Performance enhancement of divided exhaust boost (DEB) engine

A method for controlling a divided exhaust boost (DEB) engine, wherein the DEB engine comprises:

• a plurality of cylinders, each cylinder being configured to form a containment boundary that contains a corresponding combustion reaction of a plurality of combustion reactions;
• a turbocharger comprising a first scroll and a second scroll, wherein the turbocharger is configured to be actuated by exhaust gases produced by the plurality of combustion reactions;
• a first exhaust passage through which a first group of the plurality of the cylinders sends a first exhaust stream generated by the first group to the first scroll;
• a second exhaust passage through which a second group of the plurality of the cylinders send a second exhaust stream generated by the second group to the second scroll;
• a catalyst configured to receive the first exhaust stream and the second exhaust stream directly from the turbocharger;
• a third exhaust passage through which all of the plurality of cylinders send a third exhaust stream to the catalyst;
• and
• a scavenge valve disposed in the third exhaust passage and configured to control a flow rate of the third exhaust stream,
• wherein the method comprises:
• controlling the plurality of combustion reactions using the plurality of cylinders;
• controlling a flow rate of the third exhaust stream that is fed into the catalyst, by controlling an aperture of the scavenge valve, based on an operation load of the turbocharger;
• and
• controlling a flow rate of a remaining exhaust stream comprising the first exhaust stream and the second exhaust stream sent to the turbocharger, by controlling the flow rate of the third exhaust stream fed into the catalyst.