# Turbocharger: How does it really work....?



## asleepz (Feb 24, 2004)

The only thing a turbo will do to exhaust is make it hotter. Other than that. Nothing.


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## Zen31ZR (Mar 24, 2004)

SKD_Tech said:


> The only thing a turbo will do to exhaust is make it hotter. Other than that. Nothing.


You got that backwards. A turbo _uses_ heat energy, so it can actually make the exhaust after it a bit cooler.


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## Marc Z31 (Jul 25, 2004)

[email protected] said:


> You got that backwards. A turbo _uses_ heat energy, so it can actually make the exhaust after it a bit cooler.


Yes, the turbo uses exhaust to power itself, but because of the increased backpressure, it makes the exhaust VERY hot. A turbo will get up to 200 C hotter than an NA. It will NOT make it cooler. My exhaust hit 850-900 C under full load. If your NA gets that hot, you are too lean.


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## AZ-ZBum (Nov 21, 2004)

Turbo will also smooth it out and act as a preliminary muffler. But it will still be very loud.


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## Zen31ZR (Mar 24, 2004)

Marc Z31 said:


> Yes, the turbo uses exhaust to power itself, but because of the increased backpressure, it makes the exhaust VERY hot. A turbo will get up to 200 C hotter than an NA. It will NOT make it cooler. My exhaust hit 850-900 C under full load. If your NA gets that hot, you are too lean.


The exhaust in a turbo is hotter because it's under much greater pressure to begin with than an NA engine would ever be. 
A turbo uses heat energy, thermal expansion in the turbine chamber, to drive the turbine blades. True, turbos have a little backpressure, but it won't add as much heat as you might think. Depends on the turbo itself, at any rate. Too much backpresure and you'll have problems like the DSMs had, with the turbine chamber inlet and wastegate area cracking. In extreme cases, you'll get problems like the RX7 TTs had, with the wastgate melting under high level boost using the stock turbo setup. If you're running 900C under full boost, you're on the edge of melting something yourself. 900C is very close to the upper limit of what any engine can handle. Maintain that for any length of time and you'll start melting pistons and valves.


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## AZ-ZBum (Nov 21, 2004)

[email protected]: I think you should read about how turbos work again. They do NOT use heat energy or thermal expansion to drive the turbine blades. They are simply driven off the exhaust gas flow. Nothing more.

http://auto.howstuffworks.com/turbo.htm


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> [email protected]: I think you should read about how turbos work again. They do NOT use heat energy or thermal expansion to drive the turbine blades. They are simply driven off the exhaust gas flow. Nothing more.
> 
> http://auto.howstuffworks.com/turbo.htm


Sorry man, but I'm right. How-Stuff-Works is a kiddie site at best. Ask anybody worth a salt on this site, such as Mike K., how a turbo really works. Exhaust gas velocity accounts for about 30% of how a turbo uses exhaust gas energy. The rest is caused by thermal expansion of exhaust gases in the turbine chamber. A turbo is essentially a heat pump.


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## EZDUZIT (Dec 28, 2004)

Hes right AZ, Just light a match under it and watch it spin


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## Zen31ZR (Mar 24, 2004)

EZDUZIT said:


> Hes right AZ, Just light a match under it and watch it spin


It's a little more involved than that. Just a little matter of physics. But hey, don't beleive me. I've asked some of the resident experts to present the facts. Dunno when they'll be in , eventually I suppose.
I'm not gonna bother arguing my point. I took an entire 4 week class on turbocharger theory and operation, so I think I should know what I'm talking about..........


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## morepower2 (Apr 19, 2002)

Marc Z31 said:


> Yes, the turbo uses exhaust to power itself, but because of the increased backpressure, it makes the exhaust VERY hot. A turbo will get up to 200 C hotter than an NA. It will NOT make it cooler. My exhaust hit 850-900 C under full load. If your NA gets that hot, you are too lean.


You are supposed to be an engineering student! A turbo does not make the exhaust hotter! That would be violating the laws of thermodynamics. In fact it makes it around 300 degrees F cooler!

The turbine extracts energy from the exhaust flow. Some of the drive power is expansion and mass flow accross the turbine, The conversion of heat to drive power. Some is pulse energy due to the tuned effects and harmonics of the system. Some is even accoustic energy. Look at some of your books on turbo machines.

Turbos run a higher EGT Pre turbine all things being equal mostly due to the ideal gas law and backpressure but they are in no way making the exhaust hotter, in fact they make the exhaust cooler.


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## AZ-ZBum (Nov 21, 2004)

[email protected] said:


> Sorry man, but I'm right. How-Stuff-Works is a kiddie site at best. Ask anybody worth a salt on this site, such as Mike K., how a turbo really works. Exhaust gas velocity accounts for about 30% of how a turbo uses exhaust gas energy. The rest is caused by thermal expansion of exhaust gases in the turbine chamber. A turbo is essentially a heat pump.


Dude, go look at a friggin turbo. Don't study theory. Forget theory. Theory is crap without practical and real world application.

The gases don't expand in the turbine chamber. If they did, they'd blow those tiny blades apart. Expanding gases create a positive pressure. Pressure alone doesn't spin a turbo. It's the pressure differential between the manifolds and the exhaust port that causes the turbo to spin.

Turbines spin because the air is flowing through the blades. The more air that flows, the faster the turbine spins. All the thermal expansion occurs in the COMBUSTION CHAMBER of the motor. Then, when the exhaust valves are openned, this expanded gas is forced out of the combustion chamber by the upwards moving piston. So all the gases are already expanded as far as they can be. Now they are moving out of the combustion chamber into the exhaust manifolds. But there's more air coming right behind it. And the only place it has to go is out through the turbine. So the blades in the turbine are forced to spin. Because the air in the exhaust manifolds is now slightly pressurized with relation to the air on the other side of the turbine.

btw: a heat pump is NOT a turbo. And vice versa.

heat pump:
http://home.howstuffworks.com/question49.htm
A heat pump is an air conditioner that contains a valve that lets it switch between "air conditioner" and "heater." When the valve is switched one way, the heat pump acts like an air conditioner, and when it is switched the other way it reverses the flow of Freon and acts like a heater.

I guess you might want to ask for your money back for that 4 week course. Use it to buy a book called "Maximum Boost: Designing, Testing, and Installing Turbocharger Systems" by Corky Bell. Once you start reading it, you might have a better understanding about turbochargers and how they work in vehicular applications.


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> [email protected]: I think you should read about how turbos work again. They do NOT use heat energy or thermal expansion to drive the turbine blades. They are simply driven off the exhaust gas flow. Nothing more.
> 
> http://auto.howstuffworks.com/turbo.htm


I think you need to read about how turbos work. I suggest you read turbocharging the high speed internal combustion engine by watson and genoda.

How stuff work is a sight that explains things to a Jr high level.


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## James (Apr 29, 2002)

morepower2 said:


> Turbos run a higher EGT Pre turbine all things being equal mostly due to the ideal gas law and backpressure but they are in no way making the exhaust hotter, in fact they make the exhaust cooler.



This is why EGT gauges are tapped into the manifold before the turbine. If this wasn't the case it would not matter where you tap it into.


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## morepower2 (Apr 19, 2002)

EZDUZIT said:


> Whats up AZ, I know you are the almighty on these cars, but every turbo car had this same problem in the late 70's and early 80's. Buick had the hardest time of them all. The US govenment said it would help aid in burning off unused fuel. So they concidered it a emissions control device( which it was not, I agree) So to make the turbos live longer they tried to keep them extra cool as to not burn up faster.
> Ohh and by the way my 84Turbo is water cooled, Oil lubricated,and air cooled. Factory?


Thats on a diesel engine! In this case turbos help burn the excess fuel reduceing HC and CO but they increse NOX, a much harder pollutant to get rid of. The government never took an official stance on this as far as I know, plese show your source of this information.

Turbos are actualy bad for emmissions, they delay cat light off and increse NOX, hence the lack of CARB approved turbo kits for LEVand ULEV cars.


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## AZ-ZBum (Nov 21, 2004)

morepower2 said:


> I think you need to read about how turbos work. I suggest you read turbocharging the high speed internal combustion engine by watson and genoda.
> 
> How stuff work is a sight that explains things to a Jr high level.


I agree. howstuffworks.com is a great site for the basics. But it doesn't go into detail about properly sizing turbos, understanding A/R ratios, spool up times, etc. But for the basics (which is how they work), it's great. It explains completely how a turbo functions and what it's purpose is.

If you really want to understand turbos and how to properly size a turbo on both the exhaust and intake side, you get the book I mentioned by Corky Bell. It explains a lot more about them as far as properties of adequate sizing and proper cooling of intake charging as well as flow capabilities.


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> Dude, go look at a friggin turbo. Don't study theory. Forget theory. Theory is crap without practical and real world application.
> 
> The gases don't expand in the turbine chamber. If they did, they'd blow those tiny blades apart. Expanding gases create a positive pressure. Pressure alone doesn't spin a turbo. It's the pressure differential between the manifolds and the exhaust port that causes the turbo to spin.
> 
> ...


You are wrong and Ball is right. Read any engineering book on turbomachines. Its expansion accross the turbine that provides the great part of drive force. You are offering a highly simplified view of how a turbo works. Corkey Bell is an engineer but he is also writing in a way that laypeople can easily understand.


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> I agree. howstuffworks.com is a great site for the basics. But it doesn't go into detail about properly sizing turbos, understanding A/R ratios, spool up times, etc. But for the basics (which is how they work), it's great. It explains completely how a turbo functions and what it's purpose is.
> 
> If you really want to understand turbos and how to properly size a turbo on both the exhaust and intake side, you get the book I mentioned by Corky Bell. It explains a lot more about them as far as properties of adequate sizing and proper cooling of intake charging as well as flow capabilities.


I have written and published stuff on how turbos work as well that goes into more detail than corkey bells book. In fact I have several articles on turbo sizing in several major magazines. I think I have a pretty decent working knowlege on applications of turbos and so do some of my friends who design turbos for a living.

You have to take how things work with a gain of salt, its written so a grade school or Jr high level kid can understnad and glean the basics from it. My stuff was written so a high school student that knows some algebra could understand it.


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## AZ-ZBum (Nov 21, 2004)

How and why do gases expand in the turbine? 

What books have you written and what publications have you been published. I am genuinely interested in knowing how and why I'm wrong and what the truth is.


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> How and why do gases expand in the turbine?
> 
> What books have you written and what publications have you been published. I am genuinely interested in knowing how and why I'm wrong and what the truth is.


Read Classic Motorbooks SCC's engine and powertrain handbook, the gist of stuff is in their.

Its not expanding in the turbine like releasing heat energy, its accross the turbine and extracting heat energy this way. I suggest the before mentioned watson and genoda book specficaly for turbos or any collage engineering text on turbomachines.

You need some higher level math but not alot and they are also boring reads unless you are an engineer or a student and maybe even then. Unfortunatly their are no entertaining high level books on the subject but HP wants me to write one. Turbos for dummeys or something like that.


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## Spongerider (Nov 18, 2002)

[email protected] said:


> Sorry man, but I'm right. How-Stuff-Works is a kiddie site at best. Ask anybody worth a salt on this site, such as Mike K., how a turbo really works. Exhaust gas velocity accounts for about 30% of how a turbo uses exhaust gas energy. The rest is caused by thermal expansion of exhaust gases in the turbine chamber. A turbo is essentially a heat pump.












Here is my $.02 to this. 



[email protected] said:


> _You got that backwards. A turbo uses heat energy, so it can actually make the exhaust after it a bit cooler._


I agree that a turbo uses heat energy (exhaust gases are forced through the turbine) but could you explain in more detail why it makes the exhaust a bit cooler? Did I read you right? I know that boost (very high), IC, A/F, timing affect how much heat is produced in the exhaust gases.



Marc Z31 said:


> _Yes, the turbo uses exhaust to power itself, but because of the increased backpressure, it makes the exhaust VERY hot. _


_
Backpressure as I know it is cause by the turbo piping (Length, angle, IC design, exhaust manifold) and exhaust system (precats, cats). I like the way this is stated,

*"Pressurized air is then forced into the engine. Since pressurized air has more oxygen per unit volume (PV = nRT), there is more opportunity for combustion. This additional oxygen can either accompanied by additional fuel for increased power or in some diesel applications, the advantage is in the excess oxygen which allows for cleaner and more complete burning of the fuel, resulting in reduced emissions and increased efficiency."* 



Az-Zbum said:



Turbo will also smooth it out and act as a preliminary muffler. But it will still be very loud. 

Click to expand...


True but my Greddy SP make my Twin Turbo sounds stock. 



Az-Zbum said:



[email protected]: I think you should read about how turbos work again. They do NOT use heat energy or thermal expansion to drive the turbine blades. They are simply driven off the exhaust gas flow. Nothing more.

Click to expand...

I think you were missing his point? The exhaust gases push the turbine blades which in turn forces the compressor (cold side) to force air to compress. This compression occures in the combustion camber so that more air can fit in the same volume (more O2, bigger bang, more heat) . It's a cyclic cycle of sorts. 

Of course this is my opinion which based on my experiance of reading, seeing, and working on my Z. So please don't hurt me!! _


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## AZ-ZBum (Nov 21, 2004)

morepower2 said:


> You need some higher level math but not alot and they are also boring reads unless you are an engineer or a student and maybe even then. Unfortunatly their are no entertaining high level books on the subject but HP wants me to write one. Turbos for dummeys or something like that.


I have a degree in electrical engineering and was doing calculus in 6th grade, so I don't think it will get over my head. :thumbup: Thanks.


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## Spongerider (Nov 18, 2002)

morepower2 said:


> You are supposed to be an engineering student! A turbo does not make the exhaust hotter! That would be violating the laws of thermodynamics. In fact it makes it around 300 degrees F cooler!
> 
> The turbine extracts energy from the exhaust flow. Some of the drive power is expansion and mass flow accross the turbine, The conversion of heat to drive power. Some is pulse energy due to the tuned effects and harmonics of the system. Some is even accoustic energy. Look at some of your books on turbo machines.
> 
> Turbos run a higher EGT Pre turbine all things being equal mostly due to the ideal gas law and backpressure but they are in no way making the exhaust hotter, in fact they make the exhaust cooler.


That more then answered my question thanks!


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## EZDUZIT (Dec 28, 2004)

Thermal expansion is for Jet turbin engines!Air comes in it is mixed with fuel and ignited. Once it is ignited it expands (builds pressure layman's term) then it has to exit somewhere. It is exited through another set of fins, which inturn speeds up the intake turbin which forces more air in which makes a bigger volume explosion which does what you may ask? speeds up theintake even more. 

Now the point to this is that fuel is introduced into this chamber to create thermal expansion inside a jet engine.


A TURBO is feed by? AIR

Thats right AIR, you can turbo charge any car with a compressed air tank with enough volume to feed the turbo. Heck you force out cold air and the Turbo will still spin. If you don't believe that go to the dollar store a by miniture wind-mill. Light a fire under it and see if it turns faster as you blow the hottest air you can come up with on it. I with you on this one AZ-ZBUM, Let me guess a belt driven supercharger uses the heat off the belt to turn it faster. Exhaust has to come out, a turbo utilizes the free outcoming AIR to turn a wheel. ROCKET SCIENCE!


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## James (Apr 29, 2002)

EZDUZIT said:


> Thermal expansion is for Jet turbin engines!Air comes in it is mixed with fuel and ignited. Once it is ignited it expands (builds pressure layman's term) then it has to exit somewhere. It is exited through another set of fins, which inturn speeds up the intake turbin which forces more air in which makes a bigger volume explosion which does what you may ask? speeds up theintake even more.
> 
> Now the point to this is that fuel is introduced into this chamber to create thermal expansion inside a jet engine.
> 
> ...



read above posts.


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## Spongerider (Nov 18, 2002)

I must say, this is a very good discussion on turbos. :thumbup:


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## chimmike (Oct 17, 2002)

AZ-ZBum said:


> [email protected]: I think you should read about how turbos work again. They do NOT use heat energy or thermal expansion to drive the turbine blades. They are simply driven off the exhaust gas flow. Nothing more.
> 
> http://auto.howstuffworks.com/turbo.htm



you're wrong man. Go read Maximum Boost by Corky Bell. That's a turbocharging book, not the stupid howstuffworks website.

Why do you think people thermal coat turbos? To maintain the maximum amount of heat inside the turbine as possible to decrease lag.

Turbos mainly spool off THERMAL EXPANSION. 

In a perfect world where there is no heat soak, turbos would be lag free because there would be no loss of heat in the system.


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## AZ-ZBum (Nov 21, 2004)

A turbo is simply an air pump. It is driven by air. It drives air.

All the other parts about thermal properties and pressures and everything else goes into determining the efficiency of a turbo.

Why is this so hard to understand?



chimmike said:


> you're wrong man. Go read Maximum Boost by Corky Bell. That's a turbocharging book, not the stupid howstuffworks website.
> 
> Why do you think people thermal coat turbos? To maintain the maximum amount of heat inside the turbine as possible to decrease lag.
> 
> ...


Thermal expansion? WTF? Bull crocky.

Do you understand what THERMAL EXPANSION is? It's when a material expands because of heat. Air expanding in a closed system makes the system pressurized. Pressure alone does NOT spin a turbo. Heat alone does not spin the turbo. Heat and pressure together still don't spin the turbo. Heat has absolutely nothing to do with spinning a turbo. The difference in pressures between the two sides causes the turbo to spin. This is because air is now flowing through the turbine blades. And the air on the manifold side is pressurized because the air is being forced out of the cylinders by the pistons coming up and the valves being open. The turbo doesn't cause air to expand inside the turbine. That is done in the cylinders. The air is completely expanded before it even gets to the turbo. The turbo is driven off this moving air. And because the air is going from a pressurized state to a lower pressure state, the air is cooler than when it got in. Which is why the air on the exhaust is lower than in the manifolds (we're still talking over 1000 degrees though).

People thermal coat turbos to keep heat out of the engine bay and in the turbo. Keeping the heat inside the turbo makes it more efficient. It also makes it so you don't cook anything in your engine bay. Why do you think Z32TTs have such crappy wiring harnesses after a few years? It's because the turbos are packing into such a tight engine bay that the heat has no where to go but the engine compartment.

As defined in Maximum Boost.
*Lag:* Lag is the delay between a change in throttle and the production of noticable boost when engine rpm is in a range in which boost can be achieved.
*Turbine:* The turbine is the fan driven by the engine's exhaust gases. It is often called the "hot" side of the turbocharger.

Lag is caused because someone put too big a turbo on a motor and there are not enough exhaust gases at that RPM to create a positive pressure on the compressor side. This can be because the turbine fan is too large, the compressor fan is trying (unsuccessfully) to pressurize too much air, or the engine just isn't moving enough air because it isn't spinning at sufficient RPMs yet.

This isn't rocket science. A turbo is an air pump. Air drives it on the turbine side. It drives air on the compressor side. The engine feeds the air that drives the turbine side. The environment feeds the air that the compressor drives. The coimpressor drives the air that the engine needs. And the cycle continues.

You can't put a big compressor on a small turbine and expect it to work. You can't put a small compressor on a big turbine and expect it to work. You can't put a small compressor and turbine on a 12L diesel and expect it to work. Likewise, you can't put a large compressor and turbine on a 3.0L V6 and expect it to work. This is where the math comes in.

Certain sized turbines require a certain amount of air to drive them and can only flow a certain amount of air max. Same with compressors. And none of this affect the basic principal of the turbo. Air driving air.

All the efficiencies and heat exchanging is what is calculated. And you have to calculate the correct turbine blades and compressor blades sizes and housings to make them produce usable boost.

Repeat after me:
A turbo is an air pump. Nothing more. Nothing less.
A turbo is an air pump. Nothing more. Nothing less.
A turbo is an air pump. Nothing more. Nothing less.
A turbo is an air pump. Nothing more. Nothing less.


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> I have a degree in electrical engineering and was doing calculus in 6th grade, so I don't think it will get over my head. :thumbup: Thanks.


You might try the SAE library as well but I don't have any recomendations from their, they just have a lot of good reference books.


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## morepower2 (Apr 19, 2002)

EZDUZIT said:


> Thermal expansion is for Jet turbin engines!Air comes in it is mixed with fuel and ignited. Once it is ignited it expands (builds pressure layman's term) then it has to exit somewhere. It is exited through another set of fins, which inturn speeds up the intake turbin which forces more air in which makes a bigger volume explosion which does what you may ask? speeds up theintake even more.
> 
> Now the point to this is that fuel is introduced into this chamber to create thermal expansion inside a jet engine.
> 
> ...


You are being a typical internet "expert" you are stating opinion like its fact. I am speaking about known facts that are what any ME studies in school, its not rocket science.

Its heat and expansion that provides most of the drive force for the turbine. Read some of the things I suggested and then you will see how turbos work. They are not POP lituature but textbook level stuff. Or ask any ME or third year engineering student. This is striaghtfoward, not bizzaro technospeck.


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> A turbo is simply an air pump. It is driven by air. It drives air.
> 
> 
> Repeat after me:
> ...


Well, its an energy recovery device as well.


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## Zen31ZR (Mar 24, 2004)

morepower2 said:


> Well, its an energy recovery device as well.


_Heat_ energy recovery, for my 2 cents.

Wow, this is a bigger can if worms than I thought it would be. This thread just might become a sticky for info for those less versed in turbocharger operation and theory.  

Thanks Mike K., Spongerider, James, and anyone else who came in here to back up my cause. Couldn't have done it without you. :cheers:


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## Zen31ZR (Mar 24, 2004)

EZDUZIT said:


> Thats right AIR, you can turbo charge any car with a compressed air tank with enough volume to feed the turbo. Heck you force out cold air and the Turbo will still spin. If you don't believe that go to the dollar store a by miniture wind-mill. Light a fire under it and see if it turns faster as you blow the hottest air you can come up with on it. I with you on this one AZ-ZBUM, Let me guess a belt driven supercharger uses the heat off the belt to turn it faster. Exhaust has to come out, a turbo utilizes the free outcoming AIR to turn a wheel. ROCKET SCIENCE!


Supercharger is a totally different drive system, and completely different in operation. 
As far as blowing on a turbo with compressed air, sure you can do that, and you'll get a few thousand rpm out of it, but I doubt you realize just exactly how fast a turbine spins under expanding exhaust gases. Try over 100,000 rpm, and thats just in a stock boost application. Closer to 160,000 rpm for high level boost. You won't get that kind of rpm simply blowing air on a turbine blade.


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## JAMESZ (Mar 12, 2004)

Whoa I missed alot. In fact I think this is the most in depth discussion that I have ever seen on this forum. To bad I came in late.


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## AZ-ZBum (Nov 21, 2004)

morepower2 said:


> Its heat and expansion that provides most of the drive force for the turbine. They are not POP lituature but textbook level stuff. Or ask any ME or third year engineering student. This is striaghtfoward, not bizzaro technospeck.


How does heat and expansion drive the turbo? Where is the heat generated from? What is expanding? If this is such a simple concept, it should be very easy to explain. So please enlighten us.


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## Spongerider (Nov 18, 2002)

AZ-ZBum said:


> How does heat and expansion drive the turbo? Where is the heat generated from? What is expanding? If this is such a simple concept, it should be very easy to explain. So please enlighten us.


Did you miss what Mike Kojima said earlier?



Morpower2 said:


> You are supposed to be an engineering student! A turbo does not make the exhaust hotter! That would be violating the laws of thermodynamics. In fact it makes it around 300 degrees F cooler!
> 
> The turbine extracts energy from the exhaust flow. Some of the drive power is expansion and mass flow accross the turbine, The conversion of heat to drive power. Some is pulse energy due to the tuned effects and harmonics of the system. Some is even accoustic energy. Look at some of your books on turbo machines.
> 
> ...


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> Where is the heat generated from?


Wait a minute. Surely you know this. In the combustion chamber.


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## AZ-ZBum (Nov 21, 2004)

[email protected] said:


> Wait a minute. Surely you know this. In the combustion chamber.


Exactly! And that's the point. Ignore that other crap about thermal expansion and heat energy. AIR drives the turbo. Plain and simple.

The large volume of air is created in the combustion chamber from the air and fuel taken in at much lower temperatures (like, 1000 degrees lower) and pressurized and ignited thus becoming a much larger volume at much greater temperatures. And this inturn driving the turbo.

There is no combustion, no pressurizing, and no heat expansion taking place in the turbo itself.

my original post that started this whole thing:


AZ-ZBum said:


> I think you should read about how turbos work again. They do NOT use heat energy or thermal expansion to drive the turbine blades. They are simply driven off the exhaust gas flow. Nothing more.


Your reply:


[email protected] said:


> Exhaust gas velocity accounts for about 30% of how a turbo uses exhaust gas energy. The rest is caused by thermal expansion of exhaust gases in the turbine chamber.


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> Exactly! And that's the point. Ignore that other crap about thermal expansion and heat energy. AIR drives the turbo. Plain and simple.
> 
> The large volume of air is created in the combustion chamber from the air and fuel taken in at much lower temperatures (like, 1000 degrees lower) and pressurized and ignited thus becoming a much larger volume at much greater temperatures. And this inturn driving the turbo.
> 
> ...


I see your missing some parts of the system though. Combustion takes place in the engine, the exhaust is forced out into teh exhaust manifold. There is a little bit of expansion of exhaust gases there. From there, the exhaust gases go into the feed tube to the turbine chamber, where the space is very limited. The exhaust gases come out into the turbine chamber, and since it is larger than the feed tube, the gases expand and release heat energy. This is why turbos are located so close to the exhaust manifold, to preserve the heat energy factor. If you notice, in the 80s, some turbo cars, such as the GN prototypes, actually had the turbo located on TOP of the engine, with several feet of exhaust pipe in between the exhaust manifold and the turbo itself. This killed efficiency and turbos on such cars did not work as well. If it were simply a matter of blowing air, turbos could be located as far back as the muffler and still work perfectly fine. But they are not. If you notice, every turbo is loctaed as close as it can be to the head, and using heat energy is the reason for it. Turbo packaging is a nightmare for any engineer, thay have to balance location with efficiency and emissions compliance. Placing a turbo where it is is not because it's _convenient_, it's because it's necessary for proper operation and emissions.


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## AZ-ZBum (Nov 21, 2004)

[email protected] said:


> If it were simply a matter of blowing air, turbos could be located as far back as the muffler and still work perfectly fine. But they are not. If you notice, every turbo is loctaed as close as it can be to the head, and using heat energy is the reason for it.


BS.

read:
http://www.ststurbo.com/


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## Spongerider (Nov 18, 2002)

Az-Zbum, I think your trying to over simplfy things.


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## AZ-ZBum (Nov 21, 2004)

Spongerider said:


> Az-Zbum, I think your trying to over simplfy things.


But a turbo is a very simple device.

We aren't talking about how an ENGINE makes power. We're talking about how a turbo works. What drives it. What it drives. What it does. And what it is is an air pump. Nothing more. Nothing less.


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> BS.
> 
> read:
> http://www.ststurbo.com/


Haha, I fully expected you to pull out that site. Most people do, who have no clue about how a turbo really works. Remote mounting is ok, but notice that none of those applications is yet on a car which has to pass emissions. None of those turbos is on a vehicle old enough yet. They _will_ have problems when they come of age, mark my words. If you notice, the basic turbo provides 5 psi of boost. That far back, thats probably about it's maximum. Turbo "upgrades" can produce up to 20 psi? Heck, most stock turbos can do that normally. That right there tells me there's a major loss of efficiency. The guys that invented that system obviously have never paid attention to the fact that an exhaust system can lose 80% of it's heat through the pipe walls by the time it gets to the muffler. Thats why you can put your hand in front of an exhaust pipe and not get burned...... A turbo system like that does not work to the best of it's ability and will only cause problems later on.


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## Zen31ZR (Mar 24, 2004)

AZ, you're problem is, is that you are good at researching stuff on the internet, but you don't fully understandwhat you are reading. It's easy to pull sites out of anywhere to attempt to explain whatever you want, but you don't seem to understand that not everything on the net is the gospel truth. There's reason why people still write books.  That turbo site that you just pulled out is the perfect example of what I'm talking about. Vehicle manufacturers have been placing turbos where they are for how many years now? And you don't think there's a reason for that? Some site that claims to have remote mounted turbos, now how many of those have you ever seen on any car. Only somebody who barely finished high school, with no engineering knowledge and no school time, and certainly no true automotive knowledge, will ever have one of those devices installed on their car. 

You know what, go on with whatever you think your theories are concerning turbo knowledge, but know this. When you first came here, I respected you for your Z31 knowledge, and I still do. But your knowledge of operations is limited. Stick to what you know. Let the rest of us explain operations.


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## Marc Z31 (Jul 25, 2004)

morepower2 said:


> You are wrong and Ball is right. Read any engineering book on turbomachines. Its expansion accross the turbine that provides the great part of drive force. You are offering a highly simplified view of how a turbo works. Corkey Bell is an engineer but he is also writing in a way that laypeople can easily understand.


A gas turbine engine works in this way, but not a turbocharger. EGT's are hotter on turbo cars because of the severely increased backpressure. The turbocharger works as a product of thermal expansion, but it does not actually have any sort of expansion inside of the turbocharger itself. All of the expansion happens in the combustion chamber, and as it passes through the exhaust manifold, it begins to cool actually. This is the reason racecars have heat wrap on the exhaust manifold, to keep the heat from passing to ambient air. 

The air passing through the compressor housing is more dense and lesser in volume than the gas passing through the turbine side. Yes, the heat makes the turbo work, but there is only contraction of gasses in the turbo itself, from heat lost through exhaust manifolds and the turbine housing itself.


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## AZ-ZBum (Nov 21, 2004)

[email protected] said:


> Haha, I fully expected you to pull out that site. Most people do, who have no clue about how a turbo really works. Remote mounting is ok, but notice that none of those applications is yet on a car which has to pass emissions. None of those turbos is on a vehicle old enough yet. They _will_ have problems when they come of age, mark my words. If you notice, the basic turbo provides 5 psi of boost. That far back, thats probably about it's maximum. Turbo "upgrades" can produce up to 20 psi? Heck, most stock turbos can do that normally. That right there tells me there's a major loss of efficiency. The guys that invented that system obviously have never paid attention to the fact that an exhaust system can lose 80% of it's heat through the pipe walls by the time it gets to the muffler. Thats why you can put your hand in front of an exhaust pipe and not get burned...... A turbo system like that does not work to the best of it's ability and will only cause problems later on.


The 97 TA should have to pass emissions. Besides we aren't talking about emissions. We already know that turbos hinder emissions.

Most of them are only running 5 psi because they haven't upgraded their fuel systems. Most car manufacturers don't ship cars with fuel injectors that can handle twice as much fuel as the car should ever need (the Z31 is a perfect example). Why? Because it's harder to get more precise inections with larger fuel injectors at lower power requirements/rpms.

With reference to the air flow, air flow drives the turbine because of the pressure differential between the two sides of the turbine blades. I agree that the mounting location is not the most efficient and placing the turbo closer to the actual exhaust valves would be optimal, but it does work. There are plenty of dyno graphs up there to prove it.

The only reason I can see to keep the exhaust temps up is to maintain the highest pressures and thus, the highest volumes of air. But I fail to see how temps otherwise help the turbo spin.

How does a turbo require heat to work? What does heat do? How does it benefit the driving of the turbine? Or is it simply to keep the volume of air higher?

edit: I still don't have answers to these questions:
1. How does heat and expansion drive the turbo?
2. Where is the heat generated from?
3. What is expanding?


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## Zen31ZR (Mar 24, 2004)

Marc Z31 said:


> A gas turbine engine works in this way, but not a turbocharger. EGT's are hotter on turbo cars because of the severely increased backpressure. The turbocharger works as a product of thermal expansion, but it does not actually have any sort of expansion inside of the turbocharger itself. All of the expansion happens in the combustion chamber, and as it passes through the exhaust manifold, it begins to cool actually. This is the reason racecars have heat wrap on the exhaust manifold, to keep the heat from passing to ambient air.


 Not all racecars use this "heat wrap". In fact that's old school, they use ceramic coating now and other things. But that is to primarily _INCREASE_ turbine efficiency, for the cooling reasons you described above. Preserving any small amount of extra heat helps the turbo do it's job better. I see you did not read my reply regarding what happens to exhaust gases enroute from combustion chamber to turbo.


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> How does a turbo require heat to work? What does heat do? How does it benefit the driving of the turbine? Or is it simply to keep the volume of air higher?


Essentially correct, it does make for greater volume. That's what is meant by thermal expansion of gases in the turbine chamber, there is actually more volume and flow then there would be otherwise than by simply blowing air on a turbine blade. Same with what Mike K. mentioned about harmonics and other things that happen in the turbine chamber, all this is designed to increase the impelling force on the turbine blades. Simple movement of air is not enough, remember how fast a turbo spins.


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## Marc Z31 (Jul 25, 2004)

[email protected] said:


> I see your missing some parts of the system though. Combustion takes place in the engine, the exhaust is forced out into teh exhaust manifold. There is a little bit of expansion of exhaust gases there. From there, the exhaust gases go into the feed tube to the turbine chamber, where the space is very limited. The exhaust gases come out into the turbine chamber, and since it is larger than the feed tube, the gases expand and release heat energy. This is why turbos are located so close to the exhaust manifold, to preserve the heat energy factor. If you notice, in the 80s, some turbo cars, such as the GN prototypes, actually had the turbo located on TOP of the engine, with several feet of exhaust pipe in between the exhaust manifold and the turbo itself. This killed efficiency and turbos on such cars did not work as well. If it were simply a matter of blowing air, turbos could be located as far back as the muffler and still work perfectly fine. But they are not. If you notice, every turbo is loctaed as close as it can be to the head, and using heat energy is the reason for it. Turbo packaging is a nightmare for any engineer, thay have to balance location with efficiency and emissions compliance. Placing a turbo where it is is not because it's _convenient_, it's because it's necessary for proper operation and emissions.


You have to remember... further in the exhaust system it is less hot, and therefore it takes up less volume. 

Think of it this way. If the turbo had cold air flowing through the turbine housing that took up the same volume as the hot exhaust would, it would still work the exact same way.

It's not the heat that makes the turbo work, it is the increase in VOLUME that makes it work. The temperature has nothing to do with it. If it was cold air (from another source, say a very very large air pump) flowing through the "hot side" at a higher volume than the hot exhaust coming from the engine, the turbo would work BETTER. 

It's NOT heat, it is the increase in volume in comparison to the cold side that makes the turbo work. The increase in volume is caused by heat in an engine, but it is NOT the actual heat that causes the turbo to work. 

Oh, and there is NO expansion in the turbine housing, if anything, there is contraction. Please quit talking out of your ass.

Right on BUM.


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## AZ-ZBum (Nov 21, 2004)

[email protected] said:


> Essentially correct, it does make for greater volume. That's what is meant by thermal expansion of gases in the turbine chamber, there is actually more volume and flow then there would be otherwise than by simply blowing air on a turbine blade. Same with what Mike K. mentioned about harmonics and other things that happen in the turbine chamber, all this is designed to increase the impelling force on the turbine blades. Simple movement of air is not enough, remember how fast a turbo spins.


Yes. I'm aware. 150,000 rpms. Damn fast. And I'm also aware that the more air you force into the engine, the more volume that comes out. So a 3.0L engine at 1bar of boost will effectively be a 6.0L engine. But what it doesn't explain is how gasses expand inside the turbine chamber. Once they get in there, the gasses are trapped between the fan blades and the housing until they exit the exhaust port. So it is only the initial flow of air into the turbine blades that is spinning the turbine, isn't it?


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## Marc Z31 (Jul 25, 2004)

[email protected] said:


> Not all racecars use this "heat wrap". In fact that's old school, they use ceramic coating now and other things. But that is to primarily _INCREASE_ turbine efficiency, for the cooling reasons you described above. Preserving any small amount of extra heat helps the turbo do it's job better. I see you did not read my reply regarding what happens to exhaust gases enroute from combustion chamber to turbo.


It doesn't matter what you use to lock the heat in, it all does the same job. Using rhetorical fallacies and inductive logic does not change the laws of physics.


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> The 97 TA should have to pass emissions. Besides we aren't talking about emissions. We already know that turbos hinder emissions.


 I imagine it will fail, or it's located in a state which does not require emissions. However, that far back and past the catalytic converter, it may not affect emissions much, but the exhaust will cool and condense considerably after the turbo itself. Depending on the turbos location that may in effect make the engine work harder to push out the heavier exhaust gases. I'd like to feel the air coming out of the exhaust on such an equipped vehicle, I imagine the air would be quite cool. If the gases condense too much, the devices used to read the contents of the exhaust gas will not recognize the fact the gases are simply cooler and denser, thus raising ppm content by default, it will simply think ppm content is too high.


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## Zen31ZR (Mar 24, 2004)

Marc Z31 said:


> It doesn't matter what you use to lock the heat in, it all does the same job. Using rhetorical fallacies and inductive logic does not change the laws of physics.


Didn't get past the first couple sentences, I see. Nevermind, I'll no longer attemp to explain anything to you. If you don't beleive me, and certainly not a guy who has written books on the subject, then theres no help for it.


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> Yes. I'm aware. 150,000 rpms. Damn fast. And I'm also aware that the more air you force into the engine, the more volume that comes out. So a 3.0L engine at 1bar of boost will effectively be a 6.0L engine. But what it doesn't explain is how gasses expand inside the turbine chamber. Once they get in there, the gasses are trapped between the fan blades and the housing until they exit the exhaust port. So it is only the initial flow of air into the turbine blades that is spinning the turbine, isn't it?


 There's expansion in between the inlet nozzle and the impeller blades themselves. Yes, it's a very confined space, which makes the expansion that much more effective in driving the turbine. Any expansion after that is in the direction of the rotation , which further drives the turbine.


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## Marc Z31 (Jul 25, 2004)

[email protected] said:


> Didn't get past the first couple sentences, I see. Nevermind, I'll no longer attemp to explain anything to you. If you don't beleive me, and certainly not a guy who has written books on the subject, then theres no help for it.


You are getting a little off subject, but read the longer of my posts. Maybe that will help you to understand what I and BUM are talking about.


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## Marc Z31 (Jul 25, 2004)

Marc Z31 said:


> You have to remember... further in the exhaust system it is less hot, and therefore it takes up less volume.
> 
> Think of it this way. If the turbo had cold air flowing through the turbine housing that took up the same volume as the hot exhaust would, it would still work the exact same way.
> 
> ...


Maybe you should read this again.


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## Zen31ZR (Mar 24, 2004)

Marc Z31 said:


> Maybe you should read this again.


Without the heat, and the consequent expansion, there would need to be a further increase in volume to spool the turbo up to a level that we take for granted. Heat expansion is an important part of how a turbo works, like it or not.


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## Marc Z31 (Jul 25, 2004)

[email protected] said:


> Without the heat, and the consequent expansion, there would need to be a further increase in volume to spool the turbo up to a level that we take for granted. Heat expansion is an important part of how a turbo works, like it or not.


But what you have been saying is that the flow is like 30%, and this is not true. 

What I and BUM have been saying is that it is not the heat, it is the volume.

The heat CAUSES the increased volume, but again, it is ultimately the VOLUME and not heat that causes the turbo to work.


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## AZ-ZBum (Nov 21, 2004)

[email protected] said:


> There's expansion in between the inlet nozzle and the impeller blades themselves. Yes, it's a very confined space, which makes the expansion that much more effective in driving the turbine. Any expansion after that is in the direction of the rotation , which further drives the turbine.


By expansion, do you mean more or less pressure?


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## Zen31ZR (Mar 24, 2004)

Marc Z31 said:


> But what you have been saying is that the flow is like 30%, and this is not true.
> 
> What I and BUM have been saying is that it is not the heat, it is the volume.
> 
> The heat CAUSES the increased volume, but again, it is ultimately the VOLUME and not heat that causes the turbo to work.


But the point we've all been trying to make, is that simple volume is not enough. The heat expansion is required to increase the impelling force, essentially a volume increase, but not in so few words. Besides as Mike K. said other things are at work in the turbine chamber. A turbo is spinning at supersonic speeds in a highly confined area, things tend to work a bit differently.


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## Marc Z31 (Jul 25, 2004)

[email protected] said:


> Without the heat, and the consequent expansion, there would need to be a further increase in volume to spool the turbo up to a level that we take for granted. Heat expansion is an important part of how a turbo works, like it or not.


It's not if I like the heat expansion or not, it's just the simple fact that the increased volume causes the turbo to work. Yes, you are right that the heat causes the volume increase, but you have been wrong in the fact that it is the heat (which must make up a little less than 70% of the operation of the turbo according to your logic) that causes it to work. 

A turbo is an air pump. It's power source could be the exhaust, or ANY other source of gas (at any temperature) that takes up a specific larger percentage of volume than the incoming air fed to the engine.


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## AZ-ZBum (Nov 21, 2004)

[email protected] said:


> But the point we've all been trying to make, is that simple volume is not enough. The heat expansion is required to increase the impelling force, essentially a volume increase, but not in so few words. Besides as Mike K. said other things are at work in the turbine chamber. A turbo is spinning at supersonic speeds in a highly confined area, things tend to work a bit differently.


How does the air get heated and expand inside the turbo? What source creates this heat?


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> By expansion, do you mean more or less pressure?


More pressure, in the direction of impeller rotation. The inside of a turbine housing is made to specifically use this flow and concentrate it, it's not simply a housing for the turbo to sit in. It's just as tuned for specific useage as the rest of the engine is.


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## Marc Z31 (Jul 25, 2004)

[email protected] said:


> More pressure, in the direction of impeller rotation. The inside of a turbine housing is made to specifically use this flow and concentrate it, it's not simply a housing for the turbo to sit in. It's just as tuned for specific useage as the rest of the engine is.


Uh..... :topic: :topic: :topic:


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> How does the air get heated and expand inside the turbo? What source creates this heat?


There is no addition of heat. Not sure where it would be added from. The power cycle in the combustion chamber is the only source. The exhaust gases are over 1000 degrees, coming out of a confined space (the turbine inlet nozzle) into a more open space (the turbine chamber) , expansion pretty much _has_ to happen. As the gases hit the turbine blades, they are also expanding, providing more impelling force. Think of it as throwing a rock at something, and then throwing a stick of dynamite at the same object, exploding right as it touches the target. Which one do you think will go farther, the target hit by the rock, or the target hit by the dynamite........ That's the difference between simple pressurized air flow (as in like the air hose at the gas station), and expanding exhaust gases in the turbine chamber.


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## Zen31ZR (Mar 24, 2004)

Marc Z31 said:


> Uh..... :topic: :topic: :topic:


Housing design is important as well. Tell me it's not.........


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## Marc Z31 (Jul 25, 2004)

[email protected] said:


> Housing design is important as well. Tell me it's not.........


You're not wrong, you're just a little :topic:


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## Zen31ZR (Mar 24, 2004)

Marc Z31 said:


> You're not wrong, you're just a little :topic:


Housing design is what focuses the exhaust gases, and everything else, on the turbine blades. It's pretty important in and of itself.


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## AZ-ZBum (Nov 21, 2004)

[email protected] said:


> Housing design is what focuses the exhaust gases, and everything else, on the turbine blades. It's pretty important in and of itself.


The compressor side focuses the intaken air and pressurizes it. But the exhaust side is primarily responsible for taking the hot pressurized air and making the turbine spin. Compressing the air take energy. Which is what the turbine side is trying to avoid. So no. The turbine side does not pressurize air. It actually unpressurizes the air a bit. Which is why the exhaust after the turbine is cooler than the exhaust on the manifold side of the turbine. The focusing of the exhaust gases onto the turbine blades is what creates the velocity of the exhaust gas. Simple fluids of motion law says that as volume of fluid (exhaust gas in this case) goes from a large cross-sectional area to a smaller cross-sectional area must increase in velocity. The housing does this velocity change. But the turbine itself is just a fan that captures this high speed air.


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> The compressor side focuses the intaken air and pressurizes it. But the exhaust side is primarily responsible for taking the hot pressurized air and making the turbine spin. Compressing the air take energy. Which is what the turbine side is trying to avoid. So no. The turbine side does not pressurize air. It actually unpressurizes the air a bit. Which is why the exhaust after the turbine is cooler than the exhaust on the manifold side of the turbine. The focusing of the exhaust gases onto the turbine blades is what creates the velocity of the exhaust gas. Simple fluids of motion law says that as volume of fluid (exhaust gas in this case) goes from a large cross-sectional area to a smaller cross-sectional area must increase in velocity. The housing does this velocity change. But the turbine itself is just a fan that captures this high speed air.


I think you misunderstood what I said. The shape of the housing simply directs the exhaust gases to, and to remain in contact with, the turbine blades. That's what I meant by "_focus_". I agree with the rest of what you said. :cheers: We seem to be on the same page on a few things.

Well guys, it's been real, it's been fun, but it's not been real fun........Time for me to make my appearance in the real world, I have to go to work. See ya guys tommorrow. Try not to tear the place up while I'm gone, K?


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## AZ-ZBum (Nov 21, 2004)

[email protected] said:


> Well guys, it's been real, it's been fun, but it's not been real fun........Time for me to make my appearance in the real world, I have to go to work. See ya guys tommorrow. Try not to tear the place up while I'm gone, K?


A learning experience it has been. Maybe you could seperate this discussion from the original topic and make it it's own thread? Maybe sticky it or something?

Yeah. I need a drink. Now where'd I leave my bar....


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> How does heat and expansion drive the turbo? Where is the heat generated from? What is expanding? If this is such a simple concept, it should be very easy to explain. So please enlighten us.


Look up the tubine power equation in one of your thermal textbooks from when you were in school.

Temp drop accros the turbine

heat transfer rate-power+mass flow(specific enthalopy before turbine-specific enthalopy after turbine+Velocity before turbine squared-Velocity after turbine squared/2)

Expansion power or reaction is the isontropic enthalopy change in the wheel vs the change in isentropic enthalopy across the whole stage.

These are non-rigorus calculations that don't take into consideration blade geometery swirl losses, etc. I could be wrong, its just off the top of my head.

Its not far off though, I don't have time to really get into this, I could write an article and get paid.


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> A learning experience it has been. Maybe you could seperate this discussion from the original topic and make it it's own thread? Maybe sticky it or something?
> 
> Yeah. I need a drink. Now where'd I leave my bar....


Haha too bad you are in az, discussing this over drinks would be more fun.


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> The compressor side focuses the intaken air and pressurizes it. But the exhaust side is primarily responsible for taking the hot pressurized air and making the turbine spin. Compressing the air take energy. Which is what the turbine side is trying to avoid. So no. The turbine side does not pressurize air. It actually unpressurizes the air a bit. Which is why the exhaust after the turbine is cooler than the exhaust on the manifold side of the turbine. The focusing of the exhaust gases onto the turbine blades is what creates the velocity of the exhaust gas. Simple fluids of motion law says that as volume of fluid (exhaust gas in this case) goes from a large cross-sectional area to a smaller cross-sectional area must increase in velocity. The housing does this velocity change. But the turbine itself is just a fan that captures this high speed air.


But this is only one componet of power recovery that the turbine uses.


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## morepower2 (Apr 19, 2002)

Marc Z31 said:


> A gas turbine engine works in this way, but not a turbocharger. EGT's are hotter on turbo cars because of the severely increased backpressure. The turbocharger works as a product of thermal expansion, but it does not actually have any sort of expansion inside of the turbocharger itself. All of the expansion happens in the combustion chamber, and as it passes through the exhaust manifold, it begins to cool actually. This is the reason racecars have heat wrap on the exhaust manifold, to keep the heat from passing to ambient air.
> 
> The air passing through the compressor housing is more dense and lesser in volume than the gas passing through the turbine side. Yes, the heat makes the turbo work, but there is only contraction of gasses in the turbo itself, from heat lost through exhaust manifolds and the turbine housing itself.


Turbochargers are gas turbines, the negine is the combustor. There is expansion accross the turbine, just like in a gas turbine. The equations for radial flow tubines apply.

Read some engineering level books on tubos. The best one is the aformentioned watson and genoda book, the only trouble is its out of print and you gotta find an old copy in a library.

Its no use arguing, I am speaking from fact, not opinion.


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## morepower2 (Apr 19, 2002)

AZ-ZBum said:


> How does the air get heated and expand inside the turbo? What source creates this heat?


it expands and looses heat.


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## Zen31ZR (Mar 24, 2004)

Ok I'm gonna seperate this from the original _scoop_ thread. Everybody remember where we parked........


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## Zen31ZR (Mar 24, 2004)

Here's a page a little better than the How-stuff-Works page, goes into a tiny bit more detail. http://www.turbochargersnz.com/about.html


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## James (Apr 29, 2002)

[email protected] said:


> Ok I'm gonna seperate this from the original _scoop_ thread. Everybody remember where we parked........


shouldn't this belong in forced induction then?


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## Zen31ZR (Mar 24, 2004)

James said:


> shouldn't this belong in forced induction then?


I'll take it under consideration. It started here, everybody knows where it is, it might as well stay here. Anybody else think it should be moved?


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## Zen31ZR (Mar 24, 2004)

Apparently so. Carry on, gentlemen.


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## asleepz (Feb 24, 2004)

Whoa now I started the thread There is one way to solve this but I doubt anyone would do. Put 2 EGT sensors in their turbocharged car. One Pre-Turbo and one post-turbo.

Anyone?

EDIT I have a nice Pyrometer that I might go check at idle what the temps are. Of course this would just be at idle and the metal temps. I guess it wouldn't be to accurate. It would have to be under boost.


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## BII (May 13, 2004)

I read through this thread and I have a question for the scientists/enginners, as I understand it (my scientific expertise is pretty narrow, I took AP Chem/Physics years ago, and didn't pay much attention at that), what compresses the air (the function we seek since our purpose in turbocharging is getting more air for combustion) is a turbine that spins because exhaust gases expelled by the engine are expanding as they leave the combustion chamber, is it not?

Part 2: IIRC from physics/chemistry class, pressure and heat are directly related, yes? If that is the case, it is not so much that a turbo _uses_ heat, but the amount of heat decreases because the exhaust gas is expanding as it cools (the amount of gas didn't change, its just taking up more room, boyle's law?). This is bernoulli's (sp?) principle happening to the turbine blades isn't it?

Please don't flame, I'm just trying to relate it to my level of schooling so I can expand from there.


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## Zen31ZR (Mar 24, 2004)

bII said:


> I read through this thread and I have a question for the scientists/enginners, as I understand it (my scientific expertise is pretty narrow, I took AP Chem/Physics years ago, and didn't pay much attention at that), what compresses the air (the function we seek since our purpose in turbocharging is getting more air for combustion) is a turbine that spins because exhaust gases expelled by the engine are expanding as they leave the combustion chamber, is it not?
> 
> Part 2: IIRC from physics/chemistry class, pressure and heat are directly related, yes? If that is the case, it is not so much that a turbo _uses_ heat, but the amount of heat decreases because the exhaust gas is expanding as it cools (the amount of gas didn't change, its just taking up more room, boyle's law?). This is bernoulli's (sp?) principle happening to the turbine blades isn't it?
> 
> Please don't flame, I'm just trying to relate it to my level of schooling so I can expand from there.


Mike Kojima would be the guy to ask on that, I'm not 100% on the physics. He'll prolly just tell you to read the books mentioned earlier in this thread, though.  

There is constant heat loss going on , from the second the exhaust gases leave the combustion chamber. This is why typically a turbo is located as close as it can be to the combustion chambers, to make best use of the hot exhaust gases. 99% of all factory turbo cars have the turbos mounted just a few inches away for exactly this reason. Otherwise it wouldn't matter where the turbo was located, and it would more likely be located much farther downstream, just because packaging is such a pain. Engineers don't mount turbos right in the engine bay just for fun. 
It has been mentioned that there are turbo kits that mount the turbo almost back by the muffler, but these are a pretty ineffective use of a turbo, mostly low psi systems on high compression cars, such as Trans-Ams with LT1s......Not to mention it has to be pretty laggy. That far back, exhaust gases simply don't have the "punch" they do right out of the exhaust manifold, turbos back that far are relying on pure volume and whats left of the velocity, if you notice cars with turbos that far back also have much smaller exhaust piping, to maintain and increase velocity lost as heat is lost throught the pipe walls....
Turbos use the expansion of gases in the turbine chamber, as well as volume and good old velocity, as well as the harmonics of the supersonic sound waves present in the turbine chamber. Mike Kojima has already mentioned this over the course of the thread, though, and you would do well to read every reply......


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## velardejose (Sep 9, 2004)

Hi
Theoretically speaking, a non water cooled turbo would be the choice? It works hotter...
I have a question
The closer it is to the combustion chamber the more efficient it is, its clear
Thing is, as close as possible to the cc with unequal primary tube lengths vs same length primary tubes but not so close to the cc, which is better?
Thanks in advance


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## chimmike (Oct 17, 2002)

a non-water cooled turbo makes no difference to the power the turbo makes.

water cooling is used to prevent the need for a turbo timer by keeping the center section cool so that hot oil doesn't coke up the bearings once the car is turned off.


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## velardejose (Sep 9, 2004)

Thanks for that data, I didn't knew it
And the primary-tube-equal-length vs as-close-as-possible to the combustion chamber thing?


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## chimmike (Oct 17, 2002)

velardejose said:


> Thanks for that data, I didn't knew it
> And the primary-tube-equal-length vs as-close-as-possible to the combustion chamber thing?



close to the combustion chamber won't work as well as equal length simply because, as you know, not all of your cylinders fire at the same time.

the equal length takes those individual pulses and smooths them out into useable flow and thermal expansion for spinning the turbine.

just because it's close to the combustion chamber doesn't necessarily mean it'll spool faster because the flow will be turbulent from the ports.

another, better design, is the pulse converter design, which essentially makes the length of each runner according to the firing order of the cylinder so as to make the flow to the turbine equal, as if all the cylinders were firing at the same time, perpetually.


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## Zen31ZR (Mar 24, 2004)

velardejose said:


> Hi
> Theoretically speaking, a non water cooled turbo would be the choice? It works hotter...
> I have a question
> The closer it is to the combustion chamber the more efficient it is, its clear
> ...


 The "bundle of snakes" manifold setup is best, timing the exhaust pulses in a linear fashion, keeping a more constant source of heat and pressure going into the turbine chamber.... But if you notice, they are still located extremely close to the combustion chambers. Factory exhaust manifolds are not built to maximize performance such as these are. 
Water-cooled turbos have coolant running through the center housing to simply keep the extremely hot center section from frying the oil when the engine is turned off, and during periods of low oil flow such as at idle rpm. The water temperature does not affect actual turbine operation in the slightest. There are oil only turbos, where the oil provides cooling as well as lubrication, but the oil flow and galley size in those is much larger than factory water cooled turbos. As I recall, most oil only turbos are also ball bearing, which tend to operate much cooler (in the center section) and also require less oil than conventional oil bearing turbos.
But I digress, chimmike has already explained all this. :cheers:


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## chimmike (Oct 17, 2002)

thanks captain rehash


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## velardejose (Sep 9, 2004)

Thanks a lot


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## z31 (Oct 19, 2004)

bII said:


> what compresses the air ... is a turbine that spins because exhaust gases expelled by the engine are expanding as they leave the combustion chamber, is it not?
> 
> Part 2: IIRC from physics/chemistry class, pressure and heat are directly related, yes? If that is the case, it is not so much that a turbo _uses_ heat, but the amount of heat decreases because the exhaust gas is expanding as it cools. This is bernoulli's (sp?) principle happening to the turbine blades isn't it?


1: The exhaust flow does work on the turbine, that work is transferred the the compressor side via a shaft. The compressor compresses (oddly enough ) the air.

2: Yes, pressure, temperature and volume are directly related.

work done by a turbine is the sum of the ethalpy, kinetic energy, and potential energy changes of the media (air in this case).
The contention in this thread is the ethalpy term apparently.


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## BII (May 13, 2004)

Enthalpy is how much work the expelled exhaust gases can do right? If so, than as the volume of the exhaust gases increase, the faster it can compress right? Also if H = E + PV ( Enthalpy = Energy + (Pressure*Volume) ), than more heat means more work can be done, yes? Therefore turbos DO use heat to compress air and it does make sense to keep the turbine close to the combustion chamber, since that is when the gases are the "hottest" and therefore have more energy. This also explains why turbos do run make exhaust cooler.


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## Zen31ZR (Mar 24, 2004)

bII said:


> Enthalpy is how much work the expelled exhaust gases can do right? If so, than as the volume of the exhaust gases increase, the faster it can compress right? Also if H = E + PV ( Enthalpy = Energy + (Pressure*Volume) ), than more heat means more work can be done, yes? Therefore turbos DO use heat to compress air and it does make sense to keep the turbine close to the combustion chamber, since that is when the gases are the "hottest" and therefore have more energy. This also explains why turbos do run make exhaust cooler.


 I think you are the only person so far to have reasoned this out...... :cheers:


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## morepower2 (Apr 19, 2002)

SKD_Tech said:


> Whoa now I started the thread There is one way to solve this but I doubt anyone would do. Put 2 EGT sensors in their turbocharged car. One Pre-Turbo and one post-turbo.
> 
> Anyone?
> 
> EDIT I have a nice Pyrometer that I might go check at idle what the temps are. Of course this would just be at idle and the metal temps. I guess it wouldn't be to accurate. It would have to be under boost.


doesnt have to be solved, its been solved for decades.


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## morepower2 (Apr 19, 2002)

[email protected] said:


> The "bundle of snakes" manifold setup is best, timing the exhaust pulses in a linear fashion, keeping a more constant source of heat and pressure going into the turbine chamber.... But if you notice, they are still located extremely close to the combustion chambers. Factory exhaust manifolds are not built to maximize performance such as these are.
> Water-cooled turbos have coolant running through the center housing to simply keep the extremely hot center section from frying the oil when the engine is turned off, and during periods of low oil flow such as at idle rpm. The water temperature does not affect actual turbine operation in the slightest. There are oil only turbos, where the oil provides cooling as well as lubrication, but the oil flow and galley size in those is much larger than factory water cooled turbos. As I recall, most oil only turbos are also ball bearing, which tend to operate much cooler (in the center section) and also require less oil than conventional oil bearing turbos.
> But I digress, chimmike has already explained all this. :cheers:


Its a trade off, the shorter the primary tubes, the better the turbine efficenciy, the longer and closer to the proper tuned length, the VE is better but the TE falls off. When I design a turbo manifold, I use a harmonic of the tuned length for a shorter runner and use a pulse converter design pairing cylinders 1-4 and 2-3 so pulse energy and heat energy are best ustilized.


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## morepower2 (Apr 19, 2002)

[email protected] said:


> I think you are the only person so far to have reasoned this out...... :cheers:


Thats what I wrote out but no one understood it.


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## Zen31ZR (Mar 24, 2004)

morepower2 said:


> Thats what I wrote out but no one understood it.


You're just too far over everyones head.......


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## z31 (Oct 19, 2004)

[email protected] said:


> I think you are the only person so far to have reasoned this out...... :cheers:


All that was needed was the equation for work done by a turbine :cheers: 

"In this house, we obey the laws of thermodynamics!"
-Homer Simpson


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## velardejose (Sep 9, 2004)

thermodynamic is a helpful science 
morepower, any pic of a turbo header designed that way?


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## Zen31ZR (Mar 24, 2004)

velardejose said:


> thermodynamic is a helpful science
> morepower, any pic of a turbo header designed that way?












Heres just one design, for a 4G63, T4 turbo application.  

Pics of many other kinds can be seen Here


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## velardejose (Sep 9, 2004)

Thanks a lot
I'll build it next week
I am fabricating the conectors for the oil feed and return, and already got a bov from a toyota glanza
I'll post pics
Btw anybody knows if the ct9 turbo can be used in a draw through config?
Thanks in advance


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## Zen31ZR (Mar 24, 2004)

velardejose said:


> Thanks a lot
> I'll build it next week
> I am fabricating the conectors for the oil feed and return, and already got a bov from a toyota glanza
> I'll post pics
> ...


Want to elaborate a little more on what you're doing?


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## morepower2 (Apr 19, 2002)

*Split Thread*

To do carbed systems suck.


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