Fuel Flow and Peak EGT

Matt Barrow wrote:

No such thing will happen.


It will if the leanest is LOP, but one is still ROP.



I don't do that.

"Newps" wrote in message
. ..


Matt Barrow wrote:

No such thing will happen.


It will if the leanest is LOP, but one is still ROP.


I don't do that.

How do you know?

Isn't that the point of a temp sensor on each and every cylinder?

Matt Barrow wrote:
"Newps" wrote in message
. ..


Matt Barrow wrote:


No such thing will happen.


It will if the leanest is LOP, but one is still ROP.


I don't do that.


How do you know?

Isn't that the point of a temp sensor on each and every cylinder?



One of the reasons, yes. But at 75% or less you don't use it for that.

That brings up an interesting point. I think the Lycoming recommendation
previously was 75% power for unrestricted leaning. Lately I have seen 65%
as a recommendation. Anyone have any background on the two different
limits?
I've noticed in my O-360-A1A that certain RPM settings (about 2450 in my
case) get a good EGT balance on all cylinders, and aggressive leaning
produces RPM and EGT drops without engine roughness. Is this what the gami
injected engines experience running LOP?

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Best Regards,
Mike

http://photoshow.comcast.net/mikenoel

Macintosh - We might not get everything right, but at least we knew the
century was going to end.

"Newps" wrote in message
. ..


Matt Barrow wrote:
"Newps" wrote in message
. ..


Matt Barrow wrote:


No such thing will happen.


It will if the leanest is LOP, but one is still ROP.


I don't do that.


How do you know?

Isn't that the point of a temp sensor on each and every cylinder?



One of the reasons, yes. But at 75% or less you don't use it for that.

Mike Noel wrote:

That brings up an interesting point. I think the Lycoming recommendation
previously was 75% power for unrestricted leaning. Lately I have seen 65%
as a recommendation. Anyone have any background on the two different
limits?
I've noticed in my O-360-A1A that certain RPM settings (about 2450 in my
case) get a good EGT balance on all cylinders, and aggressive leaning
produces RPM and EGT drops without engine roughness. Is this what the gami
injected engines experience running LOP?




You have a carb, night and day difference. The key is to get all the
cylinders to peak at the same time on the same fuel flow to each
cylinder. In reality what people see is up to a .3 GPH difference
across the various cylinders. Good enough. Keep leaning and you don't
get the roughness because all the cylinders are running at the same
spot. The roughness comes from one or more cylinders essentially
missing and then really not running at all. I don't have GAMI's and I
can run very nicely LOP.

The majority of sources I have read over the years use 65% as the
maximum power at which unrestricted leaning will not burn the valves
or detonate.. It is the number I use, though with my low compression
engine I probably could go as high as 75%, but why take a chance...
And with a carb I lean aggressively... If I lean too much the engine
will start to shake like a wet dog from uneven power pulses, a smidgen
more lean and it simply shuts down...

denny

Mike Noel wrote:
That brings up an interesting point. I think the Lycoming recommendation
previously was 75% power for unrestricted leaning. Lately I have seen 65%
as a recommendation. Anyone have any background on the two different
limits?

Lycoming has always given recommended limitations on operations. 75% in
cruise was always the common limit for leaning. Other documents have given
lower numbers with the phrase "for maximum service life". Here's an example
from a Lycoming Key Reprint article on leaning :

8. For maximum service life, maintain the following recommended
limits for continuous cruise operation:
a. Engine power setting — 65% of rated or less.
b. Cylinder head temperatures — 400˚ F. or below.
c. Oil temperature — 165˚ F. — 220˚ F.

Available at
http://www.lycoming.com/support/tips...Operations.pdf


John Galban=====N4BQ (PA28-180)

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