Quote:
Originally Posted by stillsearching
....Why do normal 'variable displacement' systems have to deactivate the valve mechanically, why not just some kind of butterflies in the intake or something? (or/and the exhaust but I don't see how that would affect anything even left unblocked....
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Hi,
If you are going to deactivate cylinders, then simply pull the rockers from that cylinder, and make sure you do this both the intake and exhaust.
Why the exhaust too?
Because, anytime you start moving air around, there is a local loss of energy. With the exhaust valve opening, there is more airflow through the exhaust port and back again when the piston moves back down.
With both valves left in the closed position, air is repeatedly compressed, but at least there is no airflow, and compressing the cylinder results in some energy back into the system when that piston drops to BDC again.
Jim.