[sailvi767]

Our engine (eci io360, 10-1 pistons, eci injection, dual lightspeeds) has never been happy running LOP above about 6000 feet. Down low it would run LOP just fine. Up high there was some roughness and a split on when cylinders peaked.
We recently decided to replace the plug wires since we were not sure of age and they could have been near 500 hrs.
We had a set made locally by Scott wires who makes high performance wires for racing applications. He did a beautiful job for half the price of other sources. I also learned a few things from him about ignitions. Who knew dragsters run mags that put out such high power they can fry a set of wires in 2 runs!
With the new wires our engine now is much happier LOP. I will post before and after pics. I was skeptical they would have any effect but they appear to have solved the issue. One boot on the old wires was found to be cracked.
George

 

[RVbySDI]

Before I make a comment, please note I am no expert on others running LOP. However, I do consider myself to be an expert on running MY engine LOP.

My comment has to do with your CHT numbers being displayed. I would not expect your CHT's to be 400+ while running LOP! Another thing I notice with those CHT's is the spread between each cylinder. Your scale does not give a close enough breakdown to see how closely the temps are to each other. Do you have information on exactly what your CHT temps are for each cylinder? In my case, when running LOP in cruise my CHT's are 10 degrees or less from each other. They ebb and flow as one unit staying within that 10 degree range of each other. In your pics it appears cylinders 1 & 3 and cylinders 2 & 4 are close together but the two banks are separated by a fairly large margin of temps with 2 & 4 looking uncomfortably high.

I do see that you are running pretty fast up high and burning around 7.8-8.1 GPH. Even so, I would want those CHT's below 400. In fact a lot lower than 400. Too much written on the temps of CHT's and how the higher temps (400 +) contribute to shortened piston life.

Below is a pic of one of my flights with similar engine parameters to what you show in your pics. The one important main difference being the speed at which the two planes were flying. Make a note that my instrument speeds you see on this picture are all in statute MPH not in nautical miles per hour (KTS). You are flying considerably faster than I was in this pic. That is definitely an important distinction to note in examining the two operations. However, I wanted to point out the CHT's while running LOP in this flight. First off, note the temps are well below the 400 degree temp. I consider that 400 degrees as the bottom temp of the DANGER zone for running LOP. Anything 400 deg or higher means I am at a greater potential risk of cylinder damage so I stay well clear of that threshold temperature when running LOP. The other point is the temp range of all four cylinders. the low is 324, the high is 334. All within 10 degrees of each other. Not as critical as CHT, but you might also note the EGT's are also within a small range of each other. Everything humming along nicely together. This pic does not show it, but on the engine monitor page the EFIS shows me a trend line for CHT's and EGT's for all four cylinders for the entire flight. That trend line is always as if it were one line, even though there are four separate lines, one for each cylinder in that trend graph. Me likey that alot!

As noted concerning the speed, that margin I allow, to stay clear of the 400 degree temp, does come at the cost of airspeed. I do give up some airspeed but then again, I am not in a race when flying. Racing is a totally different environment where one most likely will be pushing the engine to its limits, but that is not my mission. So, I stay away from that operating regime with hopes to keep my engine purring happily along for a very long time while still running LOP and saving fuel. Oh, speaking of that, it is hard to see in this pic but this pic shows I was burning 7.0 GPH on this flight. Slower flight than yours but cooler running engine, 1 gph less in fuel burn and still clipping along around 160 mph or so. If speed were of concern I could still push it up to more like your 8.0 gph but I would still make sure to keep my CHT temps below 400 in doing so.

Just my take on LOP and considering this is all unsolicited input, worth to you just about what you payed for it I am sure.

Live Long and Prosper!

 

[SmilingJack]

This is a great post! If I was to post a picture of my AFS running at LOP it would show the same spread.

I am goijg to take a look at the wires "I" made. It would seem I need to make better ones.

As for the running over 400 CHT, I am not seeing that. Both picurs Re showing nothing about 300 to maybe 340 degrees.

With the AFS CHT is the little white box on that green scale.

But, good info regarding running at or over 400.

 

[sailvi767]

On the AFS4500 the cylinder head temps are the white horizontal bars and that is the only CHT display in the peak display mode. In the normal mode it gives a numerical display also. The green vertical bars are EGT. The CHT's are running right around 310 degrees. Number 1 is always cooler and usually around 295. I do wish in the peak mode gave a better CHT display. ROP we run in the 340 range with those OAT's.

 

[Rupester]

Agree with Steve

I see the same items of concern as Steve. My IO-320 running at the same conditions and altitude (i.e. ~2500 rpm, 21-22" MAP, LOP, 34F OAT) would produce airspeed as Steve shows and CHTs of 320F maximum. Quite often while running LOP in winter, all four of my CHTs are in the high 290s.

 

[SmilingJack]

I dont know how, but there is another way to display engine temps.

AFS had an option to depict the engine parameters in a view that looked like the 4 cylinders of the engine vs. the bar chart.

Maybe someone knows if this is still an option to display, but I just havent been able to find it anywhere in the manual.

 

[Rupester]

On the AFS4500 the cylinder head temps are the white horizontal bars and that is the only CHT display in the peak display mode. In the normal mode it gives a numerical display also. The green vertical bars are EGT. The CHT's are running right around 310 degrees. Number 1 is always cooler and usually around 295. I do wish in the peak mode gave a better CHT display...

Oh, wow. That AFS display is apparently quite foreign to GRT drivers like Steve and I. Only after this explanation did I see the subtle CHT indicators.
Sorry for the confusion.

 

[sailvi767]

I see the same items of concern as Steve. My IO-320 running at the same conditions and altitude (i.e. ~2500 rpm, 21-22" MAP, LOP, 34F OAT) would produce airspeed as Steve shows and CHTs of 320F maximum. Quite often while running LOP in winter, all four of my CHTs are in the high 290s.

That is right where my temps are as posted above. #1 is just below 300 and #4 which is about 315 is the hottest. I would be scared to death if they were 400 at cruise even ROP. I will add that a couple of the plug wires were zip tied together as well as the cracked boot. Wires arc much easier at higher altitudes so I am hoping we have solved our issue.

George

 

[sailvi767]

Oh, wow. That AFS display is apparently quite foreign to GRT drivers like Steve and I. Only after this explanation did I see the subtle CHT indicators.
Sorry for the confusion.

It's not a great display for CHT in the peak mode. I can see why the confusion.
G

 

[RVbySDI]

Yes, I see now. My mistake on the CHT temps. I was looking at the top of the green bar as the CHT temp when in reality your EFIS was using the horizontal white bar as the actual temp. I do like the GRT that displays the actual number right on the display. Regardless, I still will not allow my temps to get close to that 400 deg temp. In fact, the hottest I have ever seen my CHT temps was on a long (3 hour) flight running LOP in 90 F OAT at 4500ft. On that flight my CHT's gradually crept up to the 375-380 mark just prior to landing for fuel. That was not a comfortable flight temperature wise in the cockpit. 3 hours of sweating in 90 F in a confined greenhouse was a bit much for my taste.

 

[RV10inOz]

That is impressive speed and power. 135HP at 9500' is pretty good going.

Or in comparison to a stock IO360 that is 75% power. The 10:1 pistons sure do give you good power and efficiency.

 

[Bob Martin]

Klaus

George,
Glad you figured out a weakness and fixed it.
I'm thinking I read somewhere on Klaus's site that he recommended replacing the wires on a regular bases because he knew they degraded with use and the interval was shorter than I imagined. Just a FWIW.

ps...love the upgrades to Robbie's -6.