Quote:
Originally Posted by christofoo
It's 10-20F here this week and my temp gauge barely gets going with a full grille block and a block heater over my 10 mile commute with defroster half on. I've also seen the heater core provide most of the engine cooling under heavy climbing loads, but that isn't an option I would exercise in hot weather. I think my calc is mostly useful for summertime pass climbing at this point... If you want to set a fixed inlet size and leave it alone forever, I think it's a good guideline. ...EDIT... except actually I think my numbers might still be a bit high. I'm sure if I keep refining it I'll get closer.
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When doing straight,steady-velocity highway travel,modern gasoline engines are achieving up to 38% thermal efficiency.
As you add drag reduction your heat flux is going to go down and down as your road load falls lower and lower.And of course your cooling requirements will fall as a consequence as your numbers-crunching is showing.
As long as you can 'open' your grille for worst-case scenario driving loads,or impart a higher static pressure across the heat exchanger (electric fans) you ought to be able to address the full spectrum of loads.
The fixed,concentric bullet valve behind my inlet, is intended as a 'future' active element to optimize cooling air flow (complete shutoff during winter parking,etc.) but since it is not within the KISS design framework must languish until that system is idiot-proofed.