I found this page where the author posted formulas provided by K&N:
http://www.gnttype.org/techarea/turbo/airfilter.htmlI'm not sure how valid they are, but I did run those numbers on a spreadsheet for a variety of applications ranging from my LNF and S197 GT, to a 2014 GT500 and finally the SHO. Based on the cfm estimates for the K&N conical filters I'm using on the LNF and Mustang, they are slightly oversized for the airflow requirements. The stock GT500's conical filter is slightly undersized for the engine requirements.
But on the SHO, It looks like the stock panel filter is very undersized. The stock panel filter would be about 485 cfm (K&N listed test data for their panel filter to be 515 cfm) whereas the stock SHO with 10-11 psi of boost would need 648 cfm. With most of the tunes we are running, that airflow jumps up to 850 cfm. I think their forced induction formula is wrong as it needs to be absolute boost divided by 1 atm, otherwise if you run less than 14 psi of boost (relative) then your airflow requirement is lower than naturally aspirated - which doesn't make sense?
Looking at actual 1/4 mile ET and trap speeds, the available cold air intakes generally don't yield any noticeable improvements, maybe 0.1-0.2 seconds max. I've read about how some dyno'd their CAIs here and saw negligible gains in power. The stock panel filter was designed pretty much for the 2007 Ford Edge, CX-9, etc... which don't make a whole lot of power, and makes me wonder if there is room for improvement on the SHO. I understand there is more to the intake design than just the filter (plenum volume, pressure, etc)
Has anyone experienced noticeably better and quantifiable performance from a cold air intake or perhaps a better panel filter? I'm wondering if the stock air plumbing tract is more of a restriction. Even the catless downpipes and cat-back exhaust systems seemed to not reduce 1/4 ET a whole lot from what I have seen with 1/4 timeslips.
