M20J Speed Improvement?

[Steve W]

3 hours ago, mooneyflyfast said:

I'm flying from San Antonio to Sana Fe next week--520 n.m.--a fairly long trip for me.  At 155 knots I would save 7 minutes over the time it will take at my usual speed of 150 kts.  I would like my J to be faster but it is of little practical importance (and no one would believe me anyway).

If you were flying the other way it would be downhill and you could go faster.

[Dan208]

On 1/23/2018 at 10:39 PM, Raptor05121 said:

How are you getting 145KTAS out of an Archer? That's the same speed as my Mooney, same engine, I've got constant speed, lighter, smaller frontal area, and retractable gear. The 180hp Cherokees' I've flown will barely crack 120, on a good day

The Cherokee that I did my flight training in was painfully slow .  I never wanted anything to do with a brand P after that 25 hour treat.

 

[David Lloyd]

Forty years ago I flew our Cherokee to New Mexico to visit the in-laws.  Got home, slammed the door, sold it and bought a Mooney.

[INA201]

9 hours ago, David Lloyd said:

Forty years ago I flew our Cherokee to New Mexico to visit the in-laws.  Got home, slammed the door, sold it and bought a Mooney.

I flew an archer for four years and thought it was great!  I was just a 40 year old kid and didn’t know any better. Now I’m fully grown and mature adult at 50 and own a Mooney. Go figure! 

There are so many parameters to getting those last few knots.  Forgive me but I’ll list what I’ve done for posterity in the last four years.  I’m not gonna spend a ton extra on speed improvements.  Most of this stuff is coordinated with maintenance work and relatively cheap to do in aviation terms. 

1.  1978J with 900 hours on the engine with high 70s compression.  I don’t have a step or a belly beacon(came this way).

2.  Switched the Bracket air filter to a Donaldson and definitely increased MP by close to an inch in cruise. You can search Donaldson in forums and see that folks see similar results over the Bracket.

3. Detailed the plane mostly for aesthetics and to maintain the paint but I hear it helps.

4. Moved the big ole temperature probe off the top of the cowl and into a side vent cutout.

5. All the rigging is fairly straight except my cowl flaps are rigged to 3/4” when closed. I could probably close them a little more while still maintaining CHTs below 380. My ball is off center by about 1/4 of the ball so getting that checked while in annual now. 

6.  Just now getting the ram air door stc to disable it and will fiberglass it over and smooth it out at some point.

7. I bought new Comant antennas and removed the reverse sevens.(may not provide less resistance but in theory should)

8.  Put the Gee Bee silicone baffles as my old ones were shot. Did it under IA supervision and is relatively easy if you are handy.

9. Entire fuel system redone other than the fuel servo.

10.  New ignition wires, Tempest plugs to replace Champion, and it was time for the mag rebuild too.

11. Exhaust and intake system checked with exhaust being rebuilt in a couple of places to tighten it up. Intake had a couple of small leaks that were corrected and fully tightened up too.

12.  All old antennas that were still hanging out were removed notably the ADF, old LORAN etc. 

13. Getting prop balanced but not sure if that qualifies as a speed improvement but maybe 1/4 knot. 

14.  I’m in annual now and on full run up I’m only getting 2650 RPM so may be a 1/2 knot+ there.

Last 4 way test I did was at 2600RPM, full throttle, 6500 feet, no turbulence, 100 ROP, I was at 156 knots.

The only things I’ve done since the last test will be prop balance, and RPM up from 2650 if they can do it.  I’ll test again at some point and see.  

Some things I didn’t do that some people have done and I probably won’t do.

1. Enclose com antennas into the wingtips.

2.  Replace the wire VOR/ILS antennae with the blade type streamlined antennas that the newer Mooney’s come with.

3. Port Polish and flow balance the engine which I’m frankly unclear about.

4. Smoothing the leading edges of the wing to make a “perfect,” more or less leading edge.

5.  Power Flow exhaust

6.  Electronic Ignition

7. One piece belly

8. I’m  Probably missing one or two

The quest for more speed can be never ending but it’s all in fun!  I bet one of the engineers here can calculate the efficiency improvement at say 135knots when you’ve increased your top speed by 5 knots or so.  That may be the hidden gem in all this improvement stuff.

Long post, you know, sometimes we get excited.     

 

 

[Guest]

Owned 2 different E models, now own a Comanche, can’t see going back.  Got to run my old E model today, too noisy and too cramped inside, but it does have the most comfortable seats I’ve ever sat in.

Clarence

[Oldguy]

17 hours ago, INA201 said:

5. All the rigging is fairly straight except my cowl flaps are rigged to 3/4” when closed. I could probably close them a little more while still maintaining CHTs below 380.

Surprisingly, in Bob Kromer's presentation at one of the Mooney Summits, he said your 3/4" is good for the J model. According to him, in their flight testing, if the cowl flaps were closed too tightly, the air being pushed into the cowl would reverse and flow back out the front increasing the temps and reducing speed. My J has about the same opening as yours, when they are closed, and I typically run >360dF for my hottest CHT.

[OR75]

anyone on here can report on installing an IO-390-A3A6 ?

My overhaul is approaching .... currently have an IO-360-A3B6D ....

considering IO-360-A3B6 or the IO-390-A3A6   (i already have the right Hartzell prop for the IO-390 STC) 

They are about the same price and the same miscellaneous issues will come up (hose lengths , brackets , governor, ...) 

[wcb]

10 extra HP with the IO-390!  What if you did a port and polish on the cylinders also?  I understand the port and polish will get you about 20 hp.  So, if my math is right 10 + 20 would give you 30 more HP (nothing to sneeze at).  The question is for every percentage of increase in HP how much more KT can you gain?

[jaylw314]

9 minutes ago, wcb said:

10 extra HP with the IO-390!  What if you did a port and polish on the cylinders also?  I understand the port and polish will get you about 20 hp.  So, if my math is right 10 + 20 would give you 30 more HP (nothing to sneeze at).  The question is for every percentage of increase in HP how much more KT can you gain?

And how many fewer hours will your cylinders survive? 

IIRC, your airspeed varies to the square root of power.  so increasing the power by a factor of 1.15 will give you an increase of airspeed by 1.07.  Assuming you get that proportional increase in power at cruise speed (probably not a good assumption), that's a difference from 150 KIAS to 160 KIAS.

Edited June 19, 2019 by jaylw314

[wcb]

2 minutes ago, jaylw314 said:

And how many fewer hours will your cylinders survive? 

Have never looked into does port and polish decrease cylinder life.  Does anyone have the facts?

[jaylw314]

3 minutes ago, wcb said:

Have never looked into does port and polish decrease cylinder life.  Does anyone have the facts?

not other than the fact you're producing more HP and higher ICP than originally intended.

[Hank]

7 minutes ago, jaylw314 said:

not other than the fact you're producing more HP and higher ICP than originally intended.

Keep temps under control, shouldn't be a problem. Right? CHT < 380?

[KSMooniac]

Consensus from years ago seemed to be that the juice isn't worth the squeeze for the 390 conversion. If you've already got the prop maybe it isn't awful. Go price a replacement 390 cylinder before you decide.

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[OR75]

1 hour ago, KSMooniac said:

Consensus from years ago seemed to be that the juice isn't worth the squeeze for the 390 conversion. If you've already got the prop maybe it isn't awful. Go price a replacement 390 cylinder before you decide.

Sent from my LG-US996 using Tapatalk
 

$1850 vs $1300 

[KSMooniac]

Wow, if that's real that is a substantial change from a few years ago... $4000 each vs $2100.

 

Maybe the CMI PMA jugs entering the market have helped us?

 

Edit: airpower is showing $1587 for CMI & $1986 for Lycoming IO-360 wide deck/angle valve jugs.

 

Spruce shows no stock for 390 jugs, and $2143 for 360 Lycoming jugs in stock/drop ship.

 

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[OR75]

1 minute ago, KSMooniac said:

Wow, if that's real that is a substantial change from a few years ago... $4000 each vs $2100.

Maybe the CMI PMA jugs entering the market have helped us?

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Honestly, the biggest change vs. when the STC was introduced is that you don't need to go through a Lyc. service center.

cost of the Lyc. overhauled engine is now very close to the IO-360

used in the SR-20 helped

I am still running the numbers ... including weight ... Hartzell prop is 10 lbs heavier than the stock McCauley C212 prop but i compensated with installing a lighter starter (Sky-tec) - 10 lbs lighter than the stock starter 

 

 

[KSMooniac]

I went the other direction with my MT prop...12 lbs lighter than stock McCauley. I won't intentionally buy any Hartzell due to their propensity to issue AD's when they need a sales boost. I still plan to add a TN kit one of these years too and think that will suit me more than the 390+Hartzell.

 

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[wcb]

7 minutes ago, KSMooniac said:

I went the other direction with my MT prop...12 lbs lighter than stock McCauley. I won't intentionally buy any Hartzell due to their propensity to issue AD's when they need a sales boost. I still plan to add a TN kit one of these years too and think that will suit me more than the 390+Hartzell.

 

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Love my TN and glad I did not have to pay to add it after the fact.  How much are you thinking it is going to cost to add?

[KSMooniac]

Love my TN and glad I did not have to pay to add it after the fact.  How much are you thinking it is going to cost to add?

Hard to answer! Essentially zero after a lot of work on my part...Buying and parting a salvage plane with that kit. I plan to build an engine mock up (with un-airworthy pieces) and assemble the kit first to double-check everything, then get anything overhauled if needed, and finally install on my plane.

I didn't, and wouldn't, buy the kit at the last retail price of ~34 AMU. Can't buy a new one today anyway.

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[carusoam]

Check to see if Doc John still has his spare TN for his M20F... if interested...

10 extra hp at sea level is nice for shortening the T/O roll... and initial climb rate...

How well does the extra 10hp of the IO390 last as altitude increases?

Data might be found in the engine operating manual...

Best regards,

-a-

[jetdriven]

It’s actually only 7.5 horse power. Because the engine is limited to 200 horsepower after five minutes. Then as you climb your 7.5 hp becomes five then it becomes two. The most money ever spent for the smallest gain

[OR75]

6 hours ago, jetdriven said:

It’s actually only 7.5 horse power. Because the engine is limited to 200 horsepower after five minutes. Then as you climb your 7.5 hp becomes five then it becomes two. The most money ever spent for the smallest gain

Except costs seem to be very similar 

[Andy95W]

6 hours ago, jetdriven said:

It’s actually only 7.5 horse power. Because the engine is limited to 200 horsepower after five minutes. Then as you climb your 7.5 hp becomes five then it becomes two. The most money ever spent for the smallest gain

It sure seems like the best option is a factory IO-360 A3B6 with roller tappets and a PowerFlow exhaust.  IIRC, this was echoed in a MAPA Log article a few years back when the IO-390 first came out.

 

24 minutes ago, OR75 said:

Except costs seem to be very similar 

The cost savings kick in every time you need cylinder work done.

[INA201]

My thought on speed is practical in nature. I bought a Mooney for its history, looks, efficiency, cool factor, safety, and of course speed(ego maybe).  My philosophy is to restore it as close to the way Mooney designed it to be without breaking the bank while modernizing the electronic side.  I’m satisfied with 156knots but in the back of my mind there is always a desire to go for more. That being said if you need a new engine why not add the port and polishing to it along with balancing it all out.  Also, if I had needed a total new exhaust instead of a $750 repair I probably would go for the nicely designed power flow for a little more. If it was time for a totally new magneto it may be worth considering Electronic Ignition to bring digital timing advance into play.  If you like tinkering and a little extra work add a turbo for fun and let us know.  A lot of the real tinkerer types don’t always show up on forums so who knows what other folks have done to speed up.  There is always more but we’ve already got an A on the test by buying a Mooney.  Studying an extra ?? hours to make an A+, who knows?  

[jetdriven]

58 minutes ago, OR75 said:

Except costs seem to be very similar 

How much more is the 390 vs the 360 and how much is that prop that has to be used with it?

a few years ago we looked at it. The prop was 10k and the engine was also around 10k more. No overhauled ones were available. Rebuilt was but it was expensive. 

Edited June 20, 2019 by jetdriven