Nothing exciting, just some planning.
I am considering a few different snorkel set-ups. I needed some figures to back up any decisions with regard to pressure drop, they are attached in the excel file.
This is the kind of information I wish was floating around on the interwebs so I'm posting it here.
My assumptions:
It's 25 degrees.
I'm driving at 80km/h.
Therefore, I'm assuming the "ram air effect" is a gauge pressure of 0.292kPa. This is calculated from a simplified Bernoulli's equation.
My revs are 4000rpm. That is where the power peak is in a TD27T, which I'm designing for, plus it's the redline. The swept volume is assumed to be 2.7L and the boost 7psi.
Thus, the flow rate through the snorkel is 0.15m^3/sec at the extreme.
The options are a standard A-pillar mounted snorkel with a cross sectional area equivalent to a 50mm nominal ID pipe, or a snorkel which passes through the bottom of the engine bay, along the bottom of the body, and runs up between the body and the tray on the passenger's side, with the throat pointing in the direction of travel just above the roofline, made from either 50mm or 75mm PE pipe.
For those too lazy to open the excel document, the pressure drop across the 50mm C-pillar snorkel is a huge 10kPa, for the standard A-pillar snorkel 6kPa and for the 75mm C-pillar, 1.8kPa.
I think those results stem from the effect of the incredible flow velocity on pipe friction. I'd say the TD27T unmodified can't suck that much air in reality.