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M20C STCs

aajones5
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DXB Grand Master

DXB

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I have a '68C as well.  Which mods do you have now?

201 windshield (7-8amu) and 201 cowl ($$$$$) bring the biggest speed gains supposedly.  I put in the 201 windshield and think it's nice, though not 8amu nice perhaps.  I will likely put in Sabremech's more economical version of the cowl mod when available. These mods yield some benefits beyond just speed.

On the cheaper end, flap gap seals and brake caliper reversal supposedly yield a tangible benefit.

On the really cheap end, meticulously waxing the leading edges yeilds a bit of speed. So does some weight in the back  to push CH toward the back of the envelope. No STC or 337 required

Shoulder harnesses add zero speed but help keep you from dying, which is nice. I'd say that's first on list if you dont have it.

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carusoam Grand Master

carusoam

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Go see Lasar website...

(You have had) Good luck if you find the mods affordable.

Don't be surprised with how much they can cost.

Installation is extra.

Getting an E's engine with a 201 windshield would be my favorite C mod...

Competing with Urs'  Swiss M20C instrument panel would be my favorite challenge!

Dev and Hank have great M20Cs and don't mind sharing some detail...

Best regards,

-a-

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blurceo Rookie

blurceo

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On 3/14/2017 at 9:01 PM, aajones5 said:

I've got a 1968 M20C with some mods already on it, but I was wondering what are some STCs that y'all highly recommend and what kind of prices could I expect on those.

Thanks

 

My 20C has everything in the book done on it. Has the J model cowling, all of the flap and gap seals, smooth belly (i think), and the 201 yoke controls.  This is my first Mooney so i don't have a good baseline on what it's done for top speed. But by the other Mooney pilots that have flown with me say it's a decent increase. 

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aajones5 Enthusiast

aajones5

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It had several mods on it when I bought it, I'd have to go back through the logs to see exactly what they are but I know I have a 201 windshield, the smooth belly, and the flap gap seals. I think I have the aileron seals and the cowling mod, but I'm not for sure. If the cowl helps with cooling I probably don't have it as I do run hot on climbout

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carusoam Grand Master

carusoam

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Not sure if your cowl is modded...?

Look at other Mooneys. Plenty of avatar photos and photo galleries on MS...

Many of them have not been changed. Others have been closed up, below the centerline of the prop. A few have changed cowl to something newer.

Still not sure... post a photo.  We are pretty good about helping out.

Best regards,

-a-

Edited by carusoam
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Hank Grand Master

Hank

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Your C looks like mine, except for the color. 201 windshield, 1-piece belly, guppy mouth closure. Believe it or not, you have the cowling with better cooling than the stock one . . . But @Sabremech has a new nose that he's working on that provides improved cooling, gets rid of the doghouse and adds a few knots.

The best thing you can do for cooling while waiting on this nose mod is to refurbish the doghouse on top of your engine. Make all of the parts fit tightly, repair all cracks and fill all gaps. The difference is amazing . . . There are many threads here discussing options, methods and results, with detailed photos. If you can't find them in the search box, try googling "doghouse repair mooneyspace" and see what you find.

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carusoam Grand Master

carusoam

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To answer AAJs question of does he have the cowl closure...?

That is affirmative... that fancy sheet metal that approaches the bottom of the spinner has been changed in for the much larger opening that is no longer there...the generator belt is hiding behind there...

 

Other things you see in the front of your cowl are...

1) Landing light

2) The air filter

3) The oil cooler

4) that tiny one inch hole in the center... that connects to the generator to supply cooling air.

 

Best regards,

-a-

 

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carusoam Grand Master

carusoam

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It is a square-ish box under the exterior cowling.  Often black in color.

Open at the front, pressing air down through the cooling fins towards the cowl flaps.

Old dog houses acquire many leaks, cracks, missing parts and holes....

Sealing each offender helps the cooling.  Small openings that don't belong allow pressure to escape and the cooling airflow decreases a bit each time....

As you Learn to take the top of the cowling off, you will immediately see the dog house.  :)

The side cheeks are pretty easy to remove as well. Take a look under there the cylinder heads, and spark plugs are there.  The oil return lines from the valve covers are worth taking a look at early on... expect that you might find a history lesson of every type of hose clamp ever designed in the past 50 years. Or your previous owner took care of a lot of things...

Best regards,

-a-

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Hank Grand Master

Hank

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56 minutes ago, aajones5 said:

it seems crazy to me that they're making the intake hole smaller and smaller and it improves cooling

That's the beauty of CAD design and numerical computation of fluid flow. The original opening showed during tuft testing that airflow reversed and came out the front . . . slowly. Which provided very poor cooling. Everything that comes in  the front needs to go out the cowl flaps, and the opening is just too big. Sabremech also eliminates the doghouse and the carburetor chin, devised engine baffling to take its place, which smoothed out the flow allowing more air to go in. So the inlets had to be reduced again . . .

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