sonicjesus t1_jdysf3s wrote
Reply to comment by KingZarkon in Does living in an airplane flight path, near an airport, pose a health risk? What happens to the lead from the jets fuel? by [deleted]
Has nothing to do with wear. Leaded fuel has a very high autoignition point that prevents knock. Modern fuel uses alcohol, but engines designed for alcohol free fuel are dangerously unreliable.
Modern computer controlled engines mange knock with alcohol added fuel, but when you're ten thousands feet in the air you don't want issues.
KingZarkon t1_jdzwod4 wrote
>Has nothing to do with wear. Leaded fuel has a very high autoignition point that prevents knock. Modern fuel uses alcohol, but engines designed for alcohol free fuel are dangerously unreliable.
Turns out, it does both, actually.
>Lead allowed the development of higher 'octane number' fuel (the higher the number, the greater the resistance of the fuel to uncontrolled burning in the engine, or 'detonation'), and was also discovered, later, to have the property of protecting valve seats from wear.
As for knock, you could just go all the way. E85, for instance, doesn't detonate, period. You can run the timing all the way to TDC and be fine. Would need bigger fuel tanks, though, so that might cut into payload a bit.
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