Increasing air flow to carburetor

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brendonv

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Well, my 2 horse has a tube from the valve breather tube to the carburetor to maximize air flow. I was also thinking of drilling a little hole in the engine cover and sticking a tube from there to the carburetor so the air given off by the flywheel would also maximize are flow to the carby. Its like a free air generator and its not being used (other than cooling the engine of course). Victa engines have a tube going from the decompressor and flywheel area to the carburetor to maximize air flow so why shouldnt the briggs have it? It would be a piece of cake to do and might be a real good mod. Also if i were to do this,(ill do it anyway as what have i got to loose, its just a little test, if it doesnt work then so be it) where should i put the tube so i get the most air flow from the flywheel?

Thanks guys,
From Brendonv
 

mike75925

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i have also thought of this, i will be using the trial and error method. depending on the type of briggs, you could add a channeling system to guide the air where you want it. decreasing the size of ducting will increase pressure. happy hunting!
 

BAMBY

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if it were me, i would make it so that the only way (except breather) to get air into the carb would be the blower housing, that way NONE of the hopefully built up pressure can escape back out the carb opening. the "pressure" will stay in the carb and ducting...

your ideas sound promising... goodluck,
BAMBY

PS where to put the tube? i think you should have a pretty large duct on the blower side, that slowly tapers down to match the carb opening. my thought would be from the top of the blower housing, on the left side near the carb, a little higher than the height of the ignition coil. maybe you could put some way of ramping the air toward your duct too, like a piece of sheetmetal on the inside of the shroud curved to direct air at the duct. i still think the engine would get plenty of cooling.

in any event (i think) your gonna need more than just a little tube the size of the breather one. the breather one is really to reduce emissions by burning the crankcase gasses and not releasing them straight into the atmosphere. i dont think the breather tube is for maximizing air flow though.
 

THE HUNTER

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yeah, the tube from the valves to the carb has nothing to do with increasing power, its all about emissions (hydrocarbons specifically). and also to help keep dust from being sucked into the crankcase if the valve that maintains a partial vacuum in the crank case fails.
 

oscaryu1

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Done that before. Useless - by the time you get it through the filtration system, it's virtually nothing.

That is, unless you want to be blowing dust-filled air into the carburetor.... :)
 

mike75925

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seal the blower body to the engine case, the 'filter', that keeps grass and the like out, could use a oiled foam element on there. upgrade your fan to taller blades or redegree them to catch more air. some guys were speculating on using electric assemblies. the fly wheel is large enough to put a belt drive and your ratio would be like, idk, 10:1? problem would be to find a compressor unit with a long enough shaft to accomodate a pulley for drive. i have a couple turbo's off of motorcycles, but they are way too big but i may cannabalize the compressor wheels and make my own scroll, the pcv breathers aftermarket should be small enough for hairdryer/small squirrelcage setups
 

mike75925

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forgot they started making superchargers for r/c airplane engines like a bill per
 

mike75925

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i forgot i have a couple of edf64's. i read up and they put out 7.69ounces of thrust (weight 73 grams, or 2.5 oz). by tapering it's exhaust i can get a higher pressure. just hope my engine has the generator on it!
 
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