Running lean of peak and fuel economy

Dan wrote:
On Mar 20, 6:55 pm, Jay Maynard
wrote:


On 2008-03-20, Dan wrote:
The aircraft I trained in a long time ago didn't have such fancy
instrumentation. One leaned the engine in cruise by the tried-and-true
method of leaning till it ran a little rough, then back rich until it ran
smooth again. This worked, but wasn't exactly precise.

Actualy, Jay, that method is stil pretty good. The engine monitor helps
you be more accurate, but thats about all. My favorite graybeard pilot
just slowly yanks the mixture until he sees about a 5 knot drop in
airspeed. I think he was doing that before there were even CHT or EGT
gauges.

The JPI manual -- while presented in a convoluted, rambling way -- is
very helpful.

I beg to differ. Its downright wrong in several ways according to
some folks (sorry, I can't be more specfic, I don't remember the details).
The links in Matts post (especially the pelican perch ones) will be
much more useful reading.

JPI mentions GAMInjectors as required for the Lean of Peak method.

Which is just one way the JPI manual is flat wrong. The big radial engines
in airline use were run LOP as SOP. That was way before fuel injection.
I can run my carbed E-225 LOP (although only about 20 degrees before it
gets too rough) as can lots of other carbed engines. It may take some
induction tuning or playing with carb heat to make it happen though.

The argument is that lean of peak the temperatures are cooler than
peak and burns less fuel. Thus you prevent heat damage (which you
might see at peak or even slightly ROP) and save $ on 100LL.

--
Frank Stutzman
Bonanza N494B "Hula Girl"
Boise, ID