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M20J Speed Mods?

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What speed mods did your M20J come with, what have you added, and what do you think the value (speed, efficiency, and speed to cost ratio) of each is? Perhaps a list of mods from most favorable to least?

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Added Power Flow Exhaust system. This has added 3 to 4 knots at 7000 using full manifold pressure and 2400 RPM.

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What speed mods did your M20J come with, what have you added, and what do you think the value (speed, efficiency, and speed to cost ratio) of each is? Perhaps a list of mods from most favorable to least?
Are you trying to catch me?
carusoam likes this

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Gami injectors......allowed operations closer to the red box when low such as 4k feet. Typically can now run 5 degrees lop down low and keep Alm cylinders below 360. Increase of 5kts by not having to baby the richest cylinder.

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And here I thought the J came with all speed mods from the factory . . . All that's left is to keep the throttle forward, climb high, push prop further forward, and maybe fly some amount ROP to go faster than the LOPers.

 

But what do I know? I have a C with several 201-style mods.

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I haven't altered any exteranl features of my bird, but I guess it came with one speed mod when I bought it: a 3-bladed prop. And according to everyone's opinion, this modifies the speed downward! Since I haven't flown a 2-bladed J I can't say, but I still seem to do all right.

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I have about every mod you can think of that came with my '78 J.  I have no idea how much they increase the speed because they were there when I got it, but I can tell you that at about 8000' the Ram air on the Lopresti cowling gives me about a 5kt boost.  5kt is not worth what those things cost if you ask me, but since I have it, I like it.

 

http://flightaware.com/live/flight/N201AT/history/20130827/1501Z/KMEM/KBHM

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I think that weight reduction, antenna removal, rearward CG, slick paint, and good rigging will get you way farther in an early 201 than all of the late model M20J aerodynamic mods combined. Just my .02.

Jim

Exactly. Optimize what Al Mooney gave you, then start bolting on stuff. We sped ours up about 4 knots in cruise just correcting what was wrong, and removing unneeded antennas.

bluehighwayflyer and PTK like this

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I have about every mod you can think of that came with my '78 J.  I have no idea how much they increase the speed because they were there when I got it, but I can tell you that at about 8000' the Ram air on the Lopresti cowling gives me about a 5kt boost.  5kt is not worth what those things cost if you ask me, but since I have it, I like it.

 

http://flightaware.com/live/flight/N201AT/history/20130827/1501Z/KMEM/KBHM

 

faster or not, that lopresti cowling is damn cool.

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Speed improvements are mostly significant on long flights

On a 200nm a 5kts difference translate to a 2 minutes difference.

However on 1000nm a 5kts difference translate to 12 minutes difference.

But if you need to stop for fuel the difference can be more than an hour.

 

I found that adding extra fuel allows me to run at higher power thus higher speed non-stop thus shorter time, vs stoping for refueling or running at low speed to increase range. If you encounter headwinds and have to land for refuel your speed mod investment goes down the drain. For a speed mod to be significant the plane has to be run at high power setting, thus more fuel. At low power setting (less drag) speed mods are insignificant.  

 

I measure speed in total trip time vs true air speed.

Time for ground preparation for a flight should be part of the total trip time.

By coincidence my front hangar neighbor was headed to KORL on his Citation I jet at the same time I has headed there too. By the time I started taxing out he and his copilot were still doing checks on the plane in the hangar. I arrived at KORL and pickup the crew car to drop my wife at my son home. By the time I was leaving the gate I saw my friend taxing in his jet. When I drove back to the airport he was still loading the rental car. 

 

The same can be said when comparing an airline flight vs your Mooney. I even include the driving and parking in the total trip time. To me is the total trip time what matters.

 

José 

OR75, carusoam, BigTex and 3 others like this

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José,

Are you responsible for the graph in the MAPA Log?

The one that shows the Monroy tanks that allow skipping the time on the ground for refueling (descend, land, refuel, T/O, climb).

The extended tanks often make an excellent speed mod!

Best regards,

-a-

petegaz40 likes this

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The extended tanks often make an excellent speed mod!

They're not a speed mod. In fact they make you go slower than faster. However, it's the time and/or cost to destination that is reduced and absolutely worth it.

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Over the years in two Mooneys I think I have tried just about every speed mod available, including some one off 337 stuff. Currently my M 20J has LoPresti cowl, a Powerflow exhaust system, a one piece belly pan, very smooth new paint, a two bladed Top Prop, and all sorts of fairings. The rigging is perfect (hands off in cruise), done by LASAR, flow matched cylinders, prop balanced to the limits of the balancing machine, but many too many antennas. For my 261 conversion we buried most of the antennas, but now I have two external GPS antennas, the towel rack on the tail, a 406 ELT antenna, a ADS-B antenna, and a transponder antenna. And two comm antennas personally, I think these antennas nullify some of the speed mods. At 8000', ram air open, 2550 RPM, and a fuel flow of about 9.6 GPH , I true out at 160-163 KTAS . I can eke out a couple more knots running ROP, but I hate paying for the extra fuel. I spend a fair amount of time looking a predicted winds aloft to maximize tail winds, and minimize head winds, and even consider alternate routes. By the way, I keep lots if survival gear in the baggage department to keep an aft CG. I also play the fuel flow/ power/ speed game to avoid unnecessary fuel stops on long flights, but I never land with less than one and a half hours (14 gal) usable in the tanks. My 261 was better for really long trips (115 gallons), but that required flying in the mid flight levels, sucking oxygen, and generally freezing. The 201 is fine for 500 - 700 mile trips, and I normally fly at non- oxygen altitudes. Any Mooney is a good aircraft, and faster than most.

bluehighwayflyer likes this

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Bennett, could you please talk about the value of each mod you've tried and the cost to speed payoffs? Can you make a list in order of preference that you would add those to a factory stock 201?

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José,

Are you responsible for the graph in the MAPA Log?

The one that shows the Monroy tanks that allow skipping the time on the ground for refueling (descend, land, refuel, T/O, climb).

The extended tanks often make an excellent speed mod!

Best regards,

-a-

Yes. The graph is mostly applicable to the M20M owners that use their plane for long distance flights (1,000nm). But because the plane burn so much fuel they needed to slow down to make the range. Aircraft manufacturers usually advertise top speed and top range, but you cannot get both simultaneously. This finding motivated many M20M owners to install the long range tanks. My motivation was to skip the fuel stop and Customs on my way to San Juan. No Missile conversion or speed mod would have got me there quicker.

 

José.  

carusoam likes this

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Bennett, could you please talk about the value of each mod you've tried and the cost to speed payoffs? Can you make a list in order of preference that you would add those to a factory stock 201?

 

Increasing speed comes from three major areas: 1. Increasing power, 2. Reducing drag, 3. Reducing weight

 

The common mods for increasing power for a stock 201 would be 1. The PowerFlow exhaust System, 2. Using the LoPresti cowl version of Ram Air, 3. the "Scimitar" Top Prop for more effective power transfer efficiency, and  4. Turbonormalizing, or a straight turbo conversion.

 

Remember that you have to add a great deal of power to equal the speed differences brought about by a reduction in drag. The PowerFlow exhaust system seems to live up to its hype, with some increase in power,hence climb rate and level speed. I cannot quantify this, as I have always batched my mods, and installed several at once. One thing to consider: At each annual the PowerFlow exhaust system has to be serviced, and this has averaged about $500 per year for me.  The LoPresti cowl is a piece of art - well built, at least in the early versions. I will come back to this under drag reduction, but the Ram Air function is very effective in helping maintain power with increasing altitude. I gain about 1 to 1.25" MP around 8,000' - 10,000', which is a significant percentage gain in power. I really like the Hartzell two bladed Top Prop. For another aircraft I owned I experimented with several props; two and three bladed, and the modern two balded prop appears to be more efficient at transmitting power.  I have no experience with turbonormalizing for a 201, but I can tell you, that below about 8,000' my 261 conversion (turbo, with a critical altitude of 24,000') was no faster than my 201.  Part of this because the 261 was heavier, and partially because the optional McCalley  prop I was running was optimized for the flight levels, and not very effective until at least the mid teens.

 

Drag reduction: Most speed mods fall into this area. In my opinion, the the biggest "bangs for the buck" are 1. Remove the fixed step.  On the 261, this single mod, done separately from the others, resulted in a solid 2 knots increase in KTAS. My 201 still has the step, but this will be removed soon. 2. Have the aircraft rigged by one of the MSC experts - LASAR, Top Gun, Maxwell and a few others. Just using the travelling boards is not enough, in my opinion. The aircraft has to be flown, and ever finer adjustments made. The ailerons are especially sensitive, and above all, don't let the aircraft fly in a slip or skid while in level flight. 3. Keep useful "stuff" in the baggage compartment to keep an aft CG; especially when flying alone, or with a co-pilot. 4. the LoPresti cowl will increase your speed, but at quite an expense. There are many parts to the LoPresiti cowl - new overlapping gear doors, with a fairing behind, a windshield fairing, and of course, optimized air intakes and exhausts.  If Mooney were ever to build new 201s, this should be part of that program.  5. The one piece belly pan is not so much useful as drag reduction as it is a place to move a few antennas inside.  Some antennas seem to function effectively when inside a fiberglass belly pan, while others, like stormscopes (at least in my experience), do not. 6. Reduce the number of external antennas, if possible. The VOR antennas (soon to be obsolete), whether the towel bar, or blade type, can be moved into fiberglass wingtips. I did this on the 261, and the VORs worked just fine.  I haven't done this on my 201, as I believe that VORs may well be gone in the next five years, and there is a good deal of expense in running shielded wires through the wings, and modifying the wingtips to hold the antennas.  What I want (there is no STC for this that I know of), would be to build a "well" or compartment of sorts directly above the hat shelf with a clear plastic top to house the "external" GPS, XM, and ELT antennas. These antennas, and the Comm antennas really cause a good deal of drag. 6. The Top Prop two bladed prop has less drag than the three bladed Top Prop (and some other three bladed props). 7. Keep the aircraft polished, and remove bugs from the leading edges of the wings, and from the flush riveted areas of the wings to maintain laminar flow for as long as possible.  Also, keep the belly clean and polished. Surprisingly effective in reducing drag.

 

Weight reduction: A balancing act. Putting stuff in the baggage compartment moves the CG aft, which is good as a drag reducing measure, but the added weight reduces performance - speed.  Likewise, full fuel adds weight, but increases range, avoiding a fuel stop.  As Jose points out, avoiding a fuel stop can result in a significant reduction in block time. And you don't have to add long range tacks for flights out to 700 miles or so.  I fly from San Carlos to Scottsdale, Arizona without an interim fuel stop when I run LOP, giving up a few KTAS, but being able to land with my personal landing fuel minimum of one and a half hours usable fuel in the tanks. When I have flown this route Balls to the Wall (not a sexist remark - balls are the tops of the throttle/mixture/prop quadrant levers for those who have them), I have to make a fuel stop, and while my True airspeed increases by up to 5 or 6 KTAS, the fuel stop kills block time.  

 

And while we are talking about block times, having speed brakes allow you to maintain high speeds closer to the destination airport.  I don't see them as a crutch (I guess I'm a wuss pilot), but as an effective tool to dump speed before setting up for landing.  Yesterday I had strong tailwinds aloft down to about 1000', and then a moderate quartering headwind at the runway. I rode those tailwinds down from altitude at ground speeds up to about 190 Knots to within about 6 miles to the runway, given a straight in clearance, then popped the speed brakes, slowed to gear speed, dropped the rollers, and then full flaps, and crossed the runway threshold at 70 Knots, and touched down at 65 Knots. 

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Excellent analysis, bennett. 

a couple comments. For those that dont have the fiberglass wingtips, the VOR antenna situation becomes more difficult. We left the cat whiskers because it was going to cost us two grand to install the blade antennas, and the fiberglass wingtip conversion is perhaps 5 or 6 grand. So we suffer with the cat whiskers.

 

I havent heard any quantifiable data that points to an increase in airspeed with the Powerflow exhaust. I offered to let them sponsor me in a couple of the air races with a discounted system, and they refused. I thought their name on the side of a 200 MPH  M20J would be good advertising.

 

I dont have speed brakes but I can slow down an M20J from 190 knots in about 2-3 miles given a level segment.  Just get down to 1000 AGL, set power to 17", gear and full flaps at the limit. As the airspeed srops below ~110 MPH, reduce power to 1800 RPM.  Holding it at the same altitude during this time is key.  It works.

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Very nice write-up Bennett, with just a couple of minor quibbles.
 
All 201 cowlings are LoPresti designs. The non OEM ones are expensive and of questionable quality as you point out, and you're lucky to have an early one. Per what Roy LoPresti told me, the only real speed improvement was the positioning, size and shape of the air intakes in the nose.
 
All data and reports I've seen claim negligible speed improvements for the PowerFlo hooked to a 201, especially the newer ones. Also model year of the 201 is important when discussing speed mods, since Mooney made incremental improvements as the 201 matured.
 
A friend with a 231 took detailed speed notes years ago, before and after removing his welded on step. He said the increase was 0.5 kts, under the best of circumstances, so I can't imagine a 2 kt increase. His wife also never forgave him! :o
 
Byron.....how the heck do you slow down in level cruise from 190 knots to gear and flap deployment speed in 2-3 miles? Come to think of it, how did you get to 190 knots to begin with?
 
Finally...what is Mike201er up to with these demanding requests? :P

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I mentioned strong tailwinds at altitude, so ground speed yesterday (not TAS) was 190 Kts. The class Bravo rings around San Francisco airport require dropping below 8000' then 6000' and then 4000' VFR. I typically descend at about 450' per minute after scooting under the 8000' ring which gets me to about 3500' about 10 miles from the airport. We normally get a straight in to Rwy 30, so I have plenty if time to bleed off airspeed to drop the gear. Yesterday the tail winds continued (though diminishing) to about 1000'. TPA at KSQL. Is 800' with the airport at just above sea level. With the tailwind I was getting to my normal descent point for a straight in at 3 miles from the runway faster than normal, and a steeper descent was prudent, hence the deployment of speed brakes. Could I have done different things? Sure, but speed brakes made it real easy. Just another tool to use when it makes sense to do so Clever point about all 201 cowls being LoPresti cowls. I do like the ram air system on the aftermarket system, and the workmanship on mine is just fine. I recall that Paul at LASAR tested the PowerFlow exhaust system on a 201, and I called him this morning to ask if he still had the data. He said he didn't, but he said that both climb and level speed were improved. When Mod Works cut off my step in the 261, we tested the airplane before and after via averaging the four cardinal directions, and saw a two knot improvement in speed after removing the step. Of course, even at the same altitude, weather conditions could have been different. I sometimes slip off the step, so it won't be missed when I have it removed on the 201 It is hard to gain any significant speed improvements on the J, but the cumulative effects of all the mods I have give me a reasonable cruising speed, and I am happy with the mods.

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Byron.....how the heck do you slow down in level cruise from 190 knots to gear and flap deployment speed in 2-3 miles? Come to think of it, how did you get to 190 knots to begin with?

That the typical descent profile for me, full throttle, 15 LOP in cruise (usually 9 GPH or so), and keep that power setting and FF all the way down, 180-200 MPH IAS, 750-1000 FPM descent until 3 miles from airport, usually gives a 175 knot groundspeed, sometimes up to 200 knots.  For a straight in, arrive at pattern altitude 6 miles from the runway.  For a midfield crosswind entry, 2-3 miles from airport center.  The key is a 2-3 mile level segment.  Level off, set the power to 17", and wait a minute, at 153 MPH gear down, you only have to lose 40-50 MPH IAS to get that. If you get short on distance, pull it up 200' to get the gear speed.  After the gear is down, it really slows down in a hurry.  Full flaps at the white arc. Next time flying, give it a shot.  That descent profile (along with the target EGT 123 KIAS climb) makes such an impact on the block time, you can often show a block speed of 150 knots, or you can fly to a destination 150 NM away in one hour.   Technique is a good speed mod as well :)

 

this is 188 KTAS or so. GS was 199 knots

post-7887-0-36209000-1377726443_thumb.jp

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