The "S" associated with T (i.e. TSIO-540) means supercharged. Turbo is not the
only method of supercharging. There have been engines built with the
supercharge compressor being engine-driven, electric motor driven, and
wind-driven. Turbo (driving the supercharger off the exhaust gas stream) is
just the currently popular way of doing it.

"E", so far as I know, is just an archaic way of designating "Engine" before we
had the current "O" for opposed and other minor variants. However, I am not
absolutely sure on this one.

Jim




"jharper aaatttt cisco dddooottt com" "jharper aaatttt cisco dddooottt com"
shared these priceless pearls of wisdom:

-I know what *most* of the letters that show up in engine designators
-mean (e.g. TSIO-540, AEIO-540), but there are two I can't figure
-out and can't find any information about, viz S and E. They seem to show
-up with T (turbo) and A (aerobatic/inverted) respectively, but that
-do they actually mean?
-
-Thanks,
-
- John


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com