Ford Rethinks Big Block V8s

[Krewat]

Originally Posted by 2000BLK54 You need to stay awake during those classes then. I'm pretty sure that steam turbines are covered in just about any introductory thermo class and they operate on nearly the same principles turbochargers do....heat and mass flow equations. Does steam continue to "burn" after exiting a furnace or even a nuclear reactor, as you've said exhaust gases do with an internal combustion engine? You've just stepped in it. Originally Posted by 2000BLK54 That being said, if heat isn't involved then please explain why companies that make turbocharger test stands use rather powerful gas burners. By your theory all they need is the big air compressor and not the burner. Gee, kid here thinks he knows more than all those engineers. Better tell them what you know so you can save them money. Uh, because they need the heat to produce "real world" environments for testing? -- As said before, take a gas under pressure and measure the temperature, and without even going into any cooling from radiation, suddenly release that pressure and check the temperature again. It'll drop. Go check the propane tank under your gas grill next time you're cooking. Like I said before, the cooling effect of the exhaust gases after the turbo is just a by-product of reduced pressure. Just as the intake charge HEATS UP when compressed, the exhaust charge COOLS OFF when pressure drops.

[2000BLK54]

Originally Posted by krewat

Does steam continue to "burn" after exiting a furnace or even a nuclear reactor, as you've said exhaust gases do with an internal combustion engine?

You've just stepped in it.

Get a clue already. Heat is necessary for a turbo machine to operate efficiently, steam turbines are brought up in early thermodynamics classes which is why I used that example.

Uh, because they need the heat to produce "real world" environments for testing?

Uh, and the other guy and yourself are saying heat isn't necessary. If that is so then why does Honeywell (company that owns Garrett) lists HEAT and pressure as being important to a turbocharger. Heat and pressure. Not pressure with heat as a byproduct. You really think you know more than they?

As said before, take a gas under pressure and measure the temperature, and without even going into any cooling from radiation, suddenly release that pressure and check the temperature again.

It'll drop.

Go check the propane tank under your gas grill next time you're cooking.

Last time I checked propane was a compressed liquid in those tanks and the effect you are so incorrectly trying to apply here is the throttling of a compressed liquid. Show me where in any way, shape, or form is exhaust gas in a compressed liquid state.


You think I stepped in it? You are swimming in it now.

Like I said before, the cooling effect of the exhaust gases after the turbo is just a by-product of reduced pressure.

A like I've said and many experts who make a living on these things, you are wrong. Heat is a form of energy and turbos use part of that energy to drive the compressor wheel. Oh, and getting back to that STS kit again, go do a quick search of those who run those setups and see how they use header wrap.




Just to put a nail in this I'm going to post a few scans from a book on turbocharging from a guy named Corky Bell, you should look it up.

[Krewat]

Nothing there says anything about it being a heat engine. It's important to keep the gases as hot as possible to keep them as voluminous as possible, therefore moving as fast as possible instead of slowing down before hitting the turbine. Or in other words, to keep the pressure as high as possible on the input side of the turbine.

In other words, if the exhaust gases were to cool significantly, the pressure would drop and the turbine would slow down.

It's not a "heat engine" or whatever you are describing. You said earlier the fact that the exhaust gases were cooler on the output side proved that it used heat as a generating force. It doesn't prove anything, it proves that a pressure drop will cause a drop in temperature.

Oh forget it.

[meanv10]

I think he is confusing a turbo charger with a turban engine.

And eventually he will figure that out.

[2000BLK54]

I'm sure you mean turbine engine and no, I'm not confusing anything here. You might want to make sure you've figured things out before giving such advice too.



Only thing confused is the basic understanding of how a turbocharger really works. I've done plenty of my own study, some of you could benefit with a trip to the local library though.

[meanv10]

I never have been a very good at spelling, but i'm also not the one that believes turbos run on magical expanding gas that comes from no were and really has no explanation of what makes it expand after being combusted.

Ya ya got me beat. lol

[meanv10]

How Turbochargers Work - Turbo History

A turbocharger is a dynamic gas compressor or liquid pump, in which a fluid from one stream is pumped, and in the case of a gas compressed, by the mechanical action of an impeller which is powered by a turbine that recovers energy from another fluid stream.


HowStuffWorks "How Turbochargers Work"

*In order to achieve this boost, the turbocharger uses the exhaust flow from the engine to spin a turbine, which in turn spins an air pump. The turbine in the turbocharger spins at speeds of up to 150,000 rotations per minute (rpm) -- that's about 30 times faster than most car engines can go. And since it is hooked up to the exhaust, the temperatures in the turbine are also very high.

One cause of the inefficiency comes from the fact that the power to spin the turbine is not free. Having a turbine in the exhaust flow increases the restriction in the exhaust. This means that on the exhaust stroke, the engine has to push against a higher back-pressure. This subtracts a little bit of power from the cylinders that are firing at the same time.
How Turbos Work
The turbocharger is driven by waste exhaust gases, forced through an exhaust housing onto a turbine wheel. The turbine wheel is connected by a common shaft to a compressor wheel. As the exhaust gases hit the turbine wheel so both wheels rotate simultaneously. Rotation of the compressor wheel draws air in through a compressor housing, forcing compressed air into the engine cylinder.

How Turbochargers Work

Principle of operation

A turbocharger is a dynamic gas compressor or liquid pump, in which a fluid from one stream is pumped, and in the case of a gas compressed, by the mechanical action of an impeller which is powered by a turbine that recovers energy from another fluid stream.


thats the info that backs me up

[Lead Head]

The expanding gasses are coming out of the engine.

[2000BLK54]

Originally Posted by meanv10

thats the info that backs me up

Howstuffworks.com? Grow the hell up. I've already quoted sources that are vastly more comprehensive and better written than the garbage that website has. Why don't you quote a Wiki article or two next?





Figure on this for a minute though. No combustion event is ever 100% complete, there is ALWAYS unburnt fuel exiting the exhaust. Turbos can operate at temperatures that would easily burn off the excess fuel, so what do you think is happening to that unburnt fuel in the turbine section?

Also I stated exhaust gasses are expanding THROUGH the turbine....through it. What part of that do you not understand when others obviously do?

[BURNSTOUGHFORD]

You just posted some copy and pasted crap above, you are no better. You need to grow up and stop insulting people on here.

[2000BLK54]

I posted from a book that is considered a definitive primer on turbocharger systems design. Big difference from Howstuffworks.com which usually has suspect info anyways.

[Krewat]

Originally Posted by 2000BLK54

The temp drop is not a by-product of expanding gas, the temp drop is a direct relation of work/energy transfer from the exhaust gas and the more heat involved the better the transfer takes place.

The above quote is from much earlier in this thread, where you infer that the heat itself is creating work.

It is not, which has been the basis of our argument.

Yes, the hotter the exhaust getting TO the turbo, the better, because it's going to be compressed more, pushing the turbo more because of the pressure drop across the turbine. Keeping as much heat as possible in the exhaust keeps the exhaust backpressure up higher.

The part of your post that I quoted above infers that it's some sort of magic heat engine, using the heat as a direct source of power.

IT IS NOT.

[meanv10]

hey howstuffworks.com is pretty self explanatory to me. lol

[2000BLK54]

Originally Posted by krewat

The part of your post that I quoted above infers that it's some sort of magic heat engine, using the heat as a direct source of power.

IT IS NOT.

Go to the library and read a book already. I've quoted enough sources and you just don't seem to get it. It is not magic, it is a fundamental aspect of thermo- and fluid dynamics. Heat is part of the energy transfer, not just some by-product of a process you don't really understand.

[BURNSTOUGHFORD]

Originally Posted by 2000BLK54

Go to the library and read a book already. I've quoted enough sources and you just don't seem to get it. It is not magic, it is a fundamental aspect of thermo- and fluid dynamics. Heat is part of the energy transfer, not just some by-product of a process you don't really understand.

YES... thermo, fluid dynamics, two areas im well versed in.. an im telling you bud that heat alone will not push the turbo, and 90% of expansion is completed by the time it leaves the engine. you get some further expansion in the cats after they heat up and further chemical process of converting fuels to less toxic gas's

turbo is driven my mdot, which is mass flow rate. it has to do with the speed of a substance and its density. Look up the equations of a turbo and see how much by percent the equation relates mass flow rate and expansion... the expansion you are talking about is minuscule when compared to the mass flow rate of the pistions pushing the mass of air out the exhaust.

sorry man