How fast can an M20F really go?

[hmasing]

Let's assume we keep the stock IO-360-A1A, but add every speed mod and every tuning out there....

How fast could an M20F really go?  I was debating this with a friend, and my claim is that $100,000 in speed mods and tunings would get me about 5-8 knots at most, so 150 ktas optimistically.  Realistically?  Probably 148 or so.  This makes the speed mods not really worth it, IMHO.

What are your thoughts?  Have any of you successfully modded your M20F to be a 160 knot airplane?

[Hank]

Regardless of mods, Vne = 200 mph. Add tailwinds, that's how fast your F will go.

If your F is limited to 148 KTAS, I'm sorry. My C does that, and I have a 3-blade prop that "everyone" says costs speed . . . . . I have photos on my old phone.

[Shiny moose]

In my 67 F  I get 155 Ktas+ (Book speeds )  68-69 % power 100 ROP,  but I have to be 10-12K, some speed mods! 

[Tcraft938]

Interesting point.  Since I'm an aviation geek and spreadsheet geek I did some quick calcs with some assumptions.  No engine mod, no turbo add, etc.  Therefore, assume same power setting and thus gallons per hour and same time to climb/descend, yes I know some mods allegedly increase climb rate.  So basically we are saying the increased speed enhances the efficiency, it can go slightly farther on the same amount of fuel.  So 142kts v 150kts using 10.5gph $4.50 per gallon fuel, on a 1,000nm trip, one plane takes slightly over 7.04 hours the other 6.67 hrs.  That means one uses $332.75 of fuel, the other $315.   So on a 1000 mile trip the savings is only 22 minutes and $17.75.  That means to make up the $100,000 you would have to fly 5.6 million miles, or fly almost 38,000 hours.  I LOVE the vintage Mooney, but do you think the plane, let alone the mods will survive 38,000 hrs of use?

I think if a rich uncle suddenly said, "I will give you $100,000 for you to enjoy the Mooney", I would either use it to upgrade to a different Mooney, but more than likely not significantly modify it, but figure my next 2200 hrs of flying are at zero fuel cost.  If I put the fuel cost away in savings, at the end of 2200 hrs I could pay to have the engine overhauled and have $70,000 left over.  

Now to find that uncle

[A64Pilot]

At low altitude on my pre-buy flight with everything pushed forward and burning take off fuel consumption of 19 GPH, I got an average of 168 kts ground speed.

‘I thought with mods, an F was just as fast  as a J?

I can cruise at 155 true or so, but I’m usually 22 squared and well LOP and 140 ish kts. I can get even at low altitude 135 kts burning 7 GPH, and while I enjoy speed and sometimes use it to beat weather or something, I’m usually going slower and burning a whole lot less fuel, plus Lycoming even says an engine operated at 65% or lower power will last longer.

‘I have old 1980’s avionics, but I do have a 430 for GPS approaches, but I’m dual ILS, dual comm, what would $20,000 or more of glass give me?

The thing about any Mod is on sale day you won’t recoup most of your money, the converse of that is don’t buy an airplane with the idea of modifying it, buy one that’s equipped like you like, even if that means borrowing a little money, it will be cheaper in the long run

Edited April 15, 2021 by A64Pilot

[Immelman]

Tell yourself 140 and be pleasantly surprised.

Tell yourself 150 and you may be disappointed.

5 knots doesn't make a difference.... except in ego. Time is made or lost with your efficiency of operation and ground time.

Is the air silky smooth and cold you'll go fast. Bumpy and hot and you'll lose speed. Light, heavy... it makes a difference.

Edited April 15, 2021 by Immelman

[N201MKTurbo]

Leave takeoff power on and level off, your F will do ~170KTS all day long. If you don't mind burning 18 GPH in a very noisy airplane.

My old F which only had a cowl closure for speed mods, would usually cruise at 152 KTS

Edited April 15, 2021 by N201MKTurbo

[Marauder]

I've owned my F since 1991. With a 201 windshield, gap seals, step removed, lower cowl enclosure and PROPERLY rigged, I see consistently 152 KTAS with 65% power. Cold winter days, it will creep up to the 155 range, hot summer days closer to 149. These numbers are cross checked using both mechanical means (Aspen reported TAS and TAS calculated using the airspeed from the ESI-500 applying the old factory CAS adjustments and the TAS calculator on the Garmin) and the ground course calculation using ground speeds.

I think the predominate factors that play a role are the rigging, quality of the paint and the health of the engine. When I added the lower cowl enclosure, I don't think I saw much change in airspeed (less than 1 knot) but did see better uniform CHTs.

A "YAHOO!" day below.

 

 

[rbridges]

35 minutes ago, Marauder said:

I've owned my F since 1991. With a 201 windshield, gap seals, step removed, lower cowl enclosure and PROPERLY rigged, I see consistently 152 KTAS with 65% power. Cold winter days, it will creep up to the 155 range, hot summer days closer to 149. These numbers are cross checked using both mechanical means (Aspen reported TAS and TAS calculated using the airspeed from the ESI-500 applying the old factory CAS adjustments and the TAS calculator on the Garmin) and the ground course calculation using ground speeds.

I think the predominate factors that play a role are the rigging, quality of the paint and the health of the engine. When I added the lower cowl enclosure, I don't think I saw much change in airspeed (less than 1 knot) but did see better uniform CHTs.

A "YAHOO!" day below.

 

 

[Ragsf15e]

41 minutes ago, rbridges said:

You guys and your TAS readouts!  I don’t think those Aspens have the IAS to CAS programmed in there, so you can likely subtract a couple kts as @Marauder alluded to.  But yeah, 142ish at gross, 147 kts at ~2500lbs, 150-151 light.  Those are rich of peak, 10,000’, 201 windscreen, cowl closure, mid time engine, 3 blade.

I know you said “stock” engine in the original post, but a rajay turbo on the stock engine is the best speed mod there is.  You can then cruise at FL200 which will get you much better tas in an otherwise stock F.

 

Edited April 15, 2021 by Ragsf15e

[Shadrach]

My  67F is box stock with shall we say less than perfect original paint.  It's an unmolested time capsule that served as a demonstrator for a local Mooney dealership.  I flight plan for 150kts and get it running peak to 20LOP depending on my needs.  It will go faster on the deck for bragging purposes but it's not vey practical. I have seen ~ 160KIAS at low DAs on a cold day which likely corrects to around 156KTAS balls to the wall. 

Edited April 15, 2021 by Shadrach

[MIm20c]

1 hour ago, Ragsf15e said:

I know you said “stock” engine in the original post, but a rajay turbo on the stock engine is the best speed mod there is.  You can then cruise at FL200 which will get you much better tas in an otherwise stock F.

My rajay gives me another 20mph at 14k vs 9k. Personally I don’t feel the extra speed is worth sucking on O2.  Now by FL220 it would really be moving but I’ve never been above 15k in it. It really helps in the climb though...

[gsxrpilot]

It seems to me that an F with all the speed mods that were added to a J, should be as fast as a J. Whatever that is...

[Shadrach]

15 minutes ago, gsxrpilot said:

It seems to me that an F with all the speed mods that were added to a J, should be as fast as a J. Whatever that is...

Likely the case. Maybe a touch better as older Fs are a bit lighter than Js and may do a bit better at lean settings because of the extra 5 degrees of timing advance.  

[GDGR]

I bought my F in September of 2018....

First 6 months I was getting 135-ish Kts max out of the plane (21-22 MP 2400 RPM)

The plane had spent a considerable amount of time outside prior to my purchase, and the paint was rough to the touch. So I polished and waxed the plane.... gained 6 kts.

Last year, I went on a mod frenzy and added:

- LASAR cowl enclosure

- Flap Gap Seals
-Aileron Gap seals
- Rudder Hinge covers
- Dorsal Fin Vertical Seal
- Tail Root Horizontal Fairing

All of these "MAYBE" got me 2 kts.... (Yes I was PI$$ED).... 

A good friend, AME and J owner heard be chirping about my slow Mooney. We spent half a day rerigging the flaps and ailerons, along with a couple other minor items (rotated the exhaust aftward, turned the LASAR tie downs 90 degrees). 

I now have a consistent TAS of 147 KTS. 

[carusoam]

7 hours ago, hmasing said:

Let's assume we keep the stock IO-360-A1A, but add every speed mod and every tuning out there....

How fast could an M20F really go?  I was debating this with a friend, and my claim is that $100,000 in speed mods and tunings would get me about 5-8 knots at most, so 150 ktas optimistically.  Realistically?  Probably 148 or so.  This makes the speed mods not really worth it, IMHO.

What are your thoughts?  Have any of you successfully modded your M20F to be a 160 knot airplane?

1) How fast do you want your F to go?

2) How much do you want to spend to make it ‘worth it?’

3) M20Fs make great forever planes...

4) Forever planes can get amortized over several decades...

5) Doing your best financial engineering...  you can cruise 150+ kts, for a few extra dollars every year...

6) Add the TNer because you can... decide each flight if you want to use it...

7) Share that back with your slower friend...  

PP thoughts only...

Best regards,

-a-

[Raymond J1]

I have always found mine too fast, as I like to fly it and I am always disappointed that the flight is already ending.

[Shiny moose]

I cruise  my old 67F 68-69% using book power settings  down low 5-8K 147 148kts, where is wants to be is 10-13K where I normally get 156-158 TAS Ive done a bunch of 3 and 4 way GPS runs. Thats 67 book speeds but I have gap seals, 201 screen, and cowl closure, rigged very good, paint poor but waxed. I have not touched the elusive 160Kt in level cruise 

[Prestonalton]

Just a general comment, great question and i'm having fun reading this thread. Seems like the mean is around 145ktas.

I'm getting 140-145ktas depending on the day, but my paint is currently atrocious. I'm hoping new paint and proper rigging will help out with that regard. You really make your money on GS though, and foreflight has more than paid for itself with wind speeds at altitude. I fly ~125-150hrs a year and saving 5-10min per flight by choosing the right altitude adds up in money saved.

I've considered speed mods, but would rather spend money on the plane in the air (gas) than on the ground getting worked on.

 

[MikeOH]

My understanding is that the boundary layer is attached to the surface; i.e., it is NOT moving.  If this is true, why would a smooth waxed paint job affect speed at all?

[EricJ]

1 hour ago, MikeOH said:

My understanding is that the boundary layer is attached to the surface; i.e., it is NOT moving.  If this is true, why would a smooth waxed paint job affect speed at all?

My understanding is that it moves, just slower than the further layers.    It slows down even further as it travels along a surface.    This is why Mooneys have flush rivets along the first parts of the wings and fuselage and non-flush toward the tail and trailing edges.    I've noticed this on older airliners as well, the first half or so of the fuselage is flush riveted, the back part not.    I got to see a 787 up close last year and it is flush everywhere, so maybe the construction economics have changed or it is considered more useful than it used to be.

[hobbit64]

Please don't tell any of my Army buddies that I regularly reference the 'Squid Book of All Things Aeronautical Stuff'!

(We'll just keep it between us -- Shhh!)

 

Edited April 17, 2021 by hobbit64

[RobertGary1]

Garmin says I true at 140knots in my F. I’m probably due for some rigging.  Likely too many people have stepped on the flap over the years 

[hmasing]

On 4/15/2021 at 7:26 PM, GLJA said:

The plane had spent a considerable amount of time outside prior to my purchase, and the paint was rough to the touch. So I polished and waxed the plane.... gained 6 kts.

My paint is chalky and won't hold a shine.  :-(  

Paint is my next upgrade, once I re-skin my flaps and ailerons from some visible hail damage.

[carusoam]

Imagine waxing the surface so smoothly... the boundary layer slips off...  

Trying to describe how this works, with the proper detail... would take several pages...

But, if wax allows the plane to go faster... go for it!

 

On the other hand... rough paint can be a lot like frost... frost can kill lift....   so... if you need a good reason to get new paint...

PP thoughts only, not an aerodynamicist...

Best regards,

-a-