Joined
·
580 Posts
What exactly causes the car to suck up air ??
What sucks up the air ??
1 - 20 of 21 Posts
well in a turbo engine its the turbo being driven by the engine, it has an impeller, i think its called, which when spinning creates a vacuum , the vacuum air is being fed from the air cleaner then gets compressed by the turbo, which then goes through the intercooler to lose some heat, and finally into the engine, in a normally aspirated car its the action of the piston on the downward stroke which creates a vacuum thus sucking up air through the air cleaner, hope you understood this, because i dont
]
]What do you mean buy suck up air - the engine? or aerodynamics?
Engine is simple, it's a four stroke - which means the first stroke (journey of the piston) is to suck air in through the inlet valve via the manifold and air intake. It's the same principle in a turbo engine only the air coming in to the engine passes through the turbo which compresses that air.
Many think it's the turbo that causes the suck - it's not. The suck is still caused by the combined action of the piston moving downwards and the inlet valve opening.
There is a fab website somewhere with it all explained in animated form, some more knowledgable members might know where to find it.
edit: found it!Main pagehttp://auto.howstuffworks.com/engine.htm
Animated engine http://auto.howstuffworks.com/engine3.htm
How a Turbo works http://auto.howstuffworks.com/turbo4.htm
Aerodynamics are a black art in themselves and I really don't know enough to explain.
Engine is simple, it's a four stroke - which means the first stroke (journey of the piston) is to suck air in through the inlet valve via the manifold and air intake. It's the same principle in a turbo engine only the air coming in to the engine passes through the turbo which compresses that air.
Many think it's the turbo that causes the suck - it's not. The suck is still caused by the combined action of the piston moving downwards and the inlet valve opening.
There is a fab website somewhere with it all explained in animated form, some more knowledgable members might know where to find it.
edit: found it!Main pagehttp://auto.howstuffworks.com/engine.htm
Animated engine http://auto.howstuffworks.com/engine3.htm
How a Turbo works http://auto.howstuffworks.com/turbo4.htm
Aerodynamics are a black art in themselves and I really don't know enough to explain.
Joined
·
796 Posts
with aerodynamics its similar to how a wing works presumably.
due to the shape of the wing the air travelling over the top of the wing has to travel further in the same amount of time as that below the wing (ie its moving faster), thus decreasing the pressure above the wing and creating "lift"
blag []
due to the shape of the wing the air travelling over the top of the wing has to travel further in the same amount of time as that below the wing (ie its moving faster), thus decreasing the pressure above the wing and creating "lift"
blag [
]You're not wrong there. It's the correllation between drag and lift/downforce that gets complicated.
You can have downforce which gives horrendous drag thus you need massive power to make it work and correspondingly you can do a simple thing which will give much greater efficiency.
I remember seeing a real nerdy article years ago where they tested the drag from things like roof racks and open windows to see what difference it made. Quite suprising how much an open window can affect fuel consumption as the engine has to operate harder to travel at the same speed.
The same with loads of spoliers on the market - very few (if any!) have been developed in a wind tunnel and they just create drag which effectively slows the car down..... Hence why these barryboys motors are so slow, it's not the ton of filler in the car, they have to push the equivalent of a brick wall round!
You can have downforce which gives horrendous drag thus you need massive power to make it work and correspondingly you can do a simple thing which will give much greater efficiency.
I remember seeing a real nerdy article years ago where they tested the drag from things like roof racks and open windows to see what difference it made. Quite suprising how much an open window can affect fuel consumption as the engine has to operate harder to travel at the same speed.
The same with loads of spoliers on the market - very few (if any!) have been developed in a wind tunnel and they just create drag which effectively slows the car down..... Hence why these barryboys motors are so slow, it's not the ton of filler in the car, they have to push the equivalent of a brick wall round!
Joined
·
1,962 Posts
Eh excuse me I beg to differ, the turbo does in fact push the air into the cylinders on a turbo car when it is on boost. When not on boost such as at cruise speed on the Mway, the air is drawn in by the vacume cause by the downwards movement of the piston.
So in a 1.8T the air is drawn in by the pistons until the car is on boost when the turbo draws in the air compresses it and shoves it into the cylinder.
If you run a boost gauge is it quite interesting to compare the boost against vacume state of the engine.
Of course all IMHO.
So in a 1.8T the air is drawn in by the pistons until the car is on boost when the turbo draws in the air compresses it and shoves it into the cylinder.
If you run a boost gauge is it quite interesting to compare the boost against vacume state of the engine.
Of course all IMHO.
Joined
·
580 Posts
THing is apparently my air mass volume taken in readings are low for full throttle 200.5 kg/h several air mass meters have been tried with no joy so im wondering what else along the line could be causing the car to take in less air.
Joined
·
796 Posts
this is a very intellectual thread....!!!
from the looks of baz's second post we're all barking up the wrong tree tho!! lol!
from the looks of baz's second post we're all barking up the wrong tree tho!! lol!
Quote: posted by Bazrazmataz on 09/12/2004 13:23:01
THing is apparently my air mass volume taken in readings are low for full throttle 200.5 kg/h several air mass meters have been tried with no joy so im wondering what else along the line could be causing the car to take in less air.
less[?]
i would say thats pretty good on a k-03s 1.8t, normal is about 180g/s
THing is apparently my air mass volume taken in readings are low for full throttle 200.5 kg/h several air mass meters have been tried with no joy so im wondering what else along the line could be causing the car to take in less air.
less[?]
i would say thats pretty good on a k-03s 1.8t, normal is about 180g/s
Joined
·
1,962 Posts
A few curveball suggestions off the top of my head :-
Wastegate actuator on the Turbo they did have some issues where the rod came adrift from the diaphram.
Cat problem so not flowing enough exhaust.
Loom problem back to the ECU from the MAF - but I'd expect fuel trim issues as well.
Was the MAF housing changed with the MAF sensor or just the sensor bit changed ? I take it you have tried it with the stock airbox back on ?
Fuel pump but again I'd expect that to be spotted on a datablock log as the fuel trim would be out.
Wastegate actuator on the Turbo they did have some issues where the rod came adrift from the diaphram.
Cat problem so not flowing enough exhaust.
Loom problem back to the ECU from the MAF - but I'd expect fuel trim issues as well.
Was the MAF housing changed with the MAF sensor or just the sensor bit changed ? I take it you have tried it with the stock airbox back on ?
Fuel pump but again I'd expect that to be spotted on a datablock log as the fuel trim would be out.
Quote: posted by Gti Jazz Blue on 09/12/2004 13:21:56
...the turbo does in fact push the air into the cylinders on a turbo car when it is on boost....
We differ there then. The air is compressed by the turbo, not pushed into the cylinder. It's the combined action of the inlet valve opening and the piston falling that sucks the compressed air (which by this stage is known as an inlet charge as it will be mixed with fuel spray from the injectors) into the cylinder. Don't forget the turbo is spinning all the time thus keeping the air compressed in the manifold, it doesn't spin/spool up each time an inlet valve opens. Remember also a turbocharged engine will still function even if the turbo isn't working.
...the turbo does in fact push the air into the cylinders on a turbo car when it is on boost....
We differ there then. The air is compressed by the turbo, not pushed into the cylinder. It's the combined action of the inlet valve opening and the piston falling that sucks the compressed air (which by this stage is known as an inlet charge as it will be mixed with fuel spray from the injectors) into the cylinder. Don't forget the turbo is spinning all the time thus keeping the air compressed in the manifold, it doesn't spin/spool up each time an inlet valve opens. Remember also a turbocharged engine will still function even if the turbo isn't working.
Joined
·
1,962 Posts
It will definately run without the turbo as I stated a lot of the time it does as the inlet manifold is in a vacume state, so the piston is sucking the air in. If the inlet is in a positive air condition when the inlet valve to a cylinder is opened then surely physics dictates that the air is pushed into the cylinder as the manifold is in a possitive pressure state rather than atmospheric pressure.
But hey I'm open to be enlightened if I'm wrong, having said that I suppose that there would be a bit of either as the piston will be on a downstroke so sucking air but as the air is higher than ambient pressure i.e. boosted it will be pushed to a degree as well. Afterall if it was mearly sucked by the piston the turbo wouldn't make a jot of difference.
But hey I'm open to be enlightened if I'm wrong, having said that I suppose that there would be a bit of either as the piston will be on a downstroke so sucking air but as the air is higher than ambient pressure i.e. boosted it will be pushed to a degree as well. Afterall if it was mearly sucked by the piston the turbo wouldn't make a jot of difference.
I always think of it in terms of atmosphereic wieght. The air all the way up to the stratosphere weighs quite a bit - so when you create an absence of air by drawing a piston down or spinning a turbo the air is actually pushed in by all the air above it in the atmosphere. So no actual sucking going on at all - it's all pushing !
But you're right this isn't that actual answer to the question posted []
But you're right this isn't that actual answer to the question posted [
]Fine line really, I don't think you're wrong per se, remember too turbos are considered 'forced induction', more like we see it from different angles.
Yes there will be an element of push when the turbo is on boost. It's a bit chicken and egg, the turbo won't be on boost unless the engine is accelerating, think of an engine on tick over, the turbo is spinning, but not boosting/pushing/compressing to any great degree. The engine is still running, ergo the sucking action is from the piston strokes as already described. Things change when accelerating as the sequence of events drives up the boost pressure, inlet charge compression etc etc. Please also remember it's a combination of factors including the exhaust stroke causing an element of vacuum in the cylinder, which complements the action of the falling piston sucking in the inlet charge.
There's so many other elements to think about, the turbo does make a difference because the piston is sucking in air which because it's compressed is also more dense which causes better burn, it's probably cooler too which again lifts the burning capability.
I can't verbalise the way that site does, so for a full explanation much better than I can, have a look at the how it works stuff.
Yes there will be an element of push when the turbo is on boost. It's a bit chicken and egg, the turbo won't be on boost unless the engine is accelerating, think of an engine on tick over, the turbo is spinning, but not boosting/pushing/compressing to any great degree. The engine is still running, ergo the sucking action is from the piston strokes as already described. Things change when accelerating as the sequence of events drives up the boost pressure, inlet charge compression etc etc. Please also remember it's a combination of factors including the exhaust stroke causing an element of vacuum in the cylinder, which complements the action of the falling piston sucking in the inlet charge.
There's so many other elements to think about, the turbo does make a difference because the piston is sucking in air which because it's compressed is also more dense which causes better burn, it's probably cooler too which again lifts the burning capability.
I can't verbalise the way that site does, so for a full explanation much better than I can, have a look at the how it works stuff.
Joined
·
580 Posts
Based on what Saul states if its 180 g/s then that would be 648 kg/h so thats way off what im getting ! I could be wrong my maths arnt that good.
Joined
·
580 Posts
Any opionions on the topic ?
Joined
·
580 Posts
Well its a carbonio air intake it was recently put on
1 - 20 of 21 Posts
