IO-550 LOP Operations

[PMcClure]

OK, so I've only owned my 2000 Ovation 2 for a little over a month now.  This past weekend I decided to experiment with the ROP/LOP issue while on a 2 hour trip at 8,000 ft.  I don't have the really cool G1000 panel shown at the beginning of this thread; just the regular old Moritz gauges.  I had the RPM at 2300 and the MAP at 22".  I kept gradually leaning the mixture until I got to 1600 degrees.  Redline is 1650.  I didn't really want to continue leaning because I don't know if I entirely trust the Moritz EGT gauge so I chickened out and enrichened the mixture 50 degrees to 1550 thinking that in case the peak was actually 1600 degrees (but I was a little afraid to chance it any further) I would at least be 50 degrees ROP at best - maybe/likely more ROP than that.

 

My first question is what peak EGT do you normally expect to see with an IO-550 at 8,000 ft?  

 

Second, do you think my EGT readings might have been in error?  I don't have the individual cylinder EGTs like the person who started this thread so I don't know whether the EGT reading I have turns out to be an average or is more reflective of the highest EGT cylinder.  

 

Any comments would be appreciated.

You don't have an EDM-700 in your ovation? The Mortiz prop is further down the exhaust and doesn't give you a very good read on true EGT. If you don't have one, invest in an engine monitor to read individual CHT and EGT. You'll pay for it in saved gas and maintenance. 

[carusoam]

The ship's single EGT in the O is on one side after the pipes combine three flows...

It is an intelligent place to put a single gauge... Works well for quick/rough control of mixture during climb.

It's been 20 years since JPI came out with a modern device to measure and graph all six CHTs and EGTs at one time. This really works well for slow/fine control of mixture defining where peak is on each cylinder....

Tell me about the EGT red line you have? I have to look that up...

So, you fly an O and are not familiar with LOP in the bird yet....

Suggestions....

POH has LOP guidance to follow based on factory testing.

APS has LOP guidance to follow based on the IO550 in their lab.

Mike Busch Red box theory for everyone else.

Experiment in cruise at high altitude, this keeps HP below 65% (red box theory).

Expect that the IO550 will smoothly run at 50 dF LOP at high altitudes.

At lower altitudes it can run closer to 100dF LOP.

I have stock injectors that are well balanced. The engine leans smoothly until it stops running...

If there is any dough left in the aviation account, get a JPI, EI, or Insight it is like having a window into the operation of the power plant.

If there isn't any dough left, there are many available on the used market make sure it is for six cylinders...

Enjoy,

-a-

[PhredPhantom]

Thanks for the comments so far and I welcome any others.  I plan to do some research on engine monitors at Oshkosh in a few weeks and hopefully attend a seminar or two on engine ops.

[231LV]

Do yourself and your engine a BIG favor and install an engine monitor...it is absolutely necessary in order to safely run LOP. Without it, you will not know whether you have escaped the Red Box where danger for your engine lurks. The Red Box sits around 50 degrees ROP. Once on the LOP side, there really is no danger.

[butchgilbert]

Very cheap asnd easy suggestion:

Since you don't have GAMI's, swap the #5 and #1 fuel injectors to see if that evens out the CHT and EGT. You might be surprised.

I think that for factory fuel injectors the EGT and CHT spread looks pretty good.

Probably better not to fix something that's not broke.

JMHO.

Butch

[tascher]

Thanks for the comments so far and I welcome any others.  I plan to do some research on engine monitors at Oshkosh in a few weeks and hopefully attend a seminar or two on engine ops.

Phred,

As a shameless fuel burning ROP guy, I'm of no use to you on LOP pointers, but as a 2000 O2 driver with an EDM830, I can tell you that it's not unusual to see a 100F spread between the Moritz EGT at the exhaust junction and actual individual cylinder JPI EGT readings. I typically see a Moritz peak reading in the range of 1620 to 1630. The actual peak decision is on the JPI - it tells you. As noted earlier, do it quickly and get it over with. Think orange, because that's the color of your exhaust for the few seconds that you're around peak. At big power settings I usually run a minimum of 100F rich and often throw even more fuel at it than that. As a ROP cruise rule of thumb I look for a Moritz number in the 1500F zip code. I haven't bent or burned anything yet (other than fuel), but have to confess to the same I'm going to break something chicken out feeling that you describe during my first couple months of leaning. I learned about the Moritz probe mounting location and a host of other operational issues at my first MAPASF seminar. It's worthwhile.

Regards,

Tom

[PMcClure]

I ignore the moritz cht and egt gauges and monitor the edm 700.

[tascher]

I ignore the moritz cht and egt gauges and monitor the edm 700.

Completely agreed that the EDM numbers drive decisions, but I don't go quite as far as ignoring the Moritz numbers. The original ship's gauges still serve as useful backups and as a 2nd opinion if something looks squirrelly. I actually like the Moritz EGT as a quick look tool on decent.

[PMcClure]

The problem is that the edm and moritz gauges never match and cht and egt on stock gauges are meaningless to lean or identify problems. Same for any single point probe system.

[Flymu2]

Sorry I didn't see this sooner. I got the good spread with the GAMI's as they sent them. I didn't have to fool with them at all. I have had to do the back and forth in the past. PIA.

[Flymu2]

Also, my Moritz EGT and G3 monitor peak at the same fuel flow, so I can just watch the Moritz gauge for leaning purposes. The absolute numbers absolutely don't matter. The important number is degrees relative to peak.

[Txbyker]

I am currently in my third round of GAMI swaps.  #5 continues to be last to peak.  We have gotten richer twice and it does not move.  Does anyone know if the lack of me ever being visited by the Pixie fairy can have an effect on when the cylinder peaks?  I am thinking of trying real hard to get a visit from the fairy.

 

Russ

[Cruiser]

You should definitely leave the door open for the pixie fairy, but even after the fairy does his work, it will not effect EGT, only CHT. But you will be happier.