Knock Margin Table

End-Gas Temperature Model

T_crank = T_IVC × DCR^(γ−1) × S/V_correction

Note: DCR is used here, not ECR. Using ECR would imply physically impossible

compression ratios under boost and produce wildly inflated temperatures.

Knock Margin

Knock_margin [K] = (Tai_eff + SquishBonus) − T_crank

Where:

• Tai_eff = autoignition temperature, corrected for lambda
• SquishBonus = end-gas quench benefit from squish land geometry (0–30 K)
• Positive margin = safe; negative = knock occurs

S/V Heat Transfer Correction

High surface-to-volume chambers (bathtub, wedge) lose more heat to walls:

T_actual = T_adiabatic × (1 − SvFactor × (1 − 1/DCR^0.4))

This gives slightly more generous knock margin for high-squish chambers.