The piston moves from BDC to TDC; combustion products are removed through the open intake valves. The pressure in the cylinder decreases, exceeding the pressure in the exhaust manifold by 0.05-0.15 kgf / cm² at the end of the stroke.
To accelerate the release of gases from the cylinder at the exhaust stroke and the fastest decrease in the pressure of the gases acting on the piston when it moves from BDC to TDC, the exhaust valves open to BDC in the expansion stroke.
To improve the cleaning of the cylinder from exhaust gases, the exhaust valves are closed after TDC.
At the end of the exhaust stroke and at the beginning of the intake stroke, the intake and exhaust valves are simultaneously open. This period is called valve overlap. On the V-46 engine, the overlap is. 75 ° crankshaft rotation.
During this period, due to the presence of excess pressure. The combustion chamber is purged with air in the intake manifold. As a result of blowing, the cleaning of the cylinder from exhaust gases is improved and the valves, piston and nozzle atomizer body are cooled by air, which increases the reliability of these parts and increases the coefficient of filling the cylinders with air.
Forced filling of the cylinders with air, an increase in its density in the intake manifold due to pressurization, and an increase in the portion of injected fuel (cyclic feed) made it possible to significantly increase the power of the B-46 engine compared to the B-2 type engine (naturally aspirated).