    Not in a jet boat.

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