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Discussion Boards => Car Guys Discussion => Topic started by: XH29N0G on May 06, 2017, 05:46:19 PM

Title: Why aren't accelerator pump nozzles below the butterflies? (and other questions)
Post by: XH29N0G on May 06, 2017, 05:46:19 PM
The answer is probably obvious (like the gas would be sucked out of them, or they couldn't be changed), but I started wondering why they were not put closer to the manifold to make them more effective at getting gas in quickly. I figured someone here would know; so I posted a new thread.

I don't have any other questions yet.
Title: Re: Why aren't accelerator pump nozzles below the butterflies? (and other questions)
Post by: Ryan.C on May 06, 2017, 09:10:05 PM
If I understand your question correctly I think individual carburetors is part of your answer. The other part would be the gas dynamics of the intake that is to say a long intake runner typically increases engine torque. Carburetors are inherently inefficient. It is best to inject the fuel directly into the combustion chamber just before ignition.  If I am way off I would like to hear others chime in.
Title: Re: Why aren't accelerator pump nozzles below the butterflies? (and other questions)
Post by: ACUDANUT on May 07, 2017, 09:18:02 AM
You must be bored  :scratchchin:
Title: Re: Why aren't accelerator pump nozzles below the butterflies? (and other questions)
Post by: XH29N0G on May 07, 2017, 03:10:58 PM
bored   :smilielol:

I have plenty I am supposed to do.  I suspect it might be procrastination.
Title: Re: Why aren't accelerator pump nozzles below the butterflies? (and other questions)
Post by: JB400 on May 07, 2017, 08:35:35 PM
I think the reason why the nozzles are above the butterflies, is because of fuel atomization.
Title: Re: Why aren't accelerator pump nozzles below the butterflies? (and other questions)
Post by: daveco on May 07, 2017, 11:53:47 PM
Too much vacuum below the butterflies. Would just suck fuel through.
Title: Re: Why aren't accelerator pump nozzles below the butterflies? (and other questions)
Post by: XH29N0G on May 08, 2017, 06:08:12 AM
Those make sense.  Thanks. 
Title: Re: Why aren't accelerator pump nozzles below the butterflies? (and other questions)
Post by: John_Kunkel on May 08, 2017, 03:31:30 PM
Quote from: JB400 on May 07, 2017, 08:35:35 PM
I think the reason why the nozzles are above the butterflies, is because of fuel atomization.

:iagree: The nozzles above the butterflies inject the fuel into the center of the airstream where it's atomized, at part throttle below the butterflies the airstream wouldn't be centered on the throttle bore.
Title: Re: Why aren't accelerator pump nozzles below the butterflies? (and other questions)
Post by: resq302 on May 09, 2017, 08:32:40 PM
I agree.  Below I think it would get too much vacuum causing the fuel to get sucked in like the idle circuit.  Above where they are located allows for better fuel atomizing to happen and a better burn.