@lhu1281 has/had some on a thread I read a while back. You might have more luck searching for "velocity stacks". I'm pondering some for my Dells but they seem a bit expensive for what they are.
Will a vuvuzela work as well ? Seriously unless you have fitted a low ratio gearbox to a bus, will the engine ever rev high enough to need the airflow straightened... i thought these were for Beetles screaming around..
Classic Carbs have ‘em. https://classiccarbs.co.uk/products/dellorto-cars/dellorto-carburettor-trumpets
They increase the length of the induction tract and that helps maintain inlet velocity on single choke per cylinder carbs.
40mm dia x 50mm stacks on 40 IDF Webers. For 2316cc the carbs are too small but I hardly ever have the throttle wide open.
I didn’t buy them from Classic Carbs but that’s where I took the dimension from, I’ll measure them tomorrow if you really want to know what they are exactly.
I meant did you give any great thought to the height of the pipe, as they’re available in many lengths.
I’d like to say I calculated what the ideal length would be - but I just bought what was available that would fit in the existing air filters. I’ve just searched through my emails and I bought them from VWH, part number AC129199.