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.
Turbo will also smooth it out and act as a preliminary muffler. But it will still be very loud.
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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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1992 Yamaha FZR 1000. 145 Hp, all stock..
Last edited by B@lliZtiK : Dec 30th, 2004 at 07:58 AM.
B@lliZtiK: 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.
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B@lliZtiK: 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.
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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1992 Yamaha FZR 1000. 145 Hp, all stock..
Last edited by B@lliZtiK : Dec 30th, 2004 at 10:30 AM.
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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1992 Yamaha FZR 1000. 145 Hp, all stock..
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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Last edited by morepower2 : Dec 30th, 2004 at 12:50 PM.
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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B@lliZtiK: 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.
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.
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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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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