wrote:
On Sep 18, 1:40 pm, Newps wrote:

wrote:

I have the cylinder from an IO-520 here that had been
detonating. The head is blown clean off the cylinder; the aluminum
fractured at the top of the cylinder threads. Things would get very
noisy, shaky, smoky and scary if that happened. Cylinder pressures go
out of sight during detonation, as do CHTs.

That sounds like preignition, not detonation. Detonation is rarly fatal
to an engine.


http://en.wikipedia.org/wiki/Engine_knocking
http://www.streetrodstuff.com/Articl...ne/Detonation/
http://www.sacskyranch.com/deton.htm
http://www.americanaviationinc.com/effectsNavajo.html

Dan


Back to the original post somewhat... I knew about the over squared and
my Lycoming O-360 manual has a chart that shows conditions acceptable to
over square for the same % hp. I tried it last night and set the two
conditions for 65% and leaned. I noticed that the CHT were lower in the
over squared condition rather than the "under squared?". I have a C/S
prop with a redline condition between 2000 and 2250 RPM. Really limits
my choices. Do you folks see the same?

--

Regards, Ross
C-172F 180HP
KSWI