jay
New Member
Posts: 1
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Post by jay on Mar 30, 2019 10:57:46 GMT -9
I'm in interested in the following on how members operate their engines:
1. % Power at Cruise - 65% or 75%
2. Does anyone run these engines LOP? If so, at what power settings?
Any LOP power charts to share?
Jay Neely
Panther Conversion
Savannah, Ga.
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Post by tinstaafl on May 21, 2019 9:53:09 GMT -9
I've been running a Colemill Panther converted PA31-325 with 350HP -J2B LOP for about 10 years, and a PA31-350 Panther I started flying a year or so ago. They both run cooler than ROP.
I use 33"/2300 or 2400RPM. Fuel flow less than 14GPH/side, typically 13.5-13.8GPH. This keeps CHTs under 400deg with cowl flaps closed. In the Navajo I get 170kts +/- 2 kts. In the Chieftain slightly slower.
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Post by klausnw on May 21, 2019 17:05:02 GMT -9
Lycoming covers this topic with statistics not recommendations. I personally (recommend), fuel is very cheap  Short term you saver $20 bucks an hour, long term the engine becomes less reliable. www.lycoming.com/sites/default/files/Fuel%20Mixture%20Leaning%20Procedures.pdfI maintain commercial air-taxi aircraft that fly very minimum 500 hours/year and the LOP does not work for these engines. If you only fly a hundred or so hours each year...?. it probably doesn't matter anyway. |
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Post by anatole on Jul 28, 2019 2:53:34 GMT -9
33” 2300 14.5GPH in a Chieftain with J2Bs, about 80dF LOP. Using CHT as a proxy for ICP this is about the same as running 31” 2100 20GPH (150dF ROP) no intercoolers  at 7,300lbs we get about 162-165KTAS <10,000ft cowl flaps closed, average CHT 330dF but usually limited by No3 on both engines being a ridiculous 370dF while No6s are sitting at 280dF! its nearly 5 knots slower than ROP, but fuel savings are huge and compared by the typical shift of 4 minutes in ETA. We fly long legs in outback Australia with fuel around US$9/gal and more to the point, can carry more payload on same leg. In theory should be able to get at least 15GPH according to the experts but it just does not seem happy there. I partially blame poor baffling on our aircraft or more probably a combination of that and very inefficient cowl design ejecting a lot of cooling airflow straight back out around the spinner and the prop hub extension creating very chopped up airflow leading to uneven cooling air distribution. Just a theory though. klausnw, your statement seems fairly vague, what if I fly 300 hours per year? |
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Post by gsimmer on Jul 28, 2019 4:22:37 GMT -9
Go to the APS course if you don't think these engines can run LOP. The engine they did all their tests on is the Navajo engine. I too have a Panther Navajo with intercoolers. I am running 33.5" 2200 RPM at 15.5 to 16.0 GPH at 180 knots TAS. After the first year of running LOP we borescoped the cylinders at annual and pistons look and valves looked as good as the day they were installed. I am running Tempest fine wire plugs and the Mags need to be running perfect in order to do so. Even with the Panther conversion my #4 and #6 cylinders seem to make it 400 degrees first. That is where I set my fuel flow to. According to the Guys at APS, if I can figure out how to cool those cylinders, I should be running about 17 GPH LOP for best power
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