Given a cam of given duration at .050 can you calculate, from those #s, duration at .006 or .004. I'm throwing around some ideas for a custom grind cam. I have ideas for duration at .050 (226/232) , but need duration at .006 and/or .004(advertised duration) to calculate valve events and DCR. Also, can I calculate what the rpm range of a cam would be from it's duration at .050 and/or lift?(I'm thinking .570s in lift). Thanks!

 

You can't calculate duration @ .006 FROM a .050 duration figure, due to varriable ramp speeds. For example, you can have two camshafts, both with 240 deg. @ .050, and both @ .550 lift. But one of them can have a very aggressive ramp speed with a duration @ .006 of 280 ( a lobe intensity of 40 deg.) and the other cam could have a much softer ramp with duaration @ .006 of 300 ( a lobe intensity of 60 deg.). The cam that has the quicker ramp is going to make alot more power than the other. So in short, you must know both .006 dur. and .050 duration in order to determine lobe intensity, there is no universal ramp speed in witch you can take your .050 duration and compute .006 duration.

 

With duration @ .050 and lift, I can calculate ramp rate. Can't I calculate duration @ .006 using ramp rate somehow?

 

Well ya, but if you know the ramp rate, then you will, by default, know the duration @.006. Just add the ramp rate deg. to the .050 number, and that is your advertised duration.

 

Did not know that, now I do. Thanks chz, you're the man!