idiotic question time about intercoolers.....
12 January 2007, 12:03 PM
#31
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its totally clear to me now.
Exaust gasses come out of the block, and go into the turbo on the way to the exaust system/cat/back box and eventually the sky. When they pass through the turbo, the gasses spin the turbo, which in turn pressurizes air from the intake when that goes intot he turbo. It comes out of the turbo pressurized into the intercooler where it is cooled, on the way to the throttle body/inlet manifold/engine, where it produce 12 million BHP and shooots you to the moon.
Bongo
Exaust gasses come out of the block, and go into the turbo on the way to the exaust system/cat/back box and eventually the sky. When they pass through the turbo, the gasses spin the turbo, which in turn pressurizes air from the intake when that goes intot he turbo. It comes out of the turbo pressurized into the intercooler where it is cooled, on the way to the throttle body/inlet manifold/engine, where it produce 12 million BHP and shooots you to the moon.
Bongo
12 January 2007, 12:29 PM
#33
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Andy I'm 90% sure you are wrong 
The intake system on the Impreza is plumbed into the turbo and there is air filtration on the intake system. Exhaust gases drive the turbo as we all know. The exhaust gases don't mix with the intake gases. The exhaust gases push one end of the turbo to make the other end suck (if you like). I'm pretty sure at low RPM the turbo is still spinning with the flow of air through both ends - it's just not spinning fast enough to generate a build up of air trying to get into the engine (boost). Proof of this is when you switch off from idle you can hear the turbo spinning down.
On boost the turbo sucks air through whatever air filtration you have and then tries to force feed it through the throttle body via the intercooler/chargecooler.
The intake system on the Impreza is plumbed into the turbo and there is air filtration on the intake system. Exhaust gases drive the turbo as we all know. The exhaust gases don't mix with the intake gases. The exhaust gases push one end of the turbo to make the other end suck (if you like). I'm pretty sure at low RPM the turbo is still spinning with the flow of air through both ends - it's just not spinning fast enough to generate a build up of air trying to get into the engine (boost). Proof of this is when you switch off from idle you can hear the turbo spinning down.On boost the turbo sucks air through whatever air filtration you have and then tries to force feed it through the throttle body via the intercooler/chargecooler.
So did we decided that the exhaust gases are expelled after spinning the turbo and go back out the exhaust after that ?
12 January 2007, 12:45 PM
#34
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Aren't they basically identical, except superchargers don't intercept the exaust system in order to get the gases to spin it, as they spin constantly from some kind of belt from connected to the crankshaft??? Or a belt from somewhere...
bongo
bongo
12 January 2007, 12:57 PM
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(Jee, that's brave of me to "chip in" again !)
I shall now beat the retreat to "muppets" !
12 January 2007, 01:02 PM
#36
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i've decided i'm not listening to anything you say anymore . get back on your cannondale and go ride the scottish hills!
lol, only kiddin, i might listen, a bit!
Bongo
. get back on your cannondale and go ride the scottish hills!lol, only kiddin, i might listen, a bit!
Bongo
12 January 2007, 02:03 PM
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OK, Started thinking about the workings of an engine and stumbled across this query... What exactly does an intercooler do???
You have a radiator, which contains water which is cooled by the air flowing through it, then the water keeps the engine cool enough right...
Then the intercooler is also filled with water yeah?!, so that water is cooled by the air coming into the scoop, so what does this cooled water cool?! Does it cool the aire that the air intake has taken in, before it gets any further??!?!
It's baffling me at the minute!! Apologies for such a newb question, but then, i am a 'good car newb'!!
Bongo!
You have a radiator, which contains water which is cooled by the air flowing through it, then the water keeps the engine cool enough right...
Then the intercooler is also filled with water yeah?!, so that water is cooled by the air coming into the scoop, so what does this cooled water cool?! Does it cool the aire that the air intake has taken in, before it gets any further??!?!
It's baffling me at the minute!! Apologies for such a newb question, but then, i am a 'good car newb'!!
Bongo!
12 January 2007, 02:11 PM
#39
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How about that for a tongue twister.
(i've onlt recently learnt myself)
12 January 2007, 02:50 PM
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12 January 2007, 06:09 PM
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Further to the other diagrams, here's another with some of the intake detail included...
(taken from this very site on another thread somewhere).
(taken from this very site on another thread somewhere).
12 January 2007, 11:15 PM
#42
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3 good diagrams there.
Turbos are good eh?
Why not have a small one and a big one though? Is it purely because of fuel economy? Would be a lot more responsive though.
Where does the dump valve fit into it as well please.
How does the dump valve know you have come off the throttle? is it because the exhaust gases stop spining the turbo?
Turbos are good eh?
Why not have a small one and a big one though? Is it purely because of fuel economy? Would be a lot more responsive though.
Where does the dump valve fit into it as well please.
How does the dump valve know you have come off the throttle? is it because the exhaust gases stop spining the turbo?
12 January 2007, 11:34 PM
#43
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3 good diagrams there.
Turbos are good eh?
Why not have a small one and a big one though? Is it purely because of fuel economy? Would be a lot more responsive though.
Where does the dump valve fit into it as well please.
How does the dump valve know you have come off the throttle? is it because the exhaust gases stop spining the turbo?
Turbos are good eh?
Why not have a small one and a big one though? Is it purely because of fuel economy? Would be a lot more responsive though.
Where does the dump valve fit into it as well please.
How does the dump valve know you have come off the throttle? is it because the exhaust gases stop spining the turbo?
Twin turbo set up :-
Don't forget the wastegate.Turbochargers have a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses the boost pressure. If the pressure gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down.
Mark
Last edited by FLAT ERIC; 12 January 2007 at 11:45 PM.
13 January 2007, 10:31 AM
#44
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Good thread. Fair play for people admitting they don't know. Shame on the mockers for extracting the michael.
> Where does the dump valve fit into it as well please.
The dump valve is connected to the pressurised sytem between the turbo compressor outlet and the engine, physically it's connected to the pressurised side of the intercooler. When the pressure in this bit gets too high the dump valve opens and lets some of this pressure out.
> How does the dump valve know you have come off the throttle? is it
> because the exhaust gases stop spining the turbo?
When you come off the throttle the turbo keeps sending compressed air to the engine for a short time but as the engine has stopped taking the air, throttle closed, there's nowhere for this air to go so the pressure rises. The dump valve sees the pressure rising and opens to allow the pressure to fall. In the longer term as you say lack of exhaust gas stops powering the turbo so the dump valve can close again.
The lancia delta group B rally car had a supercharger for low down grunt and a huge turbo for peak power. The supercharger drive had a clutch so it was disengaged as revs rose. That had complicated plumbing.
Out of interest they're both technically superchargers because they increase pressure. What we normally call a supercharger is a mechanically driven supercharger, what we normally call a turbocharger is an exhaust gas powered turbine driven supercharger.
> Where does the dump valve fit into it as well please.
The dump valve is connected to the pressurised sytem between the turbo compressor outlet and the engine, physically it's connected to the pressurised side of the intercooler. When the pressure in this bit gets too high the dump valve opens and lets some of this pressure out.
> How does the dump valve know you have come off the throttle? is it
> because the exhaust gases stop spining the turbo?
When you come off the throttle the turbo keeps sending compressed air to the engine for a short time but as the engine has stopped taking the air, throttle closed, there's nowhere for this air to go so the pressure rises. The dump valve sees the pressure rising and opens to allow the pressure to fall. In the longer term as you say lack of exhaust gas stops powering the turbo so the dump valve can close again.
The lancia delta group B rally car had a supercharger for low down grunt and a huge turbo for peak power. The supercharger drive had a clutch so it was disengaged as revs rose. That had complicated plumbing.
Out of interest they're both technically superchargers because they increase pressure. What we normally call a supercharger is a mechanically driven supercharger, what we normally call a turbocharger is an exhaust gas powered turbine driven supercharger.
13 January 2007, 11:22 AM
#46
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Yep, will head up into the Pentlands on my Cannondale today, despite the wind and rain !
13 January 2007, 11:50 AM
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13 January 2007, 11:52 AM
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13 January 2007, 12:05 PM
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13 January 2007, 12:39 PM
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A 'twin scroll' turbocharger has two seperate inlets (and obviously uses a different manifold). The purpose is to seperate the pulses and to stop them from interfering with each other. This is easier said than done and actually making it work is quite a feat in itself.
13 January 2007, 12:55 PM
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13 January 2007, 12:57 PM
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I still maintain that plumbing the air inlet across the air con would generate more power in the right set up, than would be drawn from the engine to power the air-on.
13 January 2007, 01:00 PM
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13 January 2007, 01:06 PM
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Not really, PM can never be achieved on a fuel driven device, can it?
I mean in certain circumstances.....hot weather for instance, when you may have the air-con on anyway. What does the air-con sap?....5HP?
Sureley the right set up, and with air at what 10DEG, would produce a larger gain that 5HP?
What does your average intercooler drop the air temp by?
I mean in certain circumstances.....hot weather for instance, when you may have the air-con on anyway. What does the air-con sap?....5HP?
Sureley the right set up, and with air at what 10DEG, would produce a larger gain that 5HP?
What does your average intercooler drop the air temp by?
13 January 2007, 01:24 PM
#56
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ROFL there's some cracking laughs I've had on this thread, but in the interests of education, here's a few titbits for you:
All intercoolers are chargecoolers. Nowadays it has come to be known that when you say intercooler you mean an air-air (pressurised charge air inside cooled by atmospheric air flowing across it outside) and when you say chargecooler this means a water-air (like a water radiator inside out - pressurised charge air inside cooled by water flowing across the outside, although this is also all contained in a waterproof box). Both systems have their pros and cons which I won't go into now.
Similarly, all turbochargers are actually superchargers. In everyday use though, the term supercharger means the compressor is driven off a belt or gears, and the term turbocharger means it is driven off a turbine powered by exhaust gases. Again, there are many pros and cons to each.
As far as the aircon idea goes, in time, every car enthusiasts' forum in the world has mulled over this concept. The fundamental reason why it wouldn't work is down to the airflow required by an engine. When an aircon system simply has to knock ten degrees off the temperature inside the cabin of a car, in maybe a minute, it's done its job. Its capacity to take say 100 degrees of heat out of the charge air continuously is virtually zero. It's like leaving a few ice cubes in the middle of your living room and expecting the room to become chilly.
The amount of energy that would need to be put into an aircon system to get it to extract the charge heat you want it to would make the whole exercise pointless. Far better to use the forward motion of the car which can supply huge amounts of cooling airflow over your intercooler fins or chargecooler's rad.
All intercoolers are chargecoolers. Nowadays it has come to be known that when you say intercooler you mean an air-air (pressurised charge air inside cooled by atmospheric air flowing across it outside) and when you say chargecooler this means a water-air (like a water radiator inside out - pressurised charge air inside cooled by water flowing across the outside, although this is also all contained in a waterproof box). Both systems have their pros and cons which I won't go into now.
Similarly, all turbochargers are actually superchargers. In everyday use though, the term supercharger means the compressor is driven off a belt or gears, and the term turbocharger means it is driven off a turbine powered by exhaust gases. Again, there are many pros and cons to each.
As far as the aircon idea goes, in time, every car enthusiasts' forum in the world has mulled over this concept. The fundamental reason why it wouldn't work is down to the airflow required by an engine. When an aircon system simply has to knock ten degrees off the temperature inside the cabin of a car, in maybe a minute, it's done its job. Its capacity to take say 100 degrees of heat out of the charge air continuously is virtually zero. It's like leaving a few ice cubes in the middle of your living room and expecting the room to become chilly.
The amount of energy that would need to be put into an aircon system to get it to extract the charge heat you want it to would make the whole exercise pointless. Far better to use the forward motion of the car which can supply huge amounts of cooling airflow over your intercooler fins or chargecooler's rad.
13 January 2007, 01:31 PM
#57
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Oh yes...twin scroll. Basically the most efficient way for a turbocharger to work is with no onward exhaust system connected to the outlet of the turbine and exhaust pulses from the engine reaching the inlet of the turbine at evenly spaced intervals. The first idea is pretty much impossible in a practical sense, but it explains why high power systems tend to run short, big bore exhausts. The regularity of the exhaust pulses relies on the layout of the exhaust manifold, number of cylinders etc etc. but twin scroll is one workaround to try and drive the turbine more efficiently than would otherwise be possible with the Subaru flat four arrangement. The characteristic off-beat sound of the Subaru engine is down to the exhaust pulses being 'uneven'.
13 January 2007, 04:53 PM
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Good thread. Fair play for people admitting they don't know. Shame on the mockers for extracting the michael.
> Where does the dump valve fit into it as well please.
The dump valve is connected to the pressurised sytem between the turbo compressor outlet and the engine, physically it's connected to the pressurised side of the intercooler. When the pressure in this bit gets too high the dump valve opens and lets some of this pressure out.
> How does the dump valve know you have come off the throttle? is it
> because the exhaust gases stop spining the turbo?
When you come off the throttle the turbo keeps sending compressed air to the engine for a short time but as the engine has stopped taking the air, throttle closed, there's nowhere for this air to go so the pressure rises. The dump valve sees the pressure rising and opens to allow the pressure to fall. In the longer term as you say lack of exhaust gas stops powering the turbo so the dump valve can close again.
The lancia delta group B rally car had a supercharger for low down grunt and a huge turbo for peak power. The supercharger drive had a clutch so it was disengaged as revs rose. That had complicated plumbing.
Out of interest they're both technically superchargers because they increase pressure. What we normally call a supercharger is a mechanically driven supercharger, what we normally call a turbocharger is an exhaust gas powered turbine driven supercharger.
> Where does the dump valve fit into it as well please.
The dump valve is connected to the pressurised sytem between the turbo compressor outlet and the engine, physically it's connected to the pressurised side of the intercooler. When the pressure in this bit gets too high the dump valve opens and lets some of this pressure out.
> How does the dump valve know you have come off the throttle? is it
> because the exhaust gases stop spining the turbo?
When you come off the throttle the turbo keeps sending compressed air to the engine for a short time but as the engine has stopped taking the air, throttle closed, there's nowhere for this air to go so the pressure rises. The dump valve sees the pressure rising and opens to allow the pressure to fall. In the longer term as you say lack of exhaust gas stops powering the turbo so the dump valve can close again.
The lancia delta group B rally car had a supercharger for low down grunt and a huge turbo for peak power. The supercharger drive had a clutch so it was disengaged as revs rose. That had complicated plumbing.
Out of interest they're both technically superchargers because they increase pressure. What we normally call a supercharger is a mechanically driven supercharger, what we normally call a turbocharger is an exhaust gas powered turbine driven supercharger.
ALSO, thanks FLAT ERIC.
... do both the 2 turbo's? continue to spin?
or does the smaller spin then when the big takes over does the smaller one close a valve and just lets exhaust gases go to the bogger one?
and, is the front one the smaller one or the back one?
or are they 2 turbo's smaller working simultainiously?
cheers
