Volumetric Efficiency

Integrated Cam × Head × Manifold Model

VE is computed from a physics-based model coupling three components:

1. Cam × Head Flow Integral

Integrates head CFM bench data over the cam event using piston-velocity weighting:

meanFlowCfm = Σ(Flow(lift(θ)) × |v_piston(θ)|) / Σ|v_piston(θ)|

2. VE Peak and RPM Band

vePeak = 0.85 × (meanFlowCfm / 82)^0.27
N_opt  = 247500 / IVC_ABDC × (1 + (duration − 240°) / 600)

3. Manifold Resonance (Helmholtz)

N_ram = 0.65 × (300000 / runner_mm^0.756)
      + 0.35 × (343×60 / (4 × L_eff × (1 + IVC_rad/π)))

VE scales modestly with MAP. Under boost, trapped air mass increases

proportionally with MAP_abs, captured via:

m_air = MAP_abs × VE × Vd / (R_air × T_IVC)