Mogas: what happens to EGTs?

Stu Gotts
shared these priceless pearls of wisdom:

-Before this morfs into how the innkeeper built his homemade fuel
-pumper, I thought I would post the answers. I'm surprised many more
-didn't take a shot at this but then again, it's not regular hangar
-chat. How well did you do?

The innkeeper built his homemade fuel pumper after seeing the plans that a
sparky gave him at an Oshkosh forum, but to the point...

Now to the point -- I thought you said that your source had DONE the experiment
and HAD data. People who have been there and done that don't say "SHOULD" and
"PROBABLY", they say "DID". I think you've dicked the problem without hard
data.


Jim


-
-EGT = Exhaust Gas Temperature
-CHT = Cylinder Head Temperature
-ROP = Rich of Peak
-LOP = Lean of Peak
-(and I should have listed this earlier, sorry!)
-
-
-The lower octane should cause a faster overall burn time and short
^^^^^^
-interval to peak pressure - - and that should result in lower EGTs.
^^^^^^
-
-For the same reasons, the peak pressure increase should cause higher
^^^^^^
-CHTs.
-
-And the horsepower ?? It probably would not change much... 1-2 % .
^^^^^^^
-
-The overall effect is the same as if you had improperly advanced the
-timing 3-7 degrees.
-
-Regards, George
-
-Contact George at gami.com for any further explanations.
-
-
-
-
-
-
-Ok... little MOGAS quiz for you.
-
-You run the Left tank dry and fill it up with premium unleaded car
-gas.
-
-Right tank has 100LL.
-
-Takeoff on the RH tank and climb, level off, and set up the mixture
-for
-cruise flight. Either ROP or LOP. Your choice.
-
-
-THEN, you switch to the LEFT tank. You change nothing else.
-
-Later you download your JPI and plot the data.
-
-1 What is it going to show happened to the EGTs when you switched
-tanks?
-
-2 What is it going to show happened to the CHTS when you switched
-tanks?
-
-3 (not in the JPI, but: ) What is the airspeed going to do? Increase?
-Decrease? Stay the same?
-
-Why?
-

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