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Permalink Reply by John Austin on December 27, 2020 at 3:48pm

I understand they only work well at higher altitudes.  Since I'm flying "low and slow" in my STOL 750/Jab 3300, I switched from the Bing to the Sonex/AeroConversions' "AeroInjector" throttle-body carburetor so as to gain a mixture control - works great!

John

N750A

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Permalink Reply by Stephen R. Smith on December 27, 2020 at 6:07pm

I have been using a HACMAN on my Jabaru 3300 powered 601XLB for quite a few years and around 2,000 hours. I use it primarily for economy cruse when operating lean-of-peak. I use it at any altitude when I can. There are times when I can't, for example when the plane is heavy on a hot day. I that situation I my still use the HACMAN to lean somewhat but not lean-of-peak. When operating above about 12,000 feet there is not enough vacuum available with my setup to get lean-of-peak but I still lean. I don't operate lean-of-peak at high power settings. At altitudes above around 8,000, RPM will be high to maintain the needed thrust, but power output is down so lean-of-peak is just fine.

I have alarms set for EGTs that are too high. I avoid the combination of high EGTs and high CHTs. I avoid EGTs above 1,425, normally cruising with EGTs in the high 1,300s.

One annoyance is the interaction between throttle setting and the HACMAN. As the throttle setting is changed, the vacuum available to drive the HACMAN changes and the amount of leaning changes. So I tend not to use the HACMAN in situations where frequent throttle changes are needed. I never use it during landing, takeoff or when otherwise close to the ground.

Steve

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