what mike said


it always bothers me when guys start talking like wide lobe centers is high rpm, or for this motor only, or that motor,, the lobe sep is the distance between the lobes, doesnt tell you how much overlap you have,, or when you open and close the valves,,, which those are the parameteres that dictate where it all happens..

example,, im making this up as i type...


open/close @.050, duration, center

non-turbo/nat aspirated
int 32/68, 280, 108
exh 78/30, 288, 114
sep 111
overlap 62

turbo/nitrous
int 22/68, 270, 113
exh 78/20, 278, 119
sep 116
overlap 42

i didnt change the int close point just for reference though in a turbo you would,, but not in a nos application

int 22/64, 266, 111
exh 84/20, 284, 122
sep 116
overlap 42

i changed the closing point on the int cause you have boost to fill the cylinder better in the intake stroke so you dont have to leave the valve open aslong in the comp stroke, though it depends on rpm, cid, and port area. i changed the exh open point cause you have more volume in the cyl in compression due to boost so there is more cyl pressure which leads to quicker/more effecient combustion, therefore gases will ne burnt quicker so you can open the valve a lil earlier..

pro stock

int 28/72, 280, 112
exh 90/26, 296, 122
sep 117
overlap 54