lean of peak

[awash2002]

I've have not been able to get the 182 to run smoothly at LOP mixture it runs smooth at Peak EGT but I've not been able to get it to run comfortably Lean Of Peak

[Oracle427]

That sounds realistic for a standard 182 that hasn't had tuning of the injectors to ensure that all cylinders are operating at about the same fuel/air ratio when leaned out to this point. Even if tuned, there could be issues with the engine that would result in poor performance when leaning this far.

When we lean in an engine, we are looking for the EGT to rise on the hottest cylinder and leaving it at peak for best economy or enrichening to 50 rich of peak for best cruise performance.

This is a "safe" range as only one cylinder is running hottest and the rest are assumed to be cooler and in many cases much cooler than the hottest. I generally find a spread of 100 degrees between the coolest and hottest on the engines I'm flying these days and that is a very big spread. There is plenty of power being produced by all of the cylinders on the rich side of curve. The excess fuel is mostly wasted while the cylinders produce power.

As we start to make our way to the lean side of the curve the power rapidly drops off on each cylinder. We can get the hottest cylinder lean of peak, but go any further in an attempt to get the rest of the cylinders into that range and the engine will stumble as cylinders start to misfire with the extremely lean mixture. When leaning too far, the EGTs will drop very rapidly indicating that the cylinders are no longer doing much work.

A tuned engine will operated with a small spread between the cylinders at around peak EGT. This way, most of the cylinders can cross over onto the lean side without having some working at full power and others barely working at all.

I don't go LOP in the flying I do, but I do fly an airplane with GAMIjectors. It has a ridiculously flat set of 6 EGT bars at peak. It also exhibits a very pronounced boost in performance when leaning. You can feel the shove in the seat of the pants as all the cylinders are set up to work together at max efficiency.

[AKar]

Unless it has been changed, the A2A runs lean of peak really well. In the simulator, a quick, easy way to set the mixture is to lean until you get this uneven running effect, and enrich just to restore smooth running. I don't remember the figures, but you end up well lean of peak that way, maybe some 100 °F or so.

-Esa

[awash2002]

I'll try that