I have another post here inquiring about math for a venturi, and well, there is no perfect answer.
this is made from remnants of a fuel injected version of the same model of subaru I am running. The hot MAF is removed.
the fuel injected version had quite an atomospheric rumbling bellow, and I did not forget. As this opening is nearly 3 inches, and the end of the pipe is 2.5 (the same size as the top of the carb opening) I REALLY emphasized holding it in tightly. It should be much quiter on 3 degree cams (no back wards air to bellow) and it has a larger opening than the maf that was in it.
the inside metal is softer than the outside clips you see, acting as a gasket on the ring of the tube, and above it is to be siliconed. It is very rigid. I swung it around and banged things.
As the venturi goes, it is simply 3 inch to 2.5 inch and it is a long run. I used the whole thing to reach the carb.
Next photos will show it in the car. I am awaiting a high grade 90 degree silicone turbo elbow to make the turn from carb to the venturi. The flex part will also be in photo, and that is a subaru oem part. and of course there is the charcoal canister, and a place for the suck in side of pcv that I will add on the "level straightaway". photos will show results soon enough
any ideas on what will happen? This is not a fuel injected car, there is no heat riser. it is wide open venturi from the get go...with a modern air filter not even subaru can extinct.
the lower half of this is already bolted to the car, exact fit of course, no hacks. ourside source of air all ducted OEM exceot for what you see here, and will see when it is done.