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> New types of turbo's in the works., Interesting....READ!!
post Jan 6, 2005 - 5:22 PM
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shid



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QUOTE(WannabeGT4 @ Jan 6, 2005 - 10:13 PM)
QUOTE(shid @ Jan 6, 2005 - 4:05 PM)
QUOTE(WannabeGT4 @ Jan 6, 2005 - 9:27 PM)
QUOTE(Jehuty @ Jan 6, 2005 - 3:21 PM)
1. Turbines are spun be HEAT. That's why turbos are mated right up to manifolds. Putting the turbo way back there looks like a good way to shed alot of heat....
[right][snapback]230750[/snapback][/right]


You sure about that?
[right][snapback]230755[/snapback][/right]


he's not right, but he's not entirely wrong- hotter air out of the manifold will spool up the turbo faster; having the turbo far away from the manifold (allowing air under the car truck to cool it (but not by much) is going to lower the amount of air pressure spinning the turbine, leading to a longer spool time (maybe like... 20 miliseconds smaller? Exhausts are still friggin hot wink.gif
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Didn't say anything about air pressure so it sounded like he was saying only heat is responsible, which is completely wrong. wink.gif
[right][snapback]230767[/snapback][/right]


the hot air expanding into the tiny space of the manifold is what causes the pressure wink.gif

but yeah, who knows if thats what he was thinking. hmm
post Jan 6, 2005 - 10:01 PM
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biglipzit

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imagine forgetting a speed hump at night doing 40mph with one of those rear mounted turbos lmao
post Jan 6, 2005 - 11:09 PM
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QUOTE(biglipzit @ Jan 7, 2005 - 3:01 AM)
imagine forgetting a speed hump at night doing 40mph with one of those rear mounted turbos lmao
[right][snapback]230873[/snapback][/right]


Man, I love how in europe they call them humps.
post Jan 6, 2005 - 11:25 PM
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biglipzit

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We also call them sleeping policemen... Do yall use that one?
post Jan 7, 2005 - 1:23 AM
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97sccelica



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QUOTE(biglipzit @ Jan 6, 2005 - 8:25 PM)
We also call them sleeping policemen... Do yall use that one?
[right][snapback]230910[/snapback][/right]


strange


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post Jan 7, 2005 - 3:40 AM
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i just call it a bent rim


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post Jan 7, 2005 - 7:09 AM
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Here we call speed bumps - "lying policeman"
It a pleasure to say, and even a greater pleasure to go over biggrin.gif biggrin.gif biggrin.gif
post Jan 7, 2005 - 7:15 AM
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popstar



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RZ

it more likly to be a p#$% and fallen over policeman over here wink.gif

there only fun when you know thier there, and our shocks are all ok smile.gif

i hit one the other night out our way mate (the road by the metro) thats on a corner and had a pot hole on the outher side that wasn't fun frown.gif


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post Jan 10, 2005 - 12:08 PM
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QUOTE(WannabeGT4 @ Jan 6, 2005 - 4:27 PM)
QUOTE(Jehuty @ Jan 6, 2005 - 3:21 PM)
1. Turbines are spun be HEAT. That's why turbos are mated right up to manifolds. Putting the turbo way back there looks like a good way to shed alot of heat....
[right][snapback]230750[/snapback][/right]


You sure about that?
[right][snapback]230755[/snapback][/right]


Altho a turbine wheel looks like a "pinwheel" or a "fan", it is a common miconception that its actually designed to work with exhaust pulses hitting the vanes. While exhaust pulses pushing the vanes soes come into play as a sort of secondary order force, turbines really are powered by heat.

Thats why if you look at the exit of a turbo manifold, the ports are pretty small. This would seem to go against the "less backpressure is better" rull for turbo cars, but that adviceonly applies to exhaust after the turbine. Forcing the fresh exhaust gasses thru a small space makes them hotter, which means they have more energy. Once the gasses enter the turbine housing, they expand into the larger spce, and dissapate heat. Again, the turbine wheel is not a "waterwheel" design. That is to say, it's not desigened to catch pulses around it's circumfrence. It's designed to harness the expansion of gasses and therefore the dissapation of heat.
post Jan 10, 2005 - 12:15 PM
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shid



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QUOTE(Jehuty @ Jan 10, 2005 - 5:08 PM)
QUOTE(WannabeGT4 @ Jan 6, 2005 - 4:27 PM)
QUOTE(Jehuty @ Jan 6, 2005 - 3:21 PM)
1. Turbines are spun be HEAT. That's why turbos are mated right up to manifolds. Putting the turbo way back there looks like a good way to shed alot of heat....
[right][snapback]230750[/snapback][/right]


You sure about that?
[right][snapback]230755[/snapback][/right]


Altho a turbine wheel looks like a "pinwheel" or a "fan", it is a common miconception that its actually designed to work with exhaust pulses hitting the vanes. While exhaust pulses pushing the vanes soes come into play as a sort of secondary order force, turbines really are powered by heat.

Thats why if you look at the exit of a turbo manifold, the ports are pretty small. This would seem to go against the "less backpressure is better" rull for turbo cars, but that adviceonly applies to exhaust after the turbine. Forcing the fresh exhaust gasses thru a small space makes them hotter, which means they have more energy. Once the gasses enter the turbine housing, they expand into the larger spce, and dissapate heat. Again, the turbine wheel is not a "waterwheel" design. That is to say, it's not desigened to catch pulses around it's circumfrence. It's designed to harness the expansion of gasses and therefore the dissapation of heat.
[right][snapback]232013[/snapback][/right]


Thats incorrect. Forcing the gasses through a small space doesn't make them any hotter, but it raises the pressure of air hitting the turbine. The turbine wheel is a waterwheel design, it does catch gas and thats what spins the turbine- it catches gas by the expansion of the heat from the engine which then forced into a smaller opening raising the pressure the force by which the turbine spins.

The reason the manifolds aren't 3 inches big is not because backpressure is good before the turbine, it's to limit and focus the amount of surface space of the air particles hitting the turbine. if the manifold is too big pressure across the entire fan drops, creating a longer spool time and a less efficient turbo.
post Jan 10, 2005 - 12:33 PM
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WannabeGT4



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QUOTE(Jehuty @ Jan 10, 2005 - 11:08 AM)
QUOTE(WannabeGT4 @ Jan 6, 2005 - 4:27 PM)
QUOTE(Jehuty @ Jan 6, 2005 - 3:21 PM)
1. Turbines are spun be HEAT. That's why turbos are mated right up to manifolds. Putting the turbo way back there looks like a good way to shed alot of heat....
[right][snapback]230750[/snapback][/right]


You sure about that?
[right][snapback]230755[/snapback][/right]


Altho a turbine wheel looks like a "pinwheel" or a "fan", it is a common miconception that its actually designed to work with exhaust pulses hitting the vanes. While exhaust pulses pushing the vanes soes come into play as a sort of secondary order force, turbines really are powered by heat.

Thats why if you look at the exit of a turbo manifold, the ports are pretty small. This would seem to go against the "less backpressure is better" rull for turbo cars, but that adviceonly applies to exhaust after the turbine. Forcing the fresh exhaust gasses thru a small space makes them hotter, which means they have more energy. Once the gasses enter the turbine housing, they expand into the larger spce, and dissapate heat. Again, the turbine wheel is not a "waterwheel" design. That is to say, it's not desigened to catch pulses around it's circumfrence. It's designed to harness the expansion of gasses and therefore the dissapation of heat.
[right][snapback]232013[/snapback][/right]


Ok So if I stick my turbo in an oven I'm going to be making boost? Heat being the main factor in making the turbo spin doesn't make any sense.


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post Jan 10, 2005 - 12:42 PM
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No, heat still IS the main factor to turbo spool. Without heat air expanding, you would never spool up or suck in air; because it'd always be at the same pressure. You'd suck in cool air, and just as much cool air would "push" the turbine. it doesn't work.
post Jan 10, 2005 - 12:49 PM
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QUOTE(WannabeGT4 @ Jan 10, 2005 - 12:33 PM)


Ok So if I stick my turbo in an oven I'm going to be making boost? Heat being the main factor in making the turbo spin doesn't make any sense.
[right][snapback]232018[/snapback][/right]



Haha, not quite! But if you where to dissapate heat from your pressurized exaust gasses by say... running them down the length of your car's underbody where cold air rushes by... they would remain pressurized, but not have as much of the energy to expand, dissapate, and spin the turbine as would hot gasses.

Of course, according to the Ideal Gas Law, we could be arguing semantics here, as there is a direct relation between pressure and heat. However that does not make my initial statement that turbines are driven by heat any less true. Nor does it change the fact that turbine performance would suffer if the exhausts gasses where cooled before reaching the turbine.
post Jan 10, 2005 - 12:51 PM
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shid



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QUOTE(Jehuty @ Jan 10, 2005 - 5:49 PM)
QUOTE(WannabeGT4 @ Jan 10, 2005 - 12:33 PM)


Ok So if I stick my turbo in an oven I'm going to be making boost? Heat being the main factor in making the turbo spin doesn't make any sense.
[right][snapback]232018[/snapback][/right]



Haha, not quite! But if you where to dissapate heat from your pressurized exaust gasses by say... running them down the length of your car's underbody where cold air rushes by... they would remain pressurized, but not have as much of the energy to expand, dissapate, and spin the turbine as would hot gasses.

Of course, according to the Ideal Gas Law, we could be arguing semantics here, as there is a direct relation between pressure and heat. However that does not make my initial statement that turbines are driven by heat any less true. Nor does it change the fact that turbine performance would suffer if the exhausts gasses where cooled before reaching the turbine.
[right][snapback]232022[/snapback][/right]


Your arguments are true, but how you arrived there is false.
post Jan 10, 2005 - 12:59 PM
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QUOTE(shid @ Jan 10, 2005 - 12:51 PM)


Your arguments are true, but how you arrived there is false.
[right][snapback]232024[/snapback][/right]


If you are reffering to the part about the outlets of the turbo manifold, then it's down to heat and pressure not being completly interchangable in that part of the turbo system. However, different manifold/turbine housings have been designed to emphasize either pressure, heat, or both. Is that the part that could be considered false or am I lost here?
post Jan 10, 2005 - 1:08 PM
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shid



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A turbo works almost exactly like a gas turbine engine (Link: http://travel.howstuffworks.com/turbine.htm )

and here's how turbochargers work:

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

because heated gases take up more space than cool gases; you are correct in saying without heat, the gasses would cool and take up less space- less pressure. However, you are incorrect in saying that the air does not move the turbine like a waterwheel- it is exactly like that.
post Jan 10, 2005 - 1:18 PM
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Jehuty

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QUOTE(shid @ Jan 10, 2005 - 1:08 PM)
A turbo works almost exactly like a gas turbine engine (Link: http://travel.howstuffworks.com/turbine.htm )

and here's how turbochargers work:

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

because heated gases take up more space than cool gases; you are correct in saying without heat, the gasses would cool and take up less space- less pressure. However, you are incorrect in saying that the air does not move the turbine like a waterwheel- it is exactly like that.
[right][snapback]232031[/snapback][/right]



Oh, I see. I was just trying to illustrate the difference between the way many people think a turbine works and the way it acutally does. That is, the picture many (if not most) people get in their head is that of the exhaust gasses "blowing" the turbine wheel. Hmmm, even that description can be ambiguous. Anyhow, yeah it's hard to clearly converse about. But I think we're on the same page. I hope I didn't make it more confusing than it needed to be by trying to explain myself.
post Jan 10, 2005 - 1:26 PM
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shid



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but exhaust gases DO blow the wheel.
post Jan 10, 2005 - 2:00 PM
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QUOTE(shid @ Jan 10, 2005 - 12:26 PM)
but exhaust gases DO blow the wheel.
[right][snapback]232036[/snapback][/right]


LOL That's what I was trying to say.


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post Jan 10, 2005 - 4:35 PM
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Jehuty

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QUOTE(Jehuty @ Jan 10, 2005 - 1:18 PM)
... exhaust gasses "blowing" the turbine wheel.  Hmmm, even that description can be ambiguous...
[right][snapback]232035[/snapback][/right]


I'm going to run out of ways to say this. I'm trying to point out the distiction between flowing gasses simply pushing the turbine around, and energy (heat) being reclaimed by the turbine wheel. And while you could say that flowing gasses do indeed simply push the turbine around, I think it's worth making the distinction.

And after all this, bleading the heat from the exhaust before it reaches the turbine still hurts the performance of the turbine. Re-interpretation of my admittedly gray-area language doesn't change that.

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