Quote: Originally Posted by
rocko 
Ok quick question i was wondering how big of a cam duration can our heads take stock. Cause my friend has 272s in his evo 8 stock head just wondering if we can go that big or if the valve springs and retainers and valve stems. Any help would be great. Thanx.
for stock heads and turbo look more at the lift, you want more lift, if you have a big turbo with a larger a/r then duration/overlap comes into play "you need less back pressure to make duration a benefit or else it will just hurt performance"
stock heads and slight turbo upgrade stg1 cam
big turbo stock heads stg 2 cam 14's
ported head and big turbo crane 16's
i would say for ported race heads and large a/r turbines only should look past the bc stg2 or crane 16's
duration/overlap works by leting the intake push out the exaust charge "or vise versa" and you end up with a less contaminated charge "more air and fuel"
