question about turbocharged aircraft.

[VW Pilot]

Is there a difference between an aircraft with a turbocharger and a plane like a SR-22 or Mooney acclaim which says....our engines are turbo-normalized.....is there a difference?I understand that they have turbochargers but what does it mean when they say Turbo-normalized????

Thanks.

 

[edmulroy]

A turbo-normalized engine is one where the turbo charger is set to provide sea level pressure. To simplify things so that there are fewer pressure on-off cycles they normally set it to about one pound per square inch above sea level (typically set to 16 psi instead of the sea level 14.7 psi).

A turbocharged engine would provide much more than sea level pressure at all times.

The advantage of turbo-normalized is that the engine develops sea level power at altitude while having near normal loads on the engine components for reliability and a long TBO.

The turbo-normalized engine will experience a bit more stress than a non pressurized engine for a couple of reasons. Cooling is often less at altitude and the pressurized air to the cylinders is hotter. An intercooler is often used as a cooling radiator for the pressurized air and does help but does not cool the cylinder air to as low a temperature as if the engine were normally aspirated.

For both turbo normalized and turbocharged engines it is best to have an engine monitor with a cylinder head temperature, CHT, probe for each cylinder. That helps you to monitor CHTs and arrange to not need a top overhaul on an 800 hr engine.

 

[VW Pilot]

Thanks for clearing that up....

 

[Morettis]

Turbo normalized engines you'll see about 29" as the max manifold pressure, same as you'll see in a naturaly aspirated plane at sea level. A turbo charged engine will have manifold pressures well above 29"

 

[avbug]

A few close ideas, but no cigar.

A turbonormalized airplane is a turbocharged airplane. In other words, when you say turbocharged, and turbonormalized, you're saying the same thing.

Turbocharging uses exhaust gasses to increase engine power output, usually (but not always) via increasing induction pressures.

Turbocharging systems use a variety of ways to control the input to the induction system, as a way to regulate the manifold pressure. Systems include manual and automatic wastegates and various control systems...which include turbonormalizing systems. These serve as others have said to limit manifold pressure increase to that of a sea level engine.

Regardless of the value to which a system offers limiting or protection, turbocharging is turbocharging. Turbonormalizing allows a powerplant thus equipped to maintain it's rated power up to a given altitude, as a continuous value. It's simply a turbocharger that's limited to a particular value, but can typically hold that value consistantly to a higher altitude than turbo systems working off a differential basis...consider a turbonormalized engine to be a more powerful one derated for a longer period of time without doing extra work.

 

[MrBojangle]

Avbug=wrong. Turbonormalized and Turbocharged are two different systems. Do yourself a favor and open a book instead of relying on people here with too much time on their hands.

 

[VNugget]

Why don't you enlighten us?

 

[CA1900]

Avbug=wrong.... Do yourself a favor and open a book instead of relying on people here ...

I'm getting popcorn; this is gonna be great...


He's absolutely right, by the way.

 

[Amish RakeFight]

Here's the difference:

Turbonormalizing and turbocharging are accomplished by mechanically compressing the ambient air before it's routed to an engine and used in the normal intake, compression, combustion, and exhaust cycle of operation. Turbocharging systems utilize the same external components as turbonormalizing systems.

The difference between the two is that the compressed air delivered by the turbonormalizing system is limited to the amount of pressure that would be obtained at sea level, or only slightly above (an additional one or two inches), while the turbocharging system increases the manifold pressure to a boosted value above normal sea level pressures (typically an additional six or seven inches, though 10 inches are possible in general aviation airplanes).

For instance, on the turbonormalized Cessna turbo retractable 182 (TR182), the manifold pressure is limited to 31 inches. Because of this limitation, engine manufacturers and the FAA are comfortable with turbonormalizing installations.

Turbocharging forces additional air volume and pressure, over and above what's normal in nature, to be pushed into the engine. This creates more power, but also creates more heat and opens some doors for rapid engine wear because of either uninformed or negligent engine operation by the pilot.

For instance, the takeoff manifold pressure on a mid-1970s Cessna turbocharged 210 (T210) is 37.5 inches. This boosting increases the power output of the engine. In the T210, the takeoff power is 310 horsepower, where without the turbocharging, the same displacement Continental engine in a normally aspirated Cessna 210 only makes 285 hp. Since the manufacturer has boosted the output of the same-size engine, some changes have to be made to the mechanical structure of the engine, such as the installation of lower compression pistons, and stronger cylinders. These changes don't have to be made with turbonormalized engines.

 

[Princedietrich]

Avbug is absolutely correct. On the occasions when he speaks about technical subjects like this, you'd do well to listen.

Hey CA1900, bring me some of that popcorn and I'll wheel in the keg. :beer:

 

[MrBojangle]

Traditional turbocharging boosts air pressure as high as 40 inches of manifold pressure. Turbo-normalizing only allows the air pressure to build to about 30 inches.
Turbo-normalizing means the engine holds sea level pressure as it climbs rather than resorting to high turbo boosted pressures (up to 40 inches) with low compression ratio piston configurations like traditional turbochargers.

So, yes they are nearly identical, but differences do exist. Pass me a keg cup.

 

[svcta]

Avbug=wrong. Turbonormalized and Turbocharged are two different systems.

Doesn't quite have the same meaning as "they are nearly identical".

 

[MrBojangle]

A turbofan and a turbojet are very similar, yet two different systems. Look at the big picture svcta.

 

[Amish RakeFight]

You're getting wrapped up in semantics.

They both fall under the turbocharged umbrella; one just boosts to a higher value.

 

[Mickey]

AvBug gets the win on this one. Sorry MrBOJ..

Didn't you understand Avbugs fourth paragraph?

Avbug saved his typing finger by limiting his response. He could have built one for us if he wanted.

Take care.

 

[avbug]

A turbofan and a turbojet are very similar, yet two different systems.

You sure about that? Are you sure a turbofan isn't a turbojet with a fan on the front?

Traditional turbocharging boosts air pressure as high as 40 inches of manifold pressure. Turbo-normalizing only allows the air pressure to build to about 30 inches.
Turbo-normalizing means the engine holds sea level pressure as it climbs rather than resorting to high turbo boosted pressures (up to 40 inches) with low compression ratio piston configurations like traditional turbochargers.

So, yes they are nearly identical, but differences do exist.

You need to seek a little more education on the subject.

A turbocharged engine which boosts to sea level pressure is said to be turbonormalized...but is still turbocharged.

A turbocharged engine which boosts to a 32" Hg pressure is a turbocharged engine. A turbocharged engine which boosts to a 40" Hg pressure is a turbocharged engine. A turbocharged engine which boosts to a 29" Hg pressure is a turbocharged engine.

If one uses a turbocharger to boost manifold pressure, but relieves that pressure at a given value, one is still turbocharging the engine...which is exactly what is happening in a turbonormalized engine.

 

[Say Again Over]

Some of us understood you the first time, thanks for the recurrent training! As far as the turbo-jet and turbo fan, I say they are VERY different, how they derive thrust, and their operation.

 

[CutEmUp]

Does a turbonormalized engine use an automatic wastegate that is set to regulate the MP to sea level? Do aircraft turbocharging systems have blow-off valves the way cars do to limit total boost when the throttle is closed?

 

[avbug]

Turbonormalized engines do use automatic wastgates; without the use of an automatic wastegate the engine becomes will experience higher boost...which is not the object of turbonormalization. Again, turbonormalization is nothing more than turbocharging the engine to maintain normal sea level manifold pressure.

So far as turbojets and turbofans, they utilize the same principles of construction and operation. A turbofan engine is a turbojet engine with a fan on the front. The core engine doesn't differ considerably from a straight turbojet engine.

 

[VW Pilot]

Wow...... Dick Collins...