0TreeLemur

That's not dissimilar from what I do. I'm just looking for a bit more information. Can you tell me why you choose 2550 rpm? Do you use 2550 at 11.5K too? Why not 2600? I don't fight headwinds. Groundspeed is what the wind gods determine it shall be. If possible, picking a heading can have a much bigger effect on groundspeed can have a lot more effect than engine settings.

%pwr is secondary. First thing I'd like to determine is this: find the optimal cruise rpm for a given MP, given that MP=MP(density altitude) when WOT. I know higher altitude, lower MP, so more rpm required for the same power. But is the same power required, or necessary? Below about 5,000 then we can dial in MP in cruise, but 22-24" is the normal range for me at least. Secondarily I'd like to keep LOP ops out of the red box, that's where the %pwr estimation comes in handy, particularly down low, where I dial in MP. I think the way I run the engine is ok, I'd like to know. What I'd really like is the on airframe data collected by Mooney! Prolly na ga get it. I've written a program that duplicates the Lycoming IO-360-A power curves. It does not include ff as in input. So I cannot solve my problem.

I'd just about bet that the JPI uses that relationship when it knows the engine is LOP.

Having owned both, the ergonomics/aerodynamics of the J win the day. That's why there are all those mods to make a C more J-like. The J cruises 10 knots faster than a C with 20 percent less fuel flow.

Sure it is, but Github is full of code that used to be proprietary. Brave developers release their code so it can be scrutinized and improved upon. That's my opinion. It's not like they'd lose customers. Their product is amazing in my opinion. I didn't buy it for that feature. If it didn't have it that number, I'd just use the tables.

That makes sense. I'd like to see the code...

Great thread- I just discovered it. Like many of the folks that posted here, I'm interested in operating the engine correctly LOP. Probably too interested... My J has an EDM 900, and I've noticed that after I set MP and RPM, the %power displayed on the EDM decreases as I lean with little/no change in MP and RPM. Somehow the JPI uses fuel flow in its %power calculation. I'm wondering how, and how accurate it is. The published Lycoming chart for A6B3D is at "best power mixture" only. Anybody know how it does it?

That doesn't make sense. 180 h.p. on our airframes can't make that happen. I suspect the ASI. Do a three leg and share the results then I'll start believing in miracles. Flew my J to New Orleans today 24 sq. at 4000 ft burning 8.6 gph LOP, and was super pleased to see 142 knots indicated and calculated 150 knots TAS. Your photo shows you were cruising at 5,500 indicating 150 knots, assuming your OAT was 5 C, your TAS was 160 knots! Sorry. I don't believe it.

@Wingover I love the JPI 900. One suggestion. When you calibrate fuel senders in your J as described in the installation manual- after each 8 gallons, give the plane a little shake. Sometimes the senders can get hung up in their motion when static. When my A&P and I performed that calibration I noticed that when we went from 16 to 24 gallons in the right tank, the addition of that 8 gallons didn't change the resistance much as displayed on the JPI in calibration mode. When he started adding the last 8 gallons, I noticed the resistance value jumped.

And turn my J into a giant shrieking whistle!?!

Very clever. I've been thinking about a solution on the J model. I like this, but on the J there is no drain hole. I was thinking about something like an engine hoist, but not so heavy.

It's gotta be a known shop. That's the rub.

I agree with this. From experience, a pre-buy that turns into an annual performed by a neutral A&P/IA is the way to go. As airworthiness items arise, the selling price can be adjusted. A pre-buy that doesn't look in enough detail for those winds up costing the buyer money.

Thank you for sharing. Fantastic Mooney trip!

If you use google to search this site using prompts like: "prebuy site:mooneyspace.com" you will read some very nice stories, and some horror stories. Usually the horror stories start out just like your original post, followed by a bunch of warnings. Sometimes it all works out. It is a fact that wood wings present a unique set of challenges. It is hard today to find shops/mechanics that know much about Mooney's, much less the challenges presented by wood and fabric. Most of them are retired, about to retire, or gone. It is also a fact that a 64 year old airplane with only 2600 hours total time has sat for extended periods. After about 500 hours of sitting idle (3 weeks), the thin film of protective oil on important engine parts such as the camshaft dissipates, exposing metal to air and potentially water vapor. Corrosion can result. It's best to run the engine every two-three weeks, or install an engine dehumidifier. Unless you are independently wealthy and have money to spend on fixing up an outdated antique aircraft, and will enjoy doing so, you will probably not enjoy owning an airplane that you cannot afford to own. If you have the resources and need reliable transportation for regular use, spend as much as you can to get the aircraft you need. We don't buy airplanes to save money. We buy airplanes to save time.

Thanks for your reply Rob. There were a few strikes within 50 NM, but not many. I was mostly surprised because IIRC the WX10A stores strike range & azimuth for the last 256 strikes in memory and re-scales depending on the max. range setting. At both 50 NM and 25 NM ranges, the display showed nothing. I powered it off/on at the 50 NM range and it gave me kind of a funny "+" shaped display on the CRT that faded away. It seemed to work fine at 100 or 200 NM ranges all day. At 100 and 200 NM ranges everything looked fine. Maybe I just don't worry about it? I did have Nexrad up on my iPad, and everything made sense that I was seeing. The controller was Johnny on the spot with some suggested headings to avoid the heavy precip. He sent me towards some nasty looking wx on the iPad that had moved/or died out since the last refresh, which was usually less than 5 minutes. It was a fun trip.

Howdy all. On an IFR trip last week the WX10A stormscope indicated an issue. I was using it to help avoid embedded convection in a broad region of stratiform rain from just west of the Mississippi River and over most of Arkansas. The Stormscope seemed to work fine at 100 and 200 NM range settings, and generally agreed with what I was seeing on FIS-B. However at 50 and 25 NM range it displayed no lightning. There were some strikes within 50 miles according to what I saw at 100 mile range. I'm wondering if this is most likely a problem with the display or the processor? I'm guessing that it is probably the processor. Anyone have any experience with this? The ZME controller I was talking to was extremely helpful in avoidance based on his radar info.

TCL is on the list. I'm based at TCL, and have never (yet) received a bill. Either they don't charge for light GA, or they are saving up the charges to send me a new years present!

The person who posted the video believes that under hist test conditions, intermittent wetting and evaporation of G100UL seems to concentrate the component of the fuel that is more aggressive towards paint. Sadly, that's a Mooney with a leaky tank.

I agree that it is weird to have to ask ATC for clarification. Standard phrases should be the only thing that comes out of their mouths when giving us direction. It's their job! The use of non-standard phrases creates all kinds of uncertainty. After a handoff last Saturday from Ft. Worth Center to Memphis Center, a controller said to me "3514 Greenville Altimeter 3024". That left me in a lurch, puzzling over what the heck than meant... I should have spoken up with something- I'm still at a loss. Maybe "repeat last message"? A minute later he asked me if I was squawking 3514. I think he forgot to key the mic at the beginning where he said "Reset transponder..."

This morning I saw an article on AvWeb saying that the FBO in Tupelo, MS, has received a shipment of G100UL. That's about 1 Mooney hour from my home field and the first outside California. I'm G100UL curious, but the left tank in my J leaks when over about 15 gallons and in that condition I'm unwilling to think about putting it in until this potential compatibility issue is resolved. I don't want to be an experiment... BTW I've contacted the company that resealed the tanks in 2018 about getting it patched, but haven't had a chance to get the aircraft to them.

Low flow in the Mississippi River seen this evening. An upstream moving tow dodging many exposed river training works under a cold sky.

I don't know about legality- but it will fly and I'd bet you won't be able to tell the difference. BTW, I've heard tell from an anonymous source that a M20J will fly without the belly panels, and its hard to tell except for the increased noise. It wasn't me.

Agree. Lycoming documentation is inconsistent over LOP ops. The power table that @PT20J posted for the M20J says that best economy occurs 25F ROP, while the O-360 chart he provided in his last post shows the best economy range LOP. Aside from fuel injection, they are in many ways the same engine, right? I'd wager that nobody would recommend running an engine 25F ROP except at MPs that result in less than about 70% power.