Re: new australian intake manifold for the 4g63
I don't know. Things that often look like the way to do things or look better or smoother don't always end up making the most power. The same thing goes for head porting, lowering an intake port floor to do a gasket match, over porting with the bigger is better mentality, knife edging dividers, port matching the exhaust side, valve guide boss removal, etc can make a head produce less HP. I know AMS spent a long time dyno testing their intake manifold and wen't through many different versions before they settled on releasing that design.
Maybe if you think of the intake manifold plenum as a waiting area for ready to use pressurized air. A reservoir for air for the piston to suck in air when it wants it, not as something to direct the air right in from the turbo. You want the insides of the plenum to be somewhat rounded or have angled walls when needed to avoid 90 degree corners to not cause too much major disturbance when the air comes hurtling in past the throttle body to slow down and get ready to make the journey down a port with an open valve. Too big of a plenum and the turbo can't keep it full, too small and there isn't enough air ready to fill the motor at high rpms. You don't want air coming in a favoring one cylinder, maybe the raised ports cause a little turbulence to keep an air flowing along the walls from being directed right into a specific port constantly. Or it might allow the port to suck from a less turbulent area of the plenum away from the walls. Another possibility would depend on how air flows around the radiused inlet, one that sticks up into the plenum would have more of the radiused inlet which might give it more directions to be able to suck in air than just directly infront of the port.
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