Turbos operate off of pressure differential. Heat is the greatest contributor to the pressure differential. They are thermodynamic machines.

 

When it all comes to rest, in the end an engine is a giant air pump. A turbo or a supercharger just fools it into thinking it is a larger pump than it is by increasing the volume of air entering the engine than would be entering the engine at ambient air pressure.

 

You are right - my point is, that the pressure comes from the temperature increase during combustion. The Turbocharger is an additional device that capitalizes of energy that would typically be radiated out to the environment.

If you take a turbo engine, and rotate it - without igniting fuel. How much boost will it make?
Sure, but WHY can it build pressure?
Because of the temperature of the air.
Its similar, but only its the opposite way around.

In a refrigerator you impose a pressure change in the gas (compress it) which creates a temperature change.

In this - its the other way around. You invoke a temp change, (combustion) which creates pressure.They are both combustion engines, a gas turbine is just a turbo and is an external combustion engine.
Compress air, introduce fuel, ignite - use the temperature invoked on the air/fuel mixture to create a pressure change and drive the turbine.

 

alright if heat does not play a role in a turbo then how come this morning i started up and left my driveway and as soon as i hit pavement i stomped on my truck (not that i do that all the time) and the most boost i made was 19 pounds. then after truck warmed up i did it again and then made 27 pounds of boost. i know oil was cooler at first but it still should have been at least 80 degrees when i started up.

 

This situation of a cold-engine boost, has a number of different variables to it. If you're running aftermarket tuning, most don't allow for full fueling unless the engine is at or near OT. The viscosity of the oil, and coolant for that matter at 80* is much different than at the 180*+ the engine is designed to run at. An 8psi difference in boost pressure on the 6.0L could be attributed to the electrical programming, preventing a lack of lubrication from causing excessive engine wear.

Again here's the point I'm making. Take a turbo off the motor, apply whatever heat source you feel will mimic the BTU's of radiated heat and see if it spins. Its not physically possible to spin a turbo off heat. Take that turbo and put air flow through and pressure (ambient temps), and it will create boost. It say heat has nothing to do with the equation is closed minded, as the pressure is created initially but fuel combustion, but the gasses are not longer expanding and once they leave the engine.

 

The point I believe Porchfarms is making is this: the hotter air is much more effective at spinning the turbo than "cold" air. Which is 100 percent correct.

Pressure is a part of making the turbo function, but heat is what accelerates (very rapidly) the process.

 

agreed and agreed.

 

In a jet engine configuration it is, I think this is why all sorts of facts and figures are getting thrown around here.

Technically it is an "engine" but I think that is such a far stretch in this truck configuration.

Think of it as an air powered air pump.

 

The turbo in a diesel does not function the same as a Jet Turbine. Similar, however a jet turbine creates its own power from fuel. A turbocharger does not create its own power, that power must come from a source of air. Diesel exhaust is that airflow in these trucks.

 

thank you, you nailed my point. i guess this arguement can also relate to tires. check your pressure when the tires are cold then check them after driving a while, same amount of air but different pressures.

 

Wrong, a jet engine makes most of its power from compression via low pressure and high pressure turbines. Yes there is an igniter and afterburners do add a ton of thrust (at the expense of a ridiculous amount of fuel that is not sustainable for more than a few seconds at a time) but most of it is pressure. Hell, a ramjet operates on ONLY pressure and those things can make it all the way to Ludicrous speed.

From just reading the last few pages of this thread, there are a few people who really need to learn how a turbocharger actually works and how different one turbo app can be from another even with similarly sized motors. It isn't like an actual coal/nuclear powerplant where steam (exhaust) heats up and drives a turbine to turn at a fixed rate. There is a LOT to do with AR selection, housings, compressor blades, turbine blades etc...

 

Uhh yeah, but a jet engine runs from a heat source.

It draws it's own air in, and expels exhaust but it does not require external forces to run.

The combustion is ongoing and causes the machine to run from heat.

In a jet engine, it is possible to run it exclusively from heat, and I stand by what I said. All you need to do is heat the air with whatever method you choose, and as long as you can get the BTU to the air, it will do the same job as any fuel.

 

Doesn't suprise me that a 7.3 has gone over 1 million miles seeing as how they are made by International. Most big diesels in semis made by International and others are designed to go that long with just routine maintenance.

 

Hey porch, I'm not sure what ur saying here. I think I've missed a page. I've been tied up w/ our wheat harvest.we're cutting 90-110bu an acre so I don't have much time to keep up.I've never seen 67 lb TW wheat before.
Anyway, cooler air outside should help you. When you compress air it gets hot. So you need the CAC to cool the compressed air because warmer or hotter air's molacules are spread out. You want dinser air going into the combustion champer. The closer the molacules the more the air. A tire has a higher pressure when hot because the air expaned its not anymore air.
The thing about the wheel turning above candles happen because as the air heats up it rises. So it moves. Ots still air its just that the mocules start moving around. If you have a surface that can catch the moving air you can harness the energy.
There pressure from the combustion. This pressure can be built by anything put in the exhuast system. Wiether its an exhaust brake, turbo, cats, or a muffler. An exhaust brake works by using and increasing this pressure. Heat its self isn't turning the turbine its the pressureized spent gasses coming from the engine. Turbos are built w/ materials to displace the heat. Heat actually is a enemy of the charger system.

 

Engines in pickup trucks have it hard.