Honda's words are a vindication ...
I have written for years of this (heat dilution disproportionately reducing energy dumped to coolant etc) ... but ....
we don't really know how much dilution (how lean) F1 is running (because we don't know what boost is used) ....
it doesn't seem hugely lean
From Pat Symond’s presentation:
* Thermal Efficiency of 52%
* BSFC 167gms/kw-hr (0.27lbs/hp-hr), occurs at peak power
* 800bhp from 1.6L (then another ~200hp or so from the hybrid unit)
* Lambda 1.3-1.4.
* Rules limited 18:1 geometric compression ratio. All are at max
* Spark assisted HCCI, which Honda pretty much showed (earlier in the thread)
* They are Miller Cycle engines, with IVC before BDC
* Separate oil circuit for piston oil jets that runs cooler than the other circuits
* Miller Cycle requires very aggressive intake valve opening / closing designs and a lot of boost
* Valve angles low (5-7*), obviously done for squish geometry
* "Omega" piston bowls. Illustration in video helps visualize that
* Modeling from the FIA shows around 5.5bar boost (~80psi or so) and 50% mass fraction burn by 8* ATDC. Lose 1-2% of MFB in the prechamber. Quick combustion from 2-80% MFB and a slowing combustion beyond that. This final 20% with slowing combustion speed is where knock can occur.
Honda’s tech review on 2021:
https://www-jsae-or-jp.translate.goog/e ... r_pto=wapp
Including a compressor map:
Compare that to the fuel flow limited DI / spark plug Audi DTM engine which runs at Lambda 1.15-1.38.
https://www.highpowermedia.com/Product/ ... -issue-136