To Turbo or Not- an numbers Question

[Jaybird180]

I'm comparing some figures for my favorite plane to someday be in my hangar (guess which plane). Previously, I was convinced that normally aspirated was the way to go, but now I'm less convinced.

I recently read about the merits of getting there faster. So I started running some numbers with a friend who was handy with Excel and based on the numbers, began to rationalize that I could live with the added overhaul costs by gaining some fuel and time savings with the turbo model.

I decided to draw out my own spreadsheet and do a more in-depth analysis this time (It's funny how one can rationalize anything).

Green are figures in favor of turbo (K) and red for non-turbo (J), but I wish I had better data for maintenance costs...

 

[tonycondon]

how often are you flying 500 mile trips and how much is 20 minutes worth to you?

 

[Jaybird180]

I'd probably do 500nm once per quarter. But I then need a return trip, so double those costs.

And it's 24 minutes saved (LOL)...

 

[tonycondon]

well i guess if 3 hours a year is worth the increased costs then go for it!

 

[Clark1961]

Speaking as the owner of a turbo'd aircraft, I've gotta say that the only reasons to turbo are for long (high) trips and high DA operations.

From a practical point of view, going high means using O2 so plan on putting up with that annoyance (not just wearing a cannula or mask, but keeping the bottle full).

High DA ops, well, now that's where the turbo is very nice. If ease of operations out of high, hot runways is on your list then the turbo is cheap.

 

[poadeleted20]

If you aren't going west of Denver, you probably won't get much added value out of a turbocharger.

 

[Trapper John]

I'd probably do 500nm once per quarter. But I then need a return trip, so double those costs.

And it's 24 minutes saved (LOL)...

But you don't magically end up at the higher altitude where the 231 trues out faster than the 201. Since we're talking about small amounts of time, we should be looking at time to climb to that altitude, since cruise-climb is slower than the ultimate cruising speed, right? And what do you do if the trip is east-to-west where the higher you go, the greater the headwind you might get?

 

[ebetancourt]

Having done a 570NM trip (one way) in a K (252) weekly for about three years and less often for another 6 or so, I have to say no other plane would have done it as well, and yes, it was more expensive and the K model engine is among the most expensive to overhaul. Think 40K+ when the dust settles!!

Oxygen was not a problem for me, I simply got two bottles of ABO from the local welding shop (Had to wait for the ABO but the cost was about the same). Getting the acft bottle tested and/or replaced was another cost but not that much in the overall scheme of things.

Being able to go above a lot of weather allowed me to make the trip on days when I could not have done it in a lesser aircraft. And the speed difference is real. My trips were directly west or directly east. Best time ever was 2+13 I think. East bound was the going home leg and counted twice as much The west bound leg was not noticeably slower than it would have been in a J BTW, just used a little more fuel. Cruise climb yielded about 700 FPM through about 12K then down to about 500 FPM in the Class A. But cruise climb at that altitude was about the J cruise. And descending was a lot quicker than cruise (top of the green) and made up for a lot of the slower climb.

All that said, I don't think I would do it for once a quarter trips.

Ernie

 

[taters]

The turbos are about 5 grand more the NA at overhaul, a top OH is not that uncommon at all, but the 1-2 GPH you might save if you fly enough can make a dent in this. I think trying to justify things in financial terms goes against the very spirit of aviation though...Turbo it if you can!

 

[Jaybird180]

If you aren't going west of Denver, you probably won't get much added value out of a turbocharger.

Is that Colorado or Pennsylvania(being a smarta$$)

 

[Jaybird180]

The turbos are about 5 grand more the NA at overhaul, a top OH is not that uncommon at all, but the 1-2 GPH you might save if you fly enough can make a dent in this. I think trying to justify things in financial terms goes against the very spirit of aviation though...Turbo it if you can!

Is that all? I'd figured $15k diff @ 2000TBO vs 1800TBO

 

[poadeleted20]

Is that Colorado or Pennsylvania(being a smarta$$)

Didn't even know there was a Denver PA, but there it is, right there in Lancaster County with all the Amish. So, I'll have to amend that to "west of Denver CO."

 

[poadeleted20]

Is that all? I'd figured $15k diff @ 2000TBO vs 1800TBO

Book TBO may not be that much less on a turbo vs non-turbo model of the same engine, but turbos are notorious for not making TBO, while engines like the IO-540 in the new 182's are legendary for their longevity.

 

[Jaybird180]

Having done a 570NM trip (one way) in a K (252) weekly for about three years and less often for another 6 or so, I have to say no other plane would have done it as well, and yes, it was more expensive and the K model engine is among the most expensive to overhaul. Think 40K+ when the dust settles!!

Oxygen was not a problem for me, I simply got two bottles of ABO from the local welding shop (Had to wait for the ABO but the cost was about the same). Getting the acft bottle tested and/or replaced was another cost but not that much in the overall scheme of things.

Being able to go above a lot of weather allowed me to make the trip on days when I could not have done it in a lesser aircraft. And the speed difference is real. My trips were directly west or directly east. Best time ever was 2+13 I think. East bound was the going home leg and counted twice as much The west bound leg was not noticeably slower than it would have been in a J BTW, just used a little more fuel. Cruise climb yielded about 700 FPM through about 12K then down to about 500 FPM in the Class A. But cruise climb at that altitude was about the J cruise. And descending was a lot quicker than cruise (top of the green) and made up for a lot of the slower climb.

All that said, I don't think I would do it for once a quarter trips.

Ernie

Thank you Ernie for the data. How much is that +?

BTW, were you selling a 252 awhile back? I saw a guy Ernie on one of the Mooney boards discussing his pricing thought process. If that was you, did you get it sold? Have you ever owned a J?...lastly, I'm having a tough time getting empty weights for J's and K's do you have that data or know where I can look it up myself, I didn't find it in the TCDS.

 

[Jaybird180]

Book TBO may not be that much less on a turbo vs non-turbo model of the same engine, but turbos are notorious for not making TBO, while engines like the IO-540 in the new 182's are legendary for their longevity.

I'm considering that too, but from what I'm reading it seems that the difference is pilot technique. Mooney also did some things different in the 252 that resolved some longevity issues that the 231 had in making TBO.

I'm also heard a peep that the J had issues with exhaust that was just as costly as a turbocharger OH. But again, scarce data to confirm...it may even up the score a little.

Maybe Lance will chime in - he's got a J model.

 

[Fearless Tower]

Is that all? I'd figured $15k diff @ 2000TBO vs 1800TBO

There is a lot of variation - it depends on the model. There may be some that are only 5K more for the turbo, but I'd say 10-15 is a bit more realistic, could be even more. Best to research the model you are interested in. Also, TBOs will vary. There are non-turbo'd/non-fuel injected engines that have recommended TBO's less than 2000.

 

[taters]

Is that all? I'd figured $15k diff @ 2000TBO vs 1800TBO

Was for me on the last 2 overhauls I managed . 5k-7k over what our NA plane cost at overhaul time, you can bet on 38-40k all day long. We had to replace about half of the cylinders halfway to TBO, they were partially covered by warranty.

 

[Ted]

Given your trips, turbos will probably add more headaches and cost than benefit. 500 nm only 3 times a year really aren't enough to justify a turbo, unless you live in Colorado.

In my case, I really wish I had turbos. For the long trips I make, the ability to make altitude more easily would be a huge advantage. But my average trip is something on the order of 600-800 nm every few weeks. I'd add turbos if there was a way to do it easily and affordably.

There is a huge variability within turbo engines, and whether or not they need a top overhaul or not make TBO will be completely based upon how you treat the engine. They certainly are less forgiving to poor treatment. I know some people who are way past TBO on their turbo engines quite happily, and others who fought bitterly to make TBO. There is no question when you look at operating processes as to why one had one experience vs. the other.

 

[taters]

Given your trips, turbos will probably add more headaches and cost than benefit. 500 nm only 3 times a year really aren't enough to justify a turbo, unless you live in Colorado.

In my case, I really wish I had turbos. For the long trips I make, the ability to make altitude more easily would be a huge advantage. But my average trip is something on the order of 600-800 nm every few weeks. I'd add turbos if there was a way to do it easily and affordably.

There is a huge variability within turbo engines, and whether or not they need a top overhaul or not make TBO will be completely based upon how you treat the engine. They certainly are less forgiving to poor treatment. I know some people who are way past TBO on their turbo engines quite happily, and others who fought bitterly to make TBO. There is no question when you look at operating processes as to why one had one experience vs. the other.

I would say there is a certain luck component to it as well. Ive been on the wrong end of bad metallurgy and a FADEC that cost me cylinders. The verifiable data that I ran the engine per SOP saved my bacon for warranty purposes.

 

[denverpilot]

Given your trips, turbos will probably add more headaches and cost than benefit. 500 nm only 3 times a year really aren't enough to justify a turbo, unless you live in Colorado.

Heh... I live in Colorado and fly West, and even I can't justify a turbo! Not on a budget, anyway.

CAP flies 182's here due to the altitude, but also doesn't have all that many turbos... the T182T is in the shop more than I'd like if I owned it, usually not for turbo-related issues, mostly for starter-related ones, a G1000 connector issue, and various other "fidgety" things. It also had some turbo over-boost issues early-on that the shop straightened out, I believe. Most of the rest of their fleet of 182s are normally-aspirated here.

It can be challenging for three fat guys, survival gear, and enough fuel to do something useful, still to be under max-gross on those restart 182s with all their extra weight.

Restart Cessnas mimick the U.S. Population, and got heavier. Chubby birds. The G1000 T182T is a Turbo-Pig, kinda. Lot of extra weight on-board with the radios and other things they add under the standard CAP STC work, too.

 

[Dr. O]

We fly by the hour for fun and then we spend all our non flying days figuring how to get a faster plane so we can get there in less time and log fewer hours - huh?

denny-o

 

[Ted]

I would say there is a certain luck component to it as well. Ive been on the wrong end of bad metallurgy and a FADEC that cost me cylinders. The verifiable data that I ran the engine per SOP saved my bacon for warranty purposes.

Luck is as much a factor as it is with any engine. Bad metallurgy or bad cylinders can always be an issue. However most of the time I find people are typically running them wrong, and then wonder why they broke.

 

[wabower]

The local T-Aztecs seem to be much more problematic than my TSIO-520's. Is that universally true?

Given your trips, turbos will probably add more headaches and cost than benefit. 500 nm only 3 times a year really aren't enough to justify a turbo, unless you live in Colorado.

In my case, I really wish I had turbos. For the long trips I make, the ability to make altitude more easily would be a huge advantage. But my average trip is something on the order of 600-800 nm every few weeks. I'd add turbos if there was a way to do it easily and affordably.

There is a huge variability within turbo engines, and whether or not they need a top overhaul or not make TBO will be completely based upon how you treat the engine. They certainly are less forgiving to poor treatment. I know some people who are way past TBO on their turbo engines quite happily, and others who fought bitterly to make TBO. There is no question when you look at operating processes as to why one had one experience vs. the other.

 

[Ted]

The local T-Aztecs seem to be much more problematic than my TSIO-520's. Is that universally true?

I don't know a ton about the turbo Aztecs, however I would expect them to have problems. The Aztec has horrendous cooling, and it is very difficult to keep the heads at a reasonable temperature for longevity. I don't think they did anything to improve it on the turbo Aztec.

I don't know which installations you work with for your TSIO-520s, but I know the IO-520s in the 310 cool immensely better than the IO-540s in the Aztec. If you look at the cowls, the 310 has a much better design for airflow, and the 520 heads look to have a good cooling fin design.

 

[Jaybird180]

Was for me on the last 2 overhauls I managed . 5k-7k over what our NA plane cost at overhaul time, you can bet on 38-40k all day long. We had to replace about half of the cylinders halfway to TBO, they were partially covered by warranty.

Did you mean 5-7k including the cylinders or 38-40k including?

 

[flyingcheesehead]

Didn't even know there was a Denver PA, but there it is, right there in Lancaster County with all the Amish. So, I'll have to amend that to "west of Denver CO."

I think PA names their cities and villages just to mess with people.

First, there's at least 5 city names which are duplicated (for example, there's a Hanover near Allentown, and another Hanover near York), and 2 names which appear on the map THREE times!

Then, there's the names that are duplicates of much more well-known places outside of PA: Denver, Indiana, California, you'll find 'em all in PA.

 

[Clark1961]

Ya'll understand there's also a Denver TX don't cha?

 

[gprellwitz]

Ya'll understand there's also a Denver TX don't cha?

Yabut, who cares?

 

[weilke]

I think PA names their cities and villages just to mess with people.
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Then, there's the names that are duplicates of much more well-known places outside of PA: Denver, Indiana, California, you'll find 'em all in PA.

Come to Maryland: Hollywood is just up the road from California and Pasadena is not far either :wink2: .

 

[flyingcheesehead]

There is a lot of variation - it depends on the model. There may be some that are only 5K more for the turbo, but I'd say 10-15 is a bit more realistic, could be even more. Best to research the model you are interested in. Also, TBOs will vary. There are non-turbo'd/non-fuel injected engines that have recommended TBO's less than 2000.

FWIW, AOPA Vref lists the overhaul cost for the J at $29,000 and for all the K's at $42,000, a $13,000 difference.

Also FWIW, the cost listed on Vref for the 182's O-470 when we got it done EXACTLY matched the price charged by the overhaul shop - Which is to say, it did NOT include any of the removal and reinstallation costs or any of the accessories. I'd say the OP's spreadsheet is probably pretty good with its $35K and $50K estimates for the total cost of the overhaul.

 

[flyingcheesehead]

Ya'll understand there's also a Denver TX don't cha?

There's a Paris, TX too. Must be some confused people there, threatening to kick someone's ass and then immediately surrender.

 

[flyingcheesehead]

I'm comparing some figures for my favorite plane to someday be in my hangar (guess which plane). Previously, I was convinced that normally aspirated was the way to go, but now I'm less convinced.

I recently read about the merits of getting there faster. So I started running some numbers with a friend who was handy with Excel and based on the numbers, began to rationalize that I could live with the added overhaul costs by gaining some fuel and time savings with the turbo model.

I decided to draw out my own spreadsheet and do a more in-depth analysis this time (It's funny how one can rationalize anything).

I never much cared for turbos on airplanes until I got a car with a turbo. I really like still having the power, without having to carry the weight of a bigger engine.

That got me looking at turbos on airplanes, too... But it really is mission-dependent. If you fly mostly short legs, the turbo won't get you anything but a bigger hole in the wallet.

I put together a spreadsheet more geared toward performance. It uses some assumed values, but at least based on reality, and it attempts to calculate time and fuel burn for climb, cruise, and descent for various cruising altitudes and various trip lengths. After playing with it for a while, on that particular aircraft type it looked like a good rule of thumb was that the fastest trip time would happen if you climbed 1,000 feet per 18nm of trip length, and the most efficient trip would be climbing 1,000 feet per 20nm of trip length.

So, anything under 160nm (8000 feet) you really wouldn't gain anything over the normally aspirated version of that airplane. Less than double that, it's a pretty marginal gain. So, to make the turbo worthwhile you'd have to be doing legs of well over 300nm on a regular basis.

On one hand, I currently do only a few 400nm+ trips per year in general. On the other hand, maybe if I had a turbo'd bird I'd do more. Only you can decide if it's really worthwhile.

 

[Ted]

I never much cared for turbos on airplanes until I got a car with a turbo. I really like still having the power, without having to carry the weight of a bigger engine.

That's not how turbos work on airplanes, though. On a turbo airplane, you're typically carrying around more weight to produce the same power (sometimes a bit more power). The difference is you can now produce that power up to a higher altitude.

Then you've got the Navajos, 340s, and P-Barons which do boost the engines enough to get extra power out of them, but even then, you're carrying around more weight to get more power. Turbos in cars are used to actually get a higher power density out of the engine. In airplanes that can be a motivating factor, but the true benefit is being able to make power at a higher altitude.

That got me looking at turbos on airplanes, too... But it really is mission-dependent. If you fly mostly short legs, the turbo won't get you anything but a bigger hole in the wallet.

Typically true, but also depends (see above). For example, a friend of mine upgraded from a Colemill 310 to a RAM T310R. Looking at his speeds, I think his new plane ends up getting about the same miles per gallon, and it probably costs about the same amount to maintain per mile (just going 25-40 kts faster than he was before). Per hour, yes, it's more money spent, but time is money for a number of people.

On one hand, I currently do only a few 400nm+ trips per year in general. On the other hand, maybe if I had a turbo'd bird I'd do more. Only you can decide if it's really worthwhile.

Agreed. However I find that most people who buy turbos really don't need the extra headaches for their mission profile.

 

[wabower]

More often than not those who care the most are motorists who need fuel between Lovington and Seagraves.

Yabut, who cares?

 

[Jaybird180]

...
I put together a spreadsheet more geared toward performance. It uses some assumed values, but at least based on reality, and it attempts to calculate time and fuel burn for climb, cruise, and descent for various cruising altitudes and various trip lengths. After playing with it for a while, on that particular aircraft type it looked like a good rule of thumb was that the fastest trip time would happen if you climbed 1,000 feet per 18nm of trip length, and the most efficient trip would be climbing 1,000 feet per 20nm of trip length.

So, anything under 160nm (8000 feet) you really wouldn't gain anything over the normally aspirated version of that airplane. Less than double that, it's a pretty marginal gain. So, to make the turbo worthwhile you'd have to be doing legs of well over 300nm on a regular basis.

On one hand, I currently do only a few 400nm+ trips per year in general. On the other hand, maybe if I had a turbo'd bird I'd do more. Only you can decide if it's really worthwhile.

Valuable Data sir.

That's not how turbos work on airplanes, though. On a turbo airplane, you're typically carrying around more weight to produce the same power (sometimes a bit more power). The difference is you can now produce that power up to a higher altitude.
...

Agreed. However I find that most people who buy turbos really don't need the extra headaches for their mission profile.

I believe what you're describing is turbo-normalizing. We're turbo-charging here for a 10HP increase and the ability to make rated power at altitude.

 

[COFlyBoy]

We fly by the hour for fun and then we spend all our non flying days figuring how to get a faster plane so we can get there in less time and log fewer hours - huh?

denny-o

Exactly!!! Do you fly for fun or do you fly to get somewhere fast?

If its for fun, why would you want to do any less?

I make at least 2 big trips (~1000 nm) a year at 130kts and a bunch of shorter ones and I've yet to really wish I could go faster. I have flown in my buddies 20J and from looking out the window you can't tell you're moving 35kts faster than my plane.

Not bagging on the Mooney its a great plane, but quibbling over speed only makes sense if you have a mission that requires more speed.

Edit: Oh and I do fly through the big hills in a NA bird. You get to shoot through passes and its very cool. I wouldn't trade it for messing with maintaining a turbo and filling an O2 bottle.

 

[flyingcheesehead]

That's not how turbos work on airplanes, though. On a turbo airplane, you're typically carrying around more weight to produce the same power (sometimes a bit more power). The difference is you can now produce that power up to a higher altitude.

I know, it's just that getting the turbo in the car and liking it is what made me get curious about turbos in airplanes. And since I like to go places, I think I like 'em in airplanes too.

Typically true, but also depends (see above). For example, a friend of mine upgraded from a Colemill 310 to a RAM T310R. Looking at his speeds, I think his new plane ends up getting about the same miles per gallon, and it probably costs about the same amount to maintain per mile (just going 25-40 kts faster than he was before). Per hour, yes, it's more money spent, but time is money for a number of people.

I'm not familiar with the differences - Is he getting higher speeds at the same altitudes, or is he going higher?

However I find that most people who buy turbos really don't need the extra headaches for their mission profile.

I think a LOT of people buy more airplane than their mission profile really calls for, whether it's a turbo for someone who never leaves their state (unless it's TX, MT, or AK ) or someone who buys a Bo to take two people on short $100 burger runs.

 

[COFlyBoy]

I think a LOT of people buy more airplane than their mission profile really calls for, whether it's a turbo for someone who never leaves their state (unless it's TX, MT, or AK ) or someone who buys a Bo to take two people on short $100 burger runs.

Flying a personal aircraft for pleasure is not really a logical decision, yet we keep trying to come up with rational reasons to make particular decisions about flying.

JayBird, just give up and buy whatever you can afford to maintain given the number of hours you want to fly every month. (I'm assuming you're flying for fun, not a business type mission)

 

[flyingcheesehead]

Valuable Data sir.

BTW, I thought it was clear but my spreadsheet was NOT for a Mooney.

I would guess that the numbers would be similar (we're all flying in the same atmosphere, after all) for aircraft of similar speeds, but I'd suggest you do something similar for yourself. Even better if you can get a POH for each and use those numbers. Best of all, find someone with a J and a K and go up and see how they actually perform.

FWIW, my spreadsheet is for a Turbo Twin Comanche and uses 140 KIAS as the cruise speed at all altitudes. The spreadsheet converts that into KTAS. The other assumptions I used were 1000 fpm climb at 120 knots (25 squared), and 500fpm descent at an average of 180 knots at 23 squared (gotta keep the pax happy and descend at a reasonable rate). So, that ends up being 2 miles per 1000 feet on the way up, and 6 miles per 1000 feet on the way down... That may be part of why I need such long legs to make it worthwhile, since for every 1000 feet I climb, I'll be spending 8 miles climbing and descending. So, on a flight at FL250, 200 miles would be spent climbing and descending! If you're only going 300 miles, it's just not worth it to go that high, and the lower you go, the lower KTAS you get.

The other thing that I don't account for at all is critical altitude. I'm not sure what it is on the Turbo Twinkie. Service ceiling is 30,000 feet with both engines operating, so it should be possible to work backwards from there and estimate it, but I haven't bothered. So, the climb will slow down at some point on the way up, but that would only affect the longest flights. You can't go to 30K with a Twinkie any more anyway unless you spend the $$$ to get it RVSM certified, which would be dumb. I've also seen some that have placards restricting them to 25K, but that's probably the practical limit anyway.

Anyway - All of this is likely somewhat different on a Mooney, so don't take that 160nm too seriously. It's probably not too much different, but go join MAPA and learn.

 

[PittsDriver]

If you aren't going west of Denver, you probably won't get much added value out of a turbocharger.

Although what Ron says in the convention wisdom on this point, I disagree. I've owned the exactly same plane in both the normally aspirated version and the TC version - a Commander 115. I've also owned a Columbia 400 and have time in the Columbia 350. So I think I speak from some significant experience on the contrast between turbo'd or non-turbo'd.

It's unlikely that, living on the east coast, you'll be confronted with flights where you actually need turbo to make the flight. But there are many good uses for it the most important to me being the ability to climb to altitude quickly. My NA Commander would top out on a warm day at about 14,000 and would take a long time to get up above 10,000 - the last few thousand feet being barely at 500 fpm and that's at Vy. The TC would scoot right on up into the teens at 800 - 900 fpm at speed well over Vy so you're getting on down the road at the same time. That's a big difference when you're trying to punch up through a thin layer of ice.

The Columbia 400, with 2.5 people on board and full fuel, would climb at 1300 fpm while making over 160 kts true. That's a big deal in my book. Sure, at the middle altitudes we all fly at, the difference between the Columbia 350 and 400 where not that great in cruise speed. But getting up to altitude quickly is a very useful feature of the turbocharged birds.

I probably can't justify it on cost or otherwise but I'll also just say that we don't fly these kinds of airplanes to go slow and anything that goes faster is a good thing says I.