I have had some luck with N/A cam combo's, but superchargers/blower cams is new to me. I guess a lot of lift is a given, but what about duration? Is a dual or split pattern better? I am building an all forged 383, AFR 195 heads, HSR and a procharger. ATI guys were telling me the combo could be up to 1000hp. They cant give an exact number till I give cam specs, type of heads/intake combo bla-bla. Anyway hoped I could get some ideas so I dont #@!* it up.

 

Intake duration doesn't need to be extended, but actually a little smaller by opening the intake a few degrees later in the cycle and closing a few degrees early.
The exhaust does need extended which is done by opening the exhaust a few degrees earlier in the cycle.

Basically this gives a strong exhaust bias split to the duration numbers, and reduces the overlap around TDC while increasing the LSA a bit.

If your best NA cam looks like this: 225/230 @.050 110* LSA
then a better cam for a blower might look like this: 220/235 @.050 115* LSA

Generally speaking, it will hurt you more to over-cam a centrifugal blower than it would to over-cam a roots type blower.

 

offering up something i just learned about a few weeks ago. i saw a guy in a procharged ls1 trans am running a blower grind cam (dont remember the exact specs) that had a short lobe seperation. instead of running the typical 114+LSA he actually ran a 112LSA in an attempt to clean the combustion chambers out at higher boost and rpm levels. dunno if it works well or not but just passing along something i saw. FWIW he made like 501rwhp with one of the flattest procharger dyno curves ive ever seen.

i also then learned that turbo honda owners do this sometimes as well. their blocks can safely rev to 10k rpms and some run NA grind cams on their turbo applications and dial some of the overlap out (read: not all) to achieve the same effect at higher rpms.