Filling Difference: 2V vs. 4V

Hello,

Here's a thought experiment: If I have two diesel engines with the same displacement, one with two valves and one with four valves, both with the same intake air pressure at the same intake air temperature, the same swirl level, and the same exhaust back pressure after the exhaust valve(s)... approximately how much less fresh air mass is actually present in the cylinder of the two-valve engine compared to the four-valve engine?

Hi,

It also depends on the speed. The higher the speed, the more pronounced the effect.
The required boost pressure for the 2.0 TDI-PD 16V 103kW engine is significantly lower at 4000 rpm compared to the 1.9 TDI-PD 8V 96kW engine.
Ohne Gewähr nach Gedächtnis: 2180mbar für 103kW beim 2.0 PD 16V und 2350mbar für 96kW beim 1.9 PD 8V. Beide without DPF.

I can gladly provide you with comparison values for the necessary "Russian-free" boost pressure for 103kW 2.0 TDIs, comparing 8V and 16V engines, but it will take me some effort.
Let me know if you need the exact values.

Best regards, Rainer.

"Thank you, that's a big help, especially since the 103kW 16V model is also Euro 4 compliant."

I agree with Rainer.
The cross-sectional area is definitely larger for the 4V.
Because the pressure loss increases with the square of the flow velocity according to Bernoulli's equation, the 4V configuration has an advantage, especially in the higher RPM range, which allows for greater power output at the same boost pressure.

I would rather let the engine developers handle that calculation right now.