MOONEY M20C RANGER AIRSPEED INDICATOR?

Question

I have a 1968 mooney and want to get the mods put on it so i can go faster. i have a few problems though. everybody says how fast mooneys go and other ads ive seen say their mooney goes 160 knts or 170 mph so on and so forth. my mooney cruises at 150 mph at 8000 ft. (you can check out some of my flights on flightaware.com n6784n). one problem i found on my last flight is the pressure at 8000 ft keep my mp at 21 inches of 2300 rpms. i want to cruise at 2300 rpms and 23 in mp but when i push the throttle in it just comes back out to 21 inches. whats up with that? ive tried to lock the throttle to no avail. the other issue is my airspeed indicator says not to exceed 150 mph in rough air. i dont know bout you guys but i get headwinds going both ways and its always turbulance up there (my luck) so im scared if i spend all this money on the mods i wont be able to really take advantage cause ill have to keep my power back!!! what do you think?

Tracy L · Accepted Answer

Actually sounds about normal for a 20c BUT you may be able to squeeze some more out of it.
Here is a good post about speeds on the M20C http://www.moapilot.com/dcforum/DCForumID1/60.html  

Do check the speed against GPS etc. Airspeed indicators do need calibration and can be indicating wrong.

One thing that CAN make a very big difference is to have the rigging checked.  Just a slight "out of rig" can cost several mph loss of speed.  Get someone who knows Mooneys well to check it and rig it correctly. 

On a noramally aspirated aircraft seeing 21 inches of MP at altitude is not all that unusual. What MP can be produced is totally dependent upon the engines condition. The more hours on them the less likely they are to be able to produce the full rated output. A normally aspirated engine operates most efficiently with the throttle full open whatever MP it produces is what it produces.  Running at 2500 rpm is probably a better idea you may find the engine is smoother and you will pick up some speed. Running "square" isn't always the answer.
Here is a good operating article about all Mooneys http://www.mooneypilots.com/mapalog/cruisepower.html

Don't be too fast on setting cruise power, once you level off, leave everything alone for a few minutes and let the aircraft accelerate to its full potential, then reset for cruise flight.  Do be sure to lean on the way up and once adjusted for cruise lean for cruise! failure to lean will keep power from being produced and will burn a more fuel.  If you have a full engine monitor, consider "lean of peak" operations. There are lots of articles on lean of peak and the savings as well as temps are usually better. You do have to have someway to monitor and know what all cylinders are doing so a full monitor is required for lean of peak.

? · Answer

Hi: I also own a Mooney and what you describe is perfectly normal.
I get 24" at sea level and at 8,000 feet i cant get past 21" either at 2500 rpm.
As for the lean of peak, there are many schools of thought on that.
I prefer to run a little rich of peak. 
Check out mooneyspace.com
We have a pretty active member board and lots of very knowledgeable people there including guys that work for the mooney factory.
Mooney's come from the factory with just about everything you can do to get the max speed out of them.
There are some cowl mods and one piece belly mods that add a knot or two but most of them are not really worth it in the long run. I have left mine pretty much stock with the exception of the new hartzell top prop conversion that added 5 knots to the top end and increased my climb rate by about 200-300 FPM and the cowl mod.

russ

steve · Answer

I have a 62 c with a j windscreen, nose closure, wing root, flap, aileron and  elevator hinge seals, power flow, brake rotation, super flow air filter and I m sure I m 
Leaving a thing or two out. I get between 170 -180 above 6 or7k

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MOONEY M20C RANGER AIRSPEED INDICATOR?

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