read something years ago that said something along the lines of
1) scoops, to reduce under hood temperature cold air in at the top helps blow hot air out of the upper end of the bay
2) scoops, to provide a ram effect at high speed direct over carb, sealed to carb
3) scoops to provide air into a large baffled plenum so the carb can draw centrally from a large volume of still -ish air
I presume
1) is ok for any set up
2) is good for all out high acceleration high speed where the flow into the scoop is so great the pressure is higher than atm pressure at the mouth of the carb
3) is the kinda thing you get on road race and rally cars and high end things like porches where the aim is to take advantage of a big still pool of air to promote a much less random consistent flow down the carb at all operating rpms
3 different ways to increase performance
i guess a combination of all, or any may work but large plenum of still air isn't going to be still air if you try to use Ram effects with it, so combining 2 and 3 may have benefit or it all may cancel out at a specific RPM, its going to depend on harmonics and stand-off
like HIFI speaker design there is way more involved than i have ever been bothered to find out
an air box with a cold air inlet certainly works at some RPMs. there are loads available for multi carb set-ups usually side draught and equally effective with FI.
But not as easily translated to a centrally mounted 4 barrel on a V8 due to lack of space
here is a sweary chap called Chris extolling the benefits of his air box on a I6
it kinda combines 2 and 3 BUT i think it probably makes most of its impact by truly isolating the carb intakes from the heat of the exhaust. notice use of a heat deflector under it as well.
There is a good 1 inch gap between box and heat deflector very good insulation and "shiny" doesn't emit or absorb heat well so that box is going to stay cool.
