OS 1.60FX detonation in the midrange
05-19-2002, 01:32 PM
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OS 1.60FX detonation in the midrange
To whom it may concern.
I have a OS 1.60FX mounted in an H9 Edge 540. It is fully incowled with the airinlet baffled for extra cooling at low speeds. It is using a slimline pitts muffler with a 18x6 prop. I recently switched my fuel type from 5% nitro to 15% nitro both are the Hobbytown Supreme brand manufactured by Wildcat. The engine started experiencing detonation at half throttle and a bad lope at idle. This all dissapeared when I went back to 5% nitro. I was just wondering if you have experienced this with this particular engine. Most people on this forum say the engine runs great on 15%. I guess you want little on the history of the engine too. The engine was broke in per the manual and after a gallon and about a half of fuel it experienced a runaway condition where the engine backfired in a vertical hover causing the prop to come loose and the engine to unload at full throttle. The engine ran at extremely high rpm for a few seconds before I could get it shut down. After the incident I checked the engine and it seemed fine. I believe this runaway was caused by using an A3 glowplug in the engine so I went back to using a OS #8 plug. It was alittle after this that I changed to 15% fuel and experienced the detonation and severe lope.
I have a OS 1.60FX mounted in an H9 Edge 540. It is fully incowled with the airinlet baffled for extra cooling at low speeds. It is using a slimline pitts muffler with a 18x6 prop. I recently switched my fuel type from 5% nitro to 15% nitro both are the Hobbytown Supreme brand manufactured by Wildcat. The engine started experiencing detonation at half throttle and a bad lope at idle. This all dissapeared when I went back to 5% nitro. I was just wondering if you have experienced this with this particular engine. Most people on this forum say the engine runs great on 15%. I guess you want little on the history of the engine too. The engine was broke in per the manual and after a gallon and about a half of fuel it experienced a runaway condition where the engine backfired in a vertical hover causing the prop to come loose and the engine to unload at full throttle. The engine ran at extremely high rpm for a few seconds before I could get it shut down. After the incident I checked the engine and it seemed fine. I believe this runaway was caused by using an A3 glowplug in the engine so I went back to using a OS #8 plug. It was alittle after this that I changed to 15% fuel and experienced the detonation and severe lope.
05-20-2002, 12:30 PM
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Mixture Setting
Detonation can also be caused by a mixture setting which is too lean. You may want to richen your low end a couple of clicks when using the higher nitro fuel. It is possible you may have some internal damage from the overspeed when you lost your prop.
Also, backfires are usually caused by too lean highspeed needle when at above 1/2 throttle. The fact that your backfire/loss of prop and an engine unloading occured when you were vertical leads me to believe that you leaned out when you went vertical. You should be about 400 rpm shy of max lean rpm on your high end to ensure no leanouts when vertical or when fuel tank decreases.
Good luck.
Also, backfires are usually caused by too lean highspeed needle when at above 1/2 throttle. The fact that your backfire/loss of prop and an engine unloading occured when you were vertical leads me to believe that you leaned out when you went vertical. You should be about 400 rpm shy of max lean rpm on your high end to ensure no leanouts when vertical or when fuel tank decreases.
Good luck.
