Lean of Peak Engine Management


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  • April 9, 2023 at 6:54 am #1566

    I have been happy flying my Lycoming IO 360 M1B at cruise lean of peak for a number of years now after reading John Deakin and Mike Busch articles. My CHTs run quite happily at 71-73% HP ( Dynon Sky view monitoring) with CHTs in low to mid 300sF.

    A respected LAME told me that this was ok in the US where Avgas has high lead levels, but here in Australia because we have LL Avgas, this is bad for the valve guides and will lead to early engine failure. I emailed the sales/support manager at GAMI and he suggested that the only reason lead was in Avgas was to increase its octane rating and nothing to do with lubricating valves and valve guides. He suggested we in Australia with LL Avgas should not be different to the US.

    Is there a “ qualified” Australian with experience in this area to give us more advice. I know this topic will potentially generate a lot of comments. I’m interested in facts. I intend to keep flying LOP at cruise as per authors above. Jeff Rowlands Vic

    April 15, 2023 at 12:54 am #1585

    This is complete and utter garbage.

    I am happy to discuss this with you, directly and I suggest you join the list for the Advanced Pilot Seminars class that myself and Andrew Denyer run here. This is the class started by GAMI and John Deakin.

    As much as this sounds cocky, nobody in Australia has done more with Dyno testing of the unleaded avgas G100Ul than me, so I know a few things about this topic.


    The sooner we get TEL out of Avgas the better. The USA spec fuel is identical to ours. Mostly 100LL.


    I assume John-Paul Townsend at GAMI replied to you. He would be 100% correct.


    LAME’s are well meaning but are not qualified to comment any more than your cat. Sounds harsh but it is true.

    You can email me at davidbrown@advancedpilot.com and I will happily help you out.

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