cam durations????

[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.

[rasp]

Lots of duration are primarily beneifical in high RPM motors, not lower RPM motors. Aren't the Stage 3s like 277 or something of duration?

[Drastic_Said]

stg3's are bc "272"s... but thats just advertised duration which doesnt really mean shit. its just a selling/marketing scheme IMO.


ACTUAL duration is where it is the actual duration of said cams. bc3's are 196*/184* duration +/- 2...which really arent all that too aggressive.


for the OP....if you run BC stg3s (or what you and your bud would like to call them, 272's) you will need springs...

[nutz]

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"