You got that backwards. A turbo uses heat energy, so it can actually make the exhaust after it a bit cooler.SKD_Tech said:The only thing a turbo will do to exhaust is make it hotter. Other than that. Nothing.
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.[email protected] said:You got that backwards. A turbo uses heat energy, so it can actually make the exhaust after it a bit cooler.
The exhaust in a turbo is hotter because it's under much greater pressure to begin with than an NA engine would ever be.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.
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.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
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.EZDUZIT said:Hes right AZ, Just light a match under it and watch it spin![]()
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!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.
Dude, go look at a friggin turbo. Don't study theory. Forget theory. Theory is crap without practical and real world application.[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.
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.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
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.
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.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?
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.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.
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.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.
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.
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.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.
Read Classic Motorbooks SCC's engine and powertrain handbook, the gist of stuff is in their.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.
[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.
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.[email protected] said:You got that backwards. A turbo uses heat energy, so it can actually make the exhaust after it a bit cooler.
Marc Z31 said:Yes, the turbo uses exhaust to power itself, but because of the increased backpressure, it makes the exhaust VERY hot.
Az-Zbum said:Turbo will also smooth it out and act as a preliminary muffler. But it will still be very loud.
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.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.