Author Topic: off the wall idea (Read 13192 times)

85drag250r · « **on:** January 29, 2014, 07:19:41 PM »

Looking for opinions on an idea I have about putting a "textured" type surface on the inside bell /throat of a carb.
Here is my reasoning behind the idea, if you have ever looked inside a rad valve, you may have noticed a slight textured surface.
I assume Boyesen did this to help atomize the air/fuel mixture going into the engine.

Is there a reason why this "textured" surface could not be applied to the inside of a carb to start the atomization a little sooner?

If the intake port on a cylinder is supposed to be left a little rough (for better atomization), then why do the carb manufacturer make the inside of all carbs so smooth?

fearlessfred · « **Reply #1 on:** January 29, 2014, 09:25:04 PM »

there should be no roughness until after fuel has entered the picture

85drag250r · « **Reply #2 on:** January 30, 2014, 04:36:15 AM »

sorry, i should have been more specific...lectron carb with the p/j at the begining of the carb bell.

Burns363R · « **Reply #3 on:** January 30, 2014, 09:25:16 AM »

You want laminar flow in the carburetor so that proper air/fuel metering happens. (if its to turbulent, you wont get consistant fuel flow from the main jet)
After the carb you want turbulent flow to atomize the charge.

rsss396 · « **Reply #4 on:** January 30, 2014, 09:42:48 AM »

the rad valve seams to be a sandblasted texture, probably done for a couple reason one to help fuel droplets atomize but also to probably give the product a nice looking finish after possible casting flaws are cleaned up.

There may be a advantage if it did create a boundary layer on the surface but I not sure much difference would be found.

jcs003 · « **Reply #5 on:** January 30, 2014, 10:12:08 AM »

the friction created from the turbulence of the air flow is the main precipitate of fuel atomization. the higher the velocity of the air the more tuburlant the air. the important part most people dont realize is you want a highly turbulant flow for the best fuel atomization.

john

85drag250r · « **Reply #6 on:** January 30, 2014, 12:34:30 PM »

Rsss, the "sandblast" type finish found inside the rad valve is the type of finish i want to use on the bell / throat of the carb.

John, i read a few articles on the effect of turbulence, and how important it is to an induction system. It got me to thinking, why not start the turbulence a little sooner with the carb.

Burns363R · « **Reply #7 on:** January 30, 2014, 03:16:30 PM »

Like i said you need smooth laminar flow over the jets to produce the right air fuel mixture. If you have turbulent flow over the jet, you will get random a/f mixtures. Id say this is all on a very small scale, but regardless is the truth.

You dont want to start turbulent flow until after the carburetor.

jcs003 · « **Reply #8 on:** January 30, 2014, 03:21:22 PM »

Quote from: Burns363R;24073

Like i said you need smooth laminar flow over the jets to produce the right air fuel mixture. If you have turbulent flow over the jet, you will get random a/f mixtures. Id say this is all on a very small scale, but regardless is the truth.

You dont want to start turbulent flow until after the carburetor.

again you come up with nonsense. you need to retake fluid mechanics. laminar flow is very slow (low velocity) its layered i.e. if anything there is a transitional flow through the intake and it accelerates through the venturi and get much more turbulent.

john

Burns363R · « **Reply #9 on:** January 30, 2014, 03:24:21 PM »

Laminar flow means even distribution, which also means even pressure distribution. Since the jets work on pressure differential, you will want laminar flow to create a consistent charge that represents the air being ingested by the motor. My fluids is correct sir.

http://blog.nialbarker.com/wp-content/uploads/2010/03/laminar_turbulent_flow.gif

Burns363R · « **Reply #10 on:** January 30, 2014, 03:25:38 PM »

You are referring to Reynolds number which incorporates many factors including surface roughness, velocity, diameter, mass if i remember correctly. Its all still related.

Burns363R · « **Reply #11 on:** January 30, 2014, 03:30:14 PM »

This article has some very good information in it. Its not directly about carburetors, but it does talk some about laminar/turbulent flow and effect on orifice plates. Basically our jets are an orifice plate.

http://www-personal.engin.umd.umich.edu/~ratts/me379fil/handouts/viscous/Meriam_Laminar_Flow_Element.pdf

jcs003 · « **Reply #12 on:** January 30, 2014, 03:35:11 PM »

Quote from: Burns363R;24076

Laminar flow means even distribution, which also means even pressure distribution. Since the jets work on pressure differential, you will want laminar flow to create a consistent charge that represents the air being ingested by the motor. My fluids is correct sir.

http://blog.nialbarker.com/wp-content/uploads/2010/03/laminar_turbulent_flow.gif

here is some elementary stuff for you to understand:

http://www.nationalcarburetors.com/carburetor.html

http://en.wikipedia.org/wiki/Laminar_flow

http://hyperphysics.phy-astr.gsu.edu/hbase/pfric.html

http://hyperphysics.phy-astr.gsu.edu/hbase/pturb.html

stop hanging around that idiot carla. you are starting to act like him.

john

Burns363R · « **Reply #13 on:** January 30, 2014, 03:36:01 PM »

Dude you do not need to be hostile towards me. Im just a regular guy. No need to be an asshole to me.

Burns363R · « **Reply #14 on:** January 30, 2014, 03:36:39 PM »

BTW your links support what im saying.