IO-360-A3B6D engine analysis LOP ops

[Scott Aviation]

Hey Guys,

So I've been downloading my engine data since installing my CGR-30P by EI, I have to say what a great engine monitor..Its been installed now for 4 months and am really impressed.  Im hoping some folks can have a look at my attached engine analysis I put onto Mike Busch website Savvyaviator   Im curious what the general thoughts are if my engine data looks good, bad, ugly?  Ive got a good snapshot of when I took it lean of peak.  I notice that in climb. Cyl 3 is hottest. and when switching to LOP it goes to number 1 cylinder and doesnt peak at the same time, even though my gami spread is .1-.2 between 3-2-4-1 normally in that order.  when I fly lean of peak down low and pull the power back to below %65 it likes it and flys great no engine stumbling at all..   I notice when I fly up to 10,000 feet to cross the rockies, and fly WOT and 2400 and pull back to lean of peak it seems to never want to peak before it stumbles and runs rough.. I cant figure out for the life of me why it does this.  I have tried pulling the throttle back a smidge to create some turbulance into the throttle body with no dice.  Anybody else experience good LOP ops at low altitude but struggle to do it at high altitude.???

 

thanks for any input...just a note the engine and fuel injection system are all new.

 

chris

[EDNR-Cruiser]

First of all: I am NOT an expert!
However I find this interesting to test my little knowledge. 

But a question first: what do you mean with "it doesn't" peak?
Each cylinder may show a different EGT = "maximum exhaust gas temperature" (not to confuse with cylinder head temperature) at peak.
My cylinders peak roughly in the same order as yours and 3 shows the hottest EGT, then lean of peak the EGT drops on cylinder 3 and remains rather the same on the other three cylinders (roughly about 50° below cylinder 3 peak EGT).
Remember the shape of the EGT curve? There you go... 

Leaning further cylinder 2 EGT goes down while 1 and 4 don't change and when cyl 3 is about 100°  below its peak then my engine begins to feel a bit rougher - however cyl 1 and 4 are still almost at their peak or just 25° below.
At that point the distribution of fuel has become so uneven in the cylinders that 1 and 4 still generate almost max power while 3 is hardly firing any more - thus the rough "feel".

Depending on manifold pressure, pressure altitude and RPM the EGT peak temperatures vary some... - they are no constants but just showing trends. Without turbo charching you will hardly achieve the same peak EGT temperatures at FL100 as on sea level.

The diagramm you uploaded looks almost "normal" to me... - except that cylinder 1 seems to top out flatter than the others. The spread in CHT seems pretty constant with a 40° spread.
Your cyl 2 is the first to top actually, then 3 which is also running hotter, followed by 4 and then 1. As your cyl 1 is running with more power (i.e. richer) in cruise, the internal pressures are higher also and thus the CHT.
The CHT looks a bit high to my taste in the final stage of climb after minute 10. I would have tried to stay around the 350° mark and probably exchanged some climb rate for higher airspeed and lower CHTs...

[PTK]

Chris, out of curiosity what is the sampling rate resolution on your monitor? I have a JPI and the best I can get is every 2 sec.

I ask because the curves look smoother compared to mine!

[Cruiser]

If all your thermocouple sensors are the same, you need to continue leaning to see how the CHT on #3 behaves when leaned as far as the other three. If it continues to run higher,  I would be looking for baffling leaks to get more cooling to #3. Right now from the image you posted it just doesn't look like it has gone far enough lean to effect the CHT.

it is not uncommon for the IO360s to have one cylinder slightly off compared to the rest in FF. You can play around with injector swapping but it typically doesn't help much. Timing has the greatest impact on changing CHTs.

 

That graph sure doesn't look like a .1 or .2 GAMI spread. Your #3 is definitely the richest. Try the GAMI test at 10,000' next time you are up there. If you can get really LOP down low and not up high you might have induction leaks or spark plug problems.

[wishboneash]

 

Hey Guys,

So I've been downloading my engine data since installing my CGR-30P by EI, I have to say what a great engine monitor..Its been installed now for 4 months and am really impressed.  Im hoping some folks can have a look at my attached engine analysis I put onto Mike Busch website Savvyaviator   Im curious what the general thoughts are if my engine data looks good, bad, ugly?  Ive got a good snapshot of when I took it lean of peak.  I notice that in climb. Cyl 3 is hottest. and when switching to LOP it goes to number 1 cylinder and doesnt peak at the same time, even though my gami spread is .1-.2 between 3-2-4-1 normally in that order.  when I fly lean of peak down low and pull the power back to below %65 it likes it and flys great no engine stumbling at all..   I notice when I fly up to 10,000 feet to cross the rockies, and fly WOT and 2400 and pull back to lean of peak it seems to never want to peak before it stumbles and runs rough.. I cant figure out for the life of me why it does this.  I have tried pulling the throttle back a smidge to create some turbulance into the throttle body with no dice.  Anybody else experience good LOP ops at low altitude but struggle to do it at high altitude.???

 

thanks for any input...just a note the engine and fuel injection system are all new.

 

chris

 

If at higher altitude it runs rough while smooth at lower altitude, possibly the magneto/spark-plug combo issue. Perhaps try a magneto check at 10,000 ft.

[kmyfm20s]

If at higher altitude it runs rough while smooth at lower altitude, possibly the magneto/spark-plug combo issue. Perhaps try a magneto check at 10,000 ft.

I agree, in my experience with induction leaks is that you can run LOP at high alt. and would run ruff at low alt. Ignition systems are under greater stress at high alt., definitely try a LOP mag check at altitude to help rule out some variables.