Turbocharger

[niemeyjt]

apologies - should have written "run at idle"

J

 

[SPYDERLK]

I am not sure about that. There is lot of energy in the exhaust gases. The turbine uses the energy to run compressor that in turn helps to overcome suction losses.
[snip]
I also noticed that some manufacturers use the same engine producing power from in example 67 to 90 HP. That is apparently possible by changing, among other things, turbocharging pressure. Turbocharging allows for power as well as torque increase without rpm increase.

Absolutely, and its very good to make use of that energy. By doing it in this manner tho, running a turbine, you have to look at any energy offsetting cost it has. This use increases the exhaust backpressure on the engine making the engine do more work on its exhaust strokes. With a NA engine the exhaust can be tuned to help evacuate the cyls completely - - and also the compression ratio is significantly higher leaving very small remanent exhaust gas in the cyl to corrupt the intake. The turboed engine runs at a slight disadvantage because of this, and hence a lesser fuel efficiency, but in comparison to NA, gets it back in the higher parts of its power range because it does not have to be run "rich" to get there.

In your example, that NA engine running comfortably within its range producing 60HP is slightly more fuel efficient than that same turbo optimized engine is when it is producing 60HP. The turbo one tho has plenty in reserve before its efficiency falls, while that of the NA is already falling as more fuel is added to get as much burn [power] from the limited air charge as possible.
larry

 

[Redneck in training]

What you are saying might be true about automobile engines. Tractor engines are virtually constant speed. Therefore the valve timing and turbocharger size can be optimized. The turbo increases backpressure but the exhaust downstream of the TC has less resistance due to lower velocity of the gases and since a lot of energy was removed by the turbo the muffler can also be less efficient (restrictive) for the same noise level. In addition to it the timing of the exhaust valve can be such that some air is actually blown to the exhaust completely flashing the combustion chamber. I think that TC engines are in overall more efficient. But that is just my opinion.

 

[Chilly807]

In my experience, which is mostly marine diesels, turbocharging gets you more power out of a given displacement, fuel economy will be better for the same rated horsepower delivered as well.

The amount of boost you can safely apply depends on the engine design, it has to be built to withstand the extra stress the increased power brings with it. It's why turbocharging an engine that was designed around natural aspiration (non-turbo use) is discouraged. Most of the stuff I work on has anywhere from 20 to 45 psi of boost at full load. At lower loads the intake manifold runs in a vacuum state, as power output and exhaust gas flow increases, turbo speed rises and a pressure develops in the intake.

Most vehicles are built to accomodate an engine of X x Y x Z dimensions, turbocharging or supercharging that engine allows you to deliver more power per litre of displacement. Marine use is no different. When you have an engine room of a given size depending on the size of the ship, and you need a given horsepower value to give you X knots, it definitely limits your choices.

I'm not a big fan of turbo-charged tractors, at least not the smaller displacement ones most of us here have. I believe the added complexity and cost outweighs the benefits. I don't burn enough fuel for the increased economy to make an appreciable difference, and there's plenty of room under the hood anyway.

Tractors that are primarily used for steady load ground engagement, such as plowing, tilling, etc, will see the most benefit, while those that are used for loader work or off-on load will see the least advantage.

Chilly

 

[Redneck in training]

In my experience, which is mostly marine diesels, turbocharging gets you more power out of a given displacement, fuel economy will be better for the same rated horsepower delivered as well.

The amount of boost you can safely apply depends on the engine design, it has to be built to withstand the extra stress the increased power brings with it. It's why turbocharging an engine that was designed around natural aspiration (non-turbo use) is discouraged. Most of the stuff I work on has anywhere from 20 to 45 psi of boost at full load. At lower loads the intake manifold runs in a vacuum state, as power output and exhaust gas flow increases, turbo speed rises and a pressure develops in the intake.

Most vehicles are built to accomodate an engine of X x Y x Z dimensions, turbocharging or supercharging that engine allows you to deliver more power per litre of displacement. Marine use is no different. When you have an engine room of a given size depending on the size of the ship, and you need a given horsepower value to give you X knots, it definitely limits your choices.

I'm not a big fan of turbo-charged tractors, at least not the smaller displacement ones most of us here have. I believe the added complexity and cost outweighs the benefits. I don't burn enough fuel for the increased economy to make an appreciable difference, and there's plenty of room under the hood anyway.

Tractors that are primarily used for steady load ground engagement, such as plowing, tilling, etc, will see the most benefit, while those that are used for loader work or off-on load will see the least advantage.

Chilly

If I understand it right to meet TIER II standards the manufacturers use TC without intercooler. To meet TIER III they use TC and intercooler. Therefore all new tractors are turbocharged.

I also read somewhere that some WWII piston aircrafts had engines with turbines not only running the compressor but were also coupled with the cranckshaft. The turbine added about 10% of power at low altitudes when the compressor was not needed.

 

[niemeyjt]

I also read somewhere that some WWII piston aircrafts had engines with turbines not only running the compressor but were also coupled with the cranckshaft. The turbine added about 10% of power at low altitudes when the compressor was not needed.

Certainlythe Rolls Royce Merlin engines were supercharged - which is what you describe - as fitted to the likes of Spitfires, Hurricanes and Lancasters.

Rolls-Royce Merlin - Wikipedia, the free encyclopedia

The sound is amazing when they fly over from time to time.

J

 

[Chilly807]

Generally speaking, any engine which uses a form of compressor on the intake system is said to be "supercharged", turbocharging is a variation of that which uses a turbine to drive the compressor, usually driven by exhaust gas.

Detroit Diesel engines (2 stroke variety) use a mechanical supercharger driven off the geartrain to provide scavenging air and a mild boost effect. Some of those also use exhaust gas turbochargers in series with the supercharger to further increase the intake pressure. A "blower bypass" system is used to circumvent the mechanical blower at higher loads when the turbos are able to provide more air flow and higher pressures. Most of those are also intercooled.

Larger engines often use sequential turbocharging to provide better performance from a smaller turbo at lower loads, then gradually change over to a larger turbo at high loads. Getting more complicated here..

Which way does the "tier" system work? If higher numbers mean later requirements, my non-turbo Kubota engine is "interim" tier 4 compliant as of now. Diesels are problematic with clean air requirements to begin with, making them cleaner is going to be more difficult than gas engines.

As someone else mentioned, supercharging allows more fuel to be burned effectively, with better (meaning more power) combustion. How much cleaner they actually run, environmentally speaking, is another question.

Sean