B20 has less BTUs than dino diesel that is why your mileage drops. Now if they made B20 using animal fats it would have a higher BTU content and you would get better mileage.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

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