Originally Posted by
Lake1952
Speaking of fuel. I am fairly certain that those radial engines were not originally designed to burn today's available 100LL. What about that?
What about it? Not sure about the dash number of the 1820 on B-17s. Many of them were certified on 91/98. The current blue 100LL is still 100/130 octane just without the lead. Tetraethyl lead is a lubricant added to the fuel. The fleet of R1820s, R1830s and R2800s in the US has been running on 100LL for decades. We were limited to a few less inches of MAP and lost 100 HP using 100/130 or 100LL in a 2800 instead of 108/135. In the 1820-80 series engines, which were a later variant than what’s on a B-17 I seem to recall it was 50 less HP a side.