What/how does compression ratio affect an engine?

See my other post and clue me in to why they sell 100 octane valves for
A-65s and C-85s. Are they a waste of money?

Scott


RST Engineering wrote:

Oh, not this old wive's tale again. THERE IS NO ADDITIONAL HEAT GENERATED
BY A HIGHER OCTANE FUEL.

Jim


--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

On Dec 10, 4:22 pm, Scott wrote:
See my other post and clue me in to why they sell 100 octane valves for
A-65s and C-85s. Are they a waste of money?

See http://www.fsv2000.at/woche/2001_10/conti_sb_m77_3.pdf for a
TCM Service Bulletin about alternate valves for those engines. They
say that erosion problems have been encountered with the high lead
content of 100LL. It's not because the fuel burns hotter; it's a
corrosion issue. If the fuel burned hotter, I would see both higher
CHTs and more power out of my A-65. But I don't. You need to do some
research on Octane Ratings and Detonation. Google those.

Dan

Let me reccomend a book. It's very old but packed with aero engine
knowledge. It's historically significant and a good read. Read it and
you'll know more about airplane piston engines than you could imagine there
was to know.

"The High Speed Internal Combustion Engine" by Sir Harry Ricardo.
See: http://www.ricardo.com/ricardoStore/...t.asp?P_ID=149 (1968)

(In this case, "High Speed" refers to MPH and not neccessarilly RPM.)

Sir Harry was a British mechanical engineer whose most significant work was
between WW1 and WW2. He championed the sleeve valve engines that were
developed into the Bristol Centurion but his most historic work was on the
Rolls Royce Merlin. He also worked on the last generation of high power
piston engines like the Napier Nomad and consulted with all the US engine
manufacturers. He is a towering figure in the history of airplane piston
engine development.

His work with high octane fuels, supercharging and high compression ratios
is has been acknowledged as a major contribution to the Allied victory in
WW2.

Bill Daniels