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Top Overhaul IO-540 LYC

Chippster1

Active Member
I am having the disappointing experience of having my cylinders replaced on a 900 hr Aerosport Power engine at 900 hrs.(Lycoming clone IO-540)
It was originally built with 9.5:1 ECI Titan cylinders. It is now in the shop getting brand new Millenium cylinders with the standard 8.7:1 comp ratio. The engine shop called me today and asked if I wanted to put in 9.5:1 pistons again, but I was wondering if the increased compression was the reason the ECIs were toast at 900hrs.
I would love to hear everyone’s opinions on the pro and con of increasing compression. The engine has 1 standard Mag timed to 20, and a light speed ignition module set at Aerosport when it was built.

Ted Chipps
RV10 N498EC
 
Seems quite unlikely to me that increased CR would cause excessive wear requiring replacement. For more likely to be a different issue. You didn't state the failure or symptoms, so can't offer more.

Increased CR is free power, but is not without risk, most of it comes with decreased detonation margin. Also requires more amps to spin it at start up. Plenty of info available via search.
 
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Oil consumption now at 1 qt/ 2 hrs
And compressions in the 60s
Suspect broken rings
Will let you all know when cylinders come off on Monday
 
Oil consumption now at 1 qt/ 2 hrs
And compressions in the 60s
Suspect broken rings
Will let you all know when cylinders come off on Monday

If that is the case, hone the cylinders and replace the rings. If that is all you know now replacing cylinders is swatting a fly with a sledge hammer.
 
A cost reference point..

I just IRAN’d all six jugs for $4800 including new pistons, piston pins, rings, honed, two new guides and all seats lapped.
 
900 hrs

To all those who asked
Here is a piston and cylinder from #5
 

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Unhappy piston

I can't comment as to the cause of that unhappy looking piston but I sure hope my top end will last longer than 900 hours.
That is quite a "sunburn"
Any idea as to what indications you had to see this coming, if any?
Do you have engine data logging to look back in time and see what stands out?
Just curious and sorry you have to spend money at this time.
 
Curious too ... in the world of big block V-8's that looks a lot like high temp detonation, maybe from over advanced timing and high loads. Would like to see the crown of the piston as well. Good luck chasing that one down, we can all learn.

Cheers
 
It was originally built with 9.5:1 ECI Titan cylinders.

I have 9.5:1 ECI cylinders in the IO-360 powering my RV-6. Main difference is my oil consumption is like 30 hrs/qt and compressions are all near 80. But I've read enough about the ECI Titan issues and AD that posts like this one have me concerned. You can bet I'm watching the oil usage and G3X engine log data pretty closely.

--Ron
 
Did you ever check the Lightspeed timing with a light? I know of Lightspeed MAP sensors that failed, resulting in actual timing being at 40+ degrees regardless of engine MP or RPM.

Carl
 
The barrel/jug/cylinder wall sure looks like delimitation of the coating. Factory defect - replace. Nothing to do with the compression ratio.

All pistons, crown, and skirts should be inspected as a whole before rendering any judgment on them. The deposits look soft, not hard.
 
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