Engine characteristic changes as a result of changeing Lobe Seperation Angle

We are thinking of going from a 116 LSA to a 114LSA and changing durrations from 296/296 to 288/290. The motor is Cnc block , veny head ,DMPE charger. What would be the expected engine characteristics from such changes? We want to get more bottom end grunt and pull the power range down .

 

Reducing your duration will generally 'move down' your effective power band. I ran the numbers real quick and it appears that you will be opening the intake valve at about the same point, but closing it earlier. You will also be opening the exhaust valve a little later, while closing it at about the same point. You will also be reducing your overlap by about 3*. The earlier intake closing point will 'trap' more charge into the cylinder (observable by a dynamic compression test), which theoretically increase your peak cylinder pressure. If you run high boost or really high compression, this may be an issue for you. Just remember that as you decrease your duration, the peak lift of your lobe becomes more critical because you have less time to get to peak lift so your acceleration rate goes up also. The reason that I mention this is that I have been 'caught' a few times with camshafts that are still making good power, but get into 'valve loft' or uncontrolled valve motion at elevated RPMs, Reguardless of how much spring pressure I would run. Are you looking to reduce the rpm range of the engine or are you planning a gear change? Just curious of why you would like to reduce the RPM range where the engine makes its power? Is this a clutch car?