Walter Atkinson: If you are LOP on the cylinder with the EGT probe and the engine is running smoothly it means that your method is spot on and you DO KNOW that all cylinders are LOP.
How can you be sure all cylinders are LOP just by what EGT you see on one cylinder?
john deacon
:
Which begs the question. How well balanced are the F/A ratios (assuming good ignition, no induction leaks) in the average Lycoming O320 O360 IO360?
Too non-specific. That's like asking "How much does the average blonde weigh?" There may even be an answer, but it doesn't tell you anything about the blonde you're with!
Actually I disagree. I would think the average Lycoming is far more conforming than your average blonde, otherwise the FAA might have something to say.
Because these engines are being produced to a "conformance standard" (for want of a better term) I thinks it's entirely reasonable to expect there is data on how good or bad the F/A ratio spread is. As you rightly pointed out the average doesn't tell you anything about the engine you are flying but it will give you some confidence (or not) on whether or not you have a good chance of running LOP in an aircraft without the need to find out an optimum carb temp etc..
The reason for my question is most of the pilots I know fly behind Lycomings, and in many cases not always the same aircraft. None of these aircraft have any EMS systems fitted. On this thread and others like it we keep hearing about the benefits of LOP. I don't dispute those benefits. However I did question the practicality of running LOP for many pilots flying behind a 4 cylinder Lycoming.
When I asked how how practical is LOP for the average pilot flying a C172 or PA28 or anyone flying a four cylinder Lycoming.
Walter said
Walter: It is very difficult to find this optimal carb temp without and EMS, but with one it is very easy.
In the IO engines, the F:A ratios are balanced by tuning the injectors (GAMIjectors).
Which to me says it's not practical, yet John Deacons says
It takes only a little bit of knowledge.
Which is it?
Walter: Dexta:
***I have a C172 with the O320-E2D, ............***
If you are LOP on the cylinder with the EGT probe and the engine is running smoothly it means that your method is spot on and you DO KNOW that all cylinders are LOP. If the engine is smooth, the F:A ratios are reasonably well balanced, you have a good ignition system and no induction leaks. Everything is fine. If all cylinders are not LOP, your six little engines running in tight formation sharing a common crankshaft will be running rough since they will be making different HPs.
Are you and Dexta talking about the same model of engine here?
In an earlier post
Walter Atkinson: For a growing number of carby pilots in the US this is becoming standard operating procedure. Each carbed engine has an optimal carb temp that results in the optimal F:A mixture being delivers equally to all cylinders. This temp is actually given in many POHs (often in the fine print!) Once this temperature is identified, it becomes very easy to set the carb temp to that value and have very good fuel vaporization which results in even F:A ratios and the ability to run the engine much smoother across the entire mixture spectrum. For example, in most 182s, the optimum carb temp is 10dC. Each aircraft type tends to have it's own optimum value. This was once considered standard operating procedure on carbureted engines but the technique was lost. It is very difficult to find this optimal carb temp without and EMS, but with one it is very easy.
Does this apply so much to Lycoming engines. On another site I've read that because of the way the Lycoming induction system is set up there is a natural heating of the carb and application of carb heat has no effect in at least some installations. In other words the Lycoming induction system lends itself to naturally aid vapourisation unlike in a Continental set up where there is no natural heating of the induction system.