Turbo performance question

Irish_Armada

Irish_Armada

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Irish Armada
Okay, I've read up on a # of the threads on turbos vs. NA and I'm still not sure I'm getting it completely.

Let's say I'm flying a Piper Lance out of Lake Tahoe airport on a somewhat warm day, so that density altitude is 8,000. I've got my family of 4 and bags, relatively heavy loaded. Would a turbo Lance be a big advantage in this situation, compared to its NA equivalent? I keep reading that the turbo only really shines at higher altitudes (15k-ish plus), but wouldn't I see a difference and benefit from a turbo in the above example? Or would a NA Cherokee 6 or Lance perform almost just as well, making the turbo mostly an unnecessary expense? My understanding is that in the above example, a NA engine may be performing at 75% power, while a turbo should keep me closer to 100%. Am I missing something? And let's say the same example, but at 5,000 feet density altitude instead. Wouldnt I still see improved performance in a turbo, albeit less than at 8,000? Or is there some kind of altitude limit under which NA and turbos will always perform roughly the same?

I'm not wanting to debate about whether a turbo is worth the added expense and mx headaches (I've read those threads), but just trying to understand where the benefits really are. Thanks!
 
If you're regularly flying to Lake Tahoe (ie in the mountains), especially IFR, I'm thinking you'd regret not getting the Turbo. I have a Comanche 260 and fly out west. Two things I wish I had - turbo and de-ice.


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Irish_Armada said:
Okay, I've read up on a # of the threads on turbos vs. NA and I'm still not sure I'm getting it completely.

Let's say I'm flying a Piper Lance out of Lake Tahoe airport on a somewhat warm day, so that density altitude is 8,000. I've got my family of 4 and bags, relatively heavy loaded. Would a turbo Lance be a big advantage in this situation, compared to its NA equivalent? I keep reading that the turbo only really shines at higher altitudes (15k-ish plus), but wouldn't I see a difference and benefit from a turbo in the above example? Or would a NA Cherokee 6 or Lance perform almost just as well, making the turbo mostly an unnecessary expense? My understanding is that in the above example, a NA engine may be performing at 75% power, while a turbo should keep me closer to 100%. Am I missing something? And let's say the same example, but at 5,000 feet density altitude instead. Wouldnt I still see improved performance in a turbo, albeit less than at 8,000? Or is there some kind of altitude limit under which NA and turbos will always perform roughly the same?

I'm not wanting to debate about whether a turbo is worth the added expense and mx headaches (I've read those threads), but just trying to understand where the benefits really are. Thanks!
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You more or less got it.

You're just making the air more dense by compressing it, even though you are also heating it up with the turbo.
 
James331 said:
You more or less got it.

You're just making the air more dense by compressing it, even though you are also heating it up with the turbo.
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I agree with James (for once) that you've pretty much got it and note that the "heating it up" bit is why an inter-cooler is desirable.

Another way to look at it is that maybe the only way to safely fly the NA aircraft on a high, hot day is to keep it well below max gross. With the turbo you may be able to be up near 90% of max gross and safely operate. Review of the take-off and climb performance charts might be needed. Comparison of the charts for the NA and turbocharged aircraft would highlight the difference in performance.

A side note is that the prop loses a little efficiency when at high density altitudes so turbocharging doesn't cure everything.
 
Depending on the turbo, effectiveness of the intercoolers and such, a turbo plane will operate almost the same at 8000ft DA as it would at sea level DA.

I'm most familiar with the Tornado Alley turbonormalizer system in my SR22 which maintains 30 inHG all the way to FL250 with about a 50 F induction temp increase. That is a twin turbo, twin intercooler system. Taking off from Denver on a hot day is a LOT higher performance than it was in my previous naturally aspirated SR22 with the same IO550 in it.
 
Yes - that is essentially what turbo-normalized means - it doesn't boost higher than sea level pressure (waste gates fully open on the ground) but it maintains that sea level pressure all the way to the critical altitude - in the case of the SR22TN that critical altitude is higher than the airplane's certificated ceiling (FL250). The engine, in essence operates the same at any altitude in the SR22TN. The newer SR22T system boosts a bit above sea level so it is not purely turbo-normalizing.
 
Irish_Armada said:
Okay, I've read up on a # of the threads on turbos vs. NA and I'm still not sure I'm getting it completely.

Let's say I'm flying a Piper Lance out of Lake Tahoe airport on a somewhat warm day, so that density altitude is 8,000. I've got my family of 4 and bags, relatively heavy loaded. Would a turbo Lance be a big advantage in this situation, compared to its NA equivalent? I keep reading that the turbo only really shines at higher altitudes (15k-ish plus), but wouldn't I see a difference and benefit from a turbo in the above example? Or would a NA Cherokee 6 or Lance perform almost just as well, making the turbo mostly an unnecessary expense?
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I would never in a million years attempt a takeoff at 8k DA with my family of 4 in a NA Cherokee 6 unless it was a really long runway and no surrounding terrain.

I have departed from Telluride in a fully loaded Turbo Lance. Not a problem.
 
My Turbo Arrow had mediocre climb performance at sea level, but it could still maintain the same mediocre climb performance at a DA of 10,000 feet. Or close to it anyway.

But the way I look at it, the turbo gets you high altitude performance for mountain flying and efficient cross country trips. Not better IFR capability. Not unless you are equipped for known ice.
 
Sac Arrow said:
But the way I look at it, the turbo gets you high altitude performance for mountain flying and efficient cross country trips. Not better IFR capability. Not unless you are equipped for known ice.
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Where the turbo helps IFR capability is in the Rockies and other parts out west where a NA airplane is hard pressed to reach and cruise at the MEAs.
 
The turbo will deliver sea level power up to about 8000 feet sure enough(model dependent), but the prop and wings will not be as efficient at that DA as they would be at sea level. So, you do gain the performance of the engine back, but the prop and wing are still sitting at your DA altitude.

(BTW, on a 'somewhat warm day' of 76F, the DA would actually be closer to 9000')
 
Fearless Tower said:
Where the turbo helps IFR capability is in the Rockies and other parts out west where a NA airplane is hard pressed to reach and cruise at the MEAs.
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On paper I could make a 16,000 foot MEA over the Sierras if I wanted, but there is no way in hell I'm going to be in IMC at those altitudes, especially in the mountains. An acquaintance of mine shredded his SR22 all over Sugar Bowl trying that.
 
Sac Arrow said:
On paper I could make a 16,000 foot MEA over the Sierras if I wanted, but there is no way in hell I'm going to be in IMC at those altitudes, especially in the mountains. An acquaintance of mine shredded his SR22 all over Sugar Bowl trying that.
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I've regularly seen turbo sr22's file over the rocks into aspen in the winter, no worries. They'll go up to 180 and back down, must be nice!
 
PeeGee said:
I've regularly seen turbo sr22's file over the rocks into aspen in the winter, no worries. They'll go up to 180 and back down, must be nice!
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Winter flying in the Rockies is generally great but the word-to-the-wise is to not do single engine IMC over the rocks. Some folks do it. I might be willing to do it with the proper equipment and conditions which would have to include known-ice cert or a very cold airmass.

I know one guy around here (Denver) with a TKS Mooney and he is pretty much fearless when it comes to icing. Okay, not fearless but doesn't flinch often. As far as I know he is a very safe operator but it's not for everyone.
 
Though do not forget that DA is also dependent on temperature. So while a turbocharger can get your engine down to sea-level pressure, it won't always get you to a sea-level DA. On a hot day in Colorado (90 is not unheard of), the engine would still need to be leaned for takeoff to compensate for the DA of a few thousand feet.
 
BigBadLou said:
Though do not forget that DA is also dependent on temperature. So while a turbocharger can get your engine down to sea-level pressure, it won't always get you to a sea-level DA. On a hot day in Colorado (90 is not unheard of), the engine would still need to be leaned for takeoff to compensate for the DA of a few thousand feet.
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There are cruise power manifold pressure corrections for non-standard temperatures. Those corrections are generally small. For the TSIO-360-FB the correction is 0.4" MAP for each 6 degrees above (add pressure) or below (subtract pressure) standard temperature.

For the TSIO-360-FB the mixture is full rich at maximum manifold pressure...that's how the engine is set up and there are no temperature corrections. When the inter-cooler was added, MAP corrections are made based on temperature drop across the inter-cooler but mixture is full rich at full power. In practice the temperature at the intercooler exit is fairly consistent regardless of OAT. That observation isn't a hard number 'cause in operation I looked at it a few times and said to myself "that temperature doesn't change much" the variation is about 5 degrees. I do track the temperature drop across the inter-cooler and trust it to indicate when something is wrong.
 
I'm a p***y when it comes to ice. I had one bad encounter, that was enough.
 
PeeGee said:
never encountered it.
I saw snow one time last fall and turned my ass around.
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Snow generally isn't bad to fly through since it's already frozen and doesn't stick. I've flown through several snow storms/events including one trip out of the mountains. Visibility is a concern with snow - my advise is don't fly in the mountains during a snow storm unless you know the route well. Horizontal visibility was lousy compared to what we are used to out here in the Rockies but vertical visibility was fine and navigation wasn't a problem. All that said, AOPA has a good safety story about a VFR guy from Montana who flew into a snowstorm in Utah on the way to Salt Lake. He didn't fly out of the snowstorm when he ran out of ceiling in a pass.

Mixed snow and rain can be bad - did that once when I could see through it and knew I'd be in it for less than a minute. I did collect a little ice as expected but the ice came off quickly.
 
Irish_Armada said:
Okay, I've read up on a # of the threads on turbos vs. NA and I'm still not sure I'm getting it completely.

Let's say I'm flying a Piper Lance out of Lake Tahoe airport on a somewhat warm day, so that density altitude is 8,000. I've got my family of 4 and bags, relatively heavy loaded. Would a turbo Lance be a big advantage in this situation, compared to its NA equivalent? I keep reading that the turbo only really shines at higher altitudes (15k-ish plus), but wouldn't I see a difference and benefit from a turbo in the above example? Or would a NA Cherokee 6 or Lance perform almost just as well, making the turbo mostly an unnecessary expense? My understanding is that in the above example, a NA engine may be performing at 75% power, while a turbo should keep me closer to 100%. Am I missing something? And let's say the same example, but at 5,000 feet density altitude instead. Wouldnt I still see improved performance in a turbo, albeit less than at 8,000? Or is there some kind of altitude limit under which NA and turbos will always perform roughly the same?

I'm not wanting to debate about whether a turbo is worth the added expense and mx headaches (I've read those threads), but just trying to understand where the benefits really are. Thanks!
Click to expand...

The turbo allows your engine to develop 100% of its sea-level rated horsepower right up to whatever limit is set for it.

So yeah that Turbo Lance would give you a shorter takeoff roll and better rate of climb, assuming all else is equal. It will also allow you to cruise at a higher altitude if you so desire and continue to develop 100% sea-level horsepower, which results in higher TAS.

Said another way... you'll have 31" Hg (at least) available all the way up with a turbo (though it's often limited to 25" for continuous use).

Your engine can develop full horsepower but your wings still sense the density altitude. So your performance at high-DA certainly will not be the same as it would be at sea level. But your performance relative to a NA airplane in the same conditions will be somewhat better.
 
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I don't think I could ever own a non-turbo. The difference in performance seems pretty drastic to me. My last airplane was a turbo and my current airplane is a turbo. It feels good flying a turbo knowing you are not limited by performance when departing high alt airports or when its really hot and muggy. It really simplifies things as far as planning and terrain concerns.
 
Super helpful replies, thanks everybody. How long did it take you to transition from NA planes to turbo? I've been reading up on the intricacies of in-flight engine/temp management with a turbo, sounds fairly nuanced. My experience is pretty limited, only about 150 hours in a 172s and Cherokee 180s. Do insurance companies have greater time requirements for turbos? I know they do for complex/high performance, but hadn't heard if turbos would require additional time prior to getting coverage.
 
Irish_Armada said:
Super helpful replies, thanks everybody. How long did it take you to transition from NA planes to turbo? I've been reading up on the intricacies of in-flight engine/temp management with a turbo, sounds fairly nuanced. My experience is pretty limited, only about 150 hours in a 172s and Cherokee 180s. Do insurance companies have greater time requirements for turbos? I know they do for complex/high performance, but hadn't heard if turbos would require additional time prior to getting coverage.
Click to expand...

My experience with transition to the turbo Dakota was insurance only wanted one hour with a CFI and there were no requirements on the CFI.

Nuanced? just learn to include manifold pressure, fuel flow, and TIT in your scan. Not really a big deal.
 
Irish_Armada said:
Super helpful replies, thanks everybody. How long did it take you to transition from NA planes to turbo? I've been reading up on the intricacies of in-flight engine/temp management with a turbo, sounds fairly nuanced. My experience is pretty limited, only about 150 hours in a 172s and Cherokee 180s. Do insurance companies have greater time requirements for turbos? I know they do for complex/high performance, but hadn't heard if turbos would require additional time prior to getting coverage.
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About seven months ago I upgraded from a C182 to a turbo C210. The insurance company required 15 hours because I didn't have any retractable time, they were not interested in the turbo. The 15 hours gave me plenty of time to play with the power settings.
I found Deakin's articles on turbos informative. Here is the link to part one
http://www.avweb.com/news/pelican/182102-1.html
My home base is Tahoe, never had any DA probs in the 182
 
Clark1961 said:
My experience with transition to the turbo Dakota was insurance only wanted one hour with a CFI and there were no requirements on the CFI.

Nuanced? just learn to include manifold pressure, fuel flow, and TIT in your scan. Not really a big deal.
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I didn't know they made a turbo dakota, sweet.
 
I was just looking at those -- looks like they only made them with 200hp? Makes it more like a fixed gear turbo arrow...
 
I've always had an image of a turbo's air compression as someone at a hot dog eating contest
joey_20130704152348_640_480.JPG
 
Irish_Armada said:
Super helpful replies, thanks everybody. How long did it take you to transition from NA planes to turbo? I've been reading up on the intricacies of in-flight engine/temp management with a turbo, sounds fairly nuanced. My experience is pretty limited, only about 150 hours in a 172s and Cherokee 180s. Do insurance companies have greater time requirements for turbos? I know they do for complex/high performance, but hadn't heard if turbos would require additional time prior to getting coverage.
Click to expand...

The insurance company couldn't care less about the turbo. They care about complex, HP, and time in type. To them a Turbo Arrow is exactly the same as a NA Arrow, at least for time requirements.

As far as transitioning, it's really a non issue, and engine management is easier if anything, particularly if you have an automatic wastegate. That said, you have to change your practices. You can't be ham fisted with a turbo, and you need to watch your cruise power. A lot of people wear out their turbo engines prematurely from driving them at excessive cruise powers for extended periods because they can.
 
Irish_Armada said:
I was just looking at those -- looks like they only made them with 200hp? Makes it more like a fixed gear turbo arrow...
Click to expand...

It wasn't a popular aircraft obviously since it was only made one year. That said, where I operate, Denver, the aircraft has more power available than a NA Dakota. I've also added an inter-cooler, the Merlyn wastegate controller, and bolted on the -K fuel system for an additional 20 HP along with a few other "goodies". The fuel burn is much better than the NA Dakota except at take-off when it's pumping about 24 gph. In cruise I usually set the fuel flow at either 9 or 10 gph. 10 is peak EGT/TIT for a power setting of 30" & 2400 rpm. It's getting about 15 sm/gallon at 10 gph.
 
Sac Arrow said:
The insurance company couldn't care less about the turbo. They care about complex, HP, and time in type. To them a Turbo Arrow is exactly the same as a NA Arrow, at least for time requirements.

As far as transitioning, it's really a non issue, and engine management is easier if anything, particularly if you have an automatic wastegate. That said, you have to change your practices. You can't be ham fisted with a turbo, and you need to watch your cruise power. A lot of people wear out their turbo engines prematurely from driving them at excessive cruise powers for extended periods because they can.
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True. My engine is an O-540 with a turbonormalizer added on by Cessna.

The AFM says I can use 31" MP during takeoff and occasionally as needed for max performance climb but for cruise it's limited to 17" to 25" MP for that reason. I usually run it at 24"-25" because the AFM says I can and I didn't buy a turbo RG to doddle about. I get 162 KTAS very consistently at 24x23 in the 10-12k ft altitude range. I get up around 170 to 175 KTAS up high. That is flat out hauling ass for a Cessna 182! Add in a tail wind and I've seen 190+ KGS and descending from up high it speeds up immensely and I've seen 215 KGS... in a 182. Pretty effin' amazing to me.

The thing to understand is that at FL200 I often only see 120 to 125 KIAS. That creates a potential oil cooling problem (it's a thing with the TR182's oil cooler position) and is one of multiple limiting factors. I usually run cowl flaps open way up there even though the OAT may be near 0 F. But then again in a descent from FL200 you have about 50 knots of additional indicated airspeed available (assuming smooth air) to speed up. In the time that you go from the very thin air at 20k down into the relatively thicker air below, say, 12k you can let indicated airspeed climb to 160 and haul monstrous amounts of ass.
 
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petrolero said:
True. My engine is an O-540 with a turbonormalizer added on by Cessna.

The AFM says I can use 31" MP during takeoff and occasionally as needed for max performance climb but for cruise it's limited to 17" to 25" MP for that reason. I usually run it at 24"-25" because the AFM says I can and I didn't buy a turbo RG to doddle about. I get 162 KTAS very consistently at 24x23 in the 10-12k ft altitude range. I get up around 170 to 175 KTAS up high. That is flat out hauling ass for a Cessna 182! Add in a tail wind and I've seen 190+ KGS and descending from up high it speeds up immensely and I've seen 215 KGS... in a 182. Pretty effin' amazing to me.

The thing to understand is that at FL200 I often only see 120 to 125 KIAS. That creates a potential oil cooling problem (it's a thing with the TR182's oil cooler position) and is one of multiple limiting factors. I usually run cowl flaps open way up there even though the OAT may be near 0 F. But then again in a descent from FL200 you have about 50 knots of additional indicated airspeed available (assuming smooth air) to speed up. In the time that you go from the very thin air at 20k down into the relatively thicker air below, say, 12k you can let indicated airspeed climb to 160 and haul monstrous amounts of ass.
Click to expand...

I'm pretty convinced the TR182 is about the perfect all around airplane.
I have a share in a straight leg 182 at bjc and hate it with a burning passion.

I'd even take a turbo arrow in the bargain category.
 
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PeeGee said:
I'm pretty convinced the TR182 is about the perfect all around airplane.
I have a share in a straight leg 182 at bjc and hate it with a burning passion.
Click to expand...

For a family of four, I agree. The later Turbo Arrows are up there too. For a 5+ person family then you're into the T 210 or Turbo Saratoga to get 6 places.

For pilots, that 3rd kid gets expensive! :D
 
petrolero said:
For a family of four, I agree. The later Turbo Arrows are up there too. For a 5+ person family then you're into the T 210 or Turbo Saratoga to get 6 places.

For pilots, that 3rd kid gets expensive! :D
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just edited as you posted that.

for us it's just two, so a turbo arrow, mooney, or viking would do also. Arrow probably best value/space. Without a partnership I'm not going to get any of the above :sad:

I flew with a guy that had a turbo saratoga, really, reeeeeally nice plane. I mean, it was like 4 years old too.
 
I am guessing most of those people that replied are not actual turbo arrow or turbo lance owners. I have had a turbo arrow with a Merlin waste gate mod for about 3 years and over 300 hours. The performance is not the same as a standard turbo arrow. That said on mine full power can be maintained all the way up to. 18,000 feet and 75% to 20,000 feet. You cannot firewall this plane even at 15'000 feet I can easily over boost it. I routinely see with accurate full glass cockpit TAS numbers at 11,000 - 12,000 feet of 165 knots over 15'000 feet 174 knots and 17,999 feet 180 - 181 knots at 75% power. My arrow at 75% power will flat run away from any regular aspirated arrow at 75% power as low as 3000 feet. Standard takeoff power is 41 inches of MP with this engine and that happens at sea level at about half throttle. I leveled off at 1000 feet and left the power set at takeoff power for a minute. My indicated airspeed went straight into the white in a heartbeat at 155 knots indicated before I said ok that's enough and throttled back to cruise which gives me 136 to 138 knots INDICATED right on up through those oxygen levels. If I climb at full rated takeoff power at best rate I see 1200 to 1300 fps and cruise climb about 950 fps. Those are the facts with my plane... On my Facebook page I even posted pictures of my panel garmin g500 showing me zipping along at 164 kts TAS at 10,500. Before buying my plane that I now have 320 hrs in I flew a normally aspirated arrow with total time in type of almost 200 hrs. There is no comparison. It is more expensive, but a turbo is $1500 plus install not $5000. Also the standard arrow was a low tail and my turbo is a t tail. I prefer the t-tail and find it more stable in approach with power changes. I have never had any problem landing or taking off in less than a thousand feet on a paved surface at sea level when I tried. That said the turbo will make full power at airports with high density figures but remember the prop has less air to bite so even with full power from the engine it will take longer on the takeoff roll than the experience I shared measured at sea level if you are living where density altitude is high! But then again soooo much better than normally aspirated...
 
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One of the previous posters gave you some incorrect info on insurance. I had almost 200 hours in a regular aspirated arrow and around 350 hours in complex including Mooney's and Cardinal, and 172 RGs. The insurance company could care less about that. My insurance is through Aopa. They wanted to know my total time in a Turbo Arrow! They would in fact not take my instructor who had 6,000 plus hours with lots of turbo and complex, multi, turboprop, etc on insurance to train me until he took my plane by himself for two hours to thoroughly familiarize himself with the plane. They put him as operator on my policy but I was not allowed to ride until he did the checkout. So donT believe it when somebody says it is easy just have complex time... It is a World of difference! Call Aopa and find out for yourself. Time in type for a turbo is that Exact Type of turbo not just another normally aspirated arrow or Lance or another turbo.
 
I broke these up into three parts because I wanted to answer the questions without opinion of whether you should buy a turbo anything... If you have plenty of experience in complex then the advantages of the turbocharger over its naturally aspirated cousin are significant and NOT just at oxygen altitudes. That said there is a Lot more overhead in workload to consider with a turbo. Over boosting is one of those. Except for the really new planes an automatic waste gate is not the same as a turbo-normalized waste gate. You have to watch your throttle settings. Automatic waste gates like my Merlin mean they will adjust to provide full power to higher altitudes.. Example, critical altitude (full rated power) in a standard Turbo Arrow with fixed waste gate is 12,000 feet but with my Merlin it is 18,000 feet. So besides riding the throttle as you climb, you must watch your turbo And cylinder head temps as there is a lot of heat built up! Also not shock cooling the engine is a big thing. You have to plan descents like an airliner does. I usually start my descent from 11,000 about 60 miles out so I can stabilize my descent at about 155 knotts indicated and keep enough power in to not shock cool the engine. I would not recommend any turbo without JPI type engine mgt because of the cooling and heating extremes... That constant 155 knott descent means stepping down the throttle as you go and it will easily jump up in a retractable to 180 knotts Indicated in a heartbeat if you are not paying attention. Also it means arriving at the airport still pretty fast and needing to get down to gear extension and flap extension speeds with again not shock cooling the engine. Then after you land you need a minimum of 5 minutes at idle before shutdown on a turbo. Some of that can be while taxing as long as you are at idle. So my recommendation? Don't get a turbo anything without a Lot of complex experience. But once you have it, it is doubtful you will ever want anything else but a turbo even with the extra expense. After all... Most of us buy airplanes to go fast and it is so much fun in a turbo to scream along and fly right over the center of the DFW Class B and state... Roger, I will remain clear of the class B... I will be Above your Airspace!
 
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