bbunting
BB you left this one out.
I'm going to sit back and enjoy this! :doh:
opcorn: opcorn: opcorn: opcorn: Where is Charles
They aren't a function of each other first of all. Air is air. in thermodynamics we know this:
Density=mass/volume
That is simple.
LIke I said pressure is a reaction of this equation, not an action.
You have to start thinking temperatures and not pressures.
Pressure is a force only, a reaction to an action, not the other way around boost doesn't come before mass air is introduced into the turbo and the boundary it is pressurizing.
Think of it like this.
When you bench press weight at the gym, you have the weights(volume) beacuase they don't change. You have the muscle of the arm(air mass). And the boost pressure is the amount of force applied to move the weigths with the arm. A bigger arm will take less force to move the weight vs. a weeny arm who can barely move the weight or not even at all. THis is because their is more connective tissue(air mass) to support the weigths in the first place. You have a ratio of mass vs a fixed weight by a pressure or force applied to push it. THis outcome would be the (density).
The more density prevalent before the intake valve, the more horspower can be supported.
Think of the tiny arm pushing and pushing harder to force that weight up. It may get 1 or 2 reps and become exhausted, heated and tired, while the huge muscle arm is pushing and pushing, never getting tired and barely breaking a sweat.
THis can all be summed up using basic science. THis isn't anything exotic here, you just have to know how air acts and reacts to thermodynamic law.
Why is colder air more dense then hot air? No more pressure has been applied then atmospheric? See, it has nothing to do with pressure, that is an independednt phenomenoa of turbocharging. All pressure is not a weight, but a measurement of restriction. You have 80lbs sitting on the manifold. It could have 10lbs of air in it or 50lbs of air residing. Has nothing to do with pressure, it has everything to do with the mass of the air. Look up thermal compression.
Density=mass/volume
That is simple.
LIke I said pressure is a reaction of this equation, not an action.
You have to start thinking temperatures and not pressures.
Pressure is a force only, a reaction to an action, not the other way around boost doesn't come before mass air is introduced into the turbo and the boundary it is pressurizing.
Think of it like this.
When you bench press weight at the gym, you have the weights(volume) beacuase they don't change. You have the muscle of the arm(air mass). And the boost pressure is the amount of force applied to move the weigths with the arm. A bigger arm will take less force to move the weight vs. a weeny arm who can barely move the weight or not even at all. THis is because their is more connective tissue(air mass) to support the weigths in the first place. You have a ratio of mass vs a fixed weight by a pressure or force applied to push it. THis outcome would be the (density).
The more density prevalent before the intake valve, the more horspower can be supported.
Think of the tiny arm pushing and pushing harder to force that weight up. It may get 1 or 2 reps and become exhausted, heated and tired, while the huge muscle arm is pushing and pushing, never getting tired and barely breaking a sweat.
THis can all be summed up using basic science. THis isn't anything exotic here, you just have to know how air acts and reacts to thermodynamic law.
Why is colder air more dense then hot air? No more pressure has been applied then atmospheric? See, it has nothing to do with pressure, that is an independednt phenomenoa of turbocharging. All pressure is not a weight, but a measurement of restriction. You have 80lbs sitting on the manifold. It could have 10lbs of air in it or 50lbs of air residing. Has nothing to do with pressure, it has everything to do with the mass of the air. Look up thermal compression.
Time to back up a little bit more, back to highschool chemistry (yuck). The Diesel engine is an internal combustion engine. This means you need fuel & oxygen. The equation will say that for XXX number of moecules of Diesel fuel, you need YYY number of oxygen molecules to get complete combustion (Let's ignore incomplete combustion for this thread).
Now, YYY number of oxygen molecules will always weigh a certain amount. Avogadro's number (6.0221415 × 10^23) and the atom mass determine what that weight is.
So to get complete combustion you will need YYY*AN pounds of oxygen (let's call it RRR) to get complete combustion.
Now the fun begins. Air (oxygen) is a gas, and therefore it is compressible. But, it will still weigh the same amount (same # of oxygen molecules). Temperature also plays a part in the equation: P(ressure)*V(olume)=n(# of moles)*R(Universal gas constant)*T(emperature). The only constants we have are n, R, and V. Hence boost pressure will go up as temperature increases.
So for the same # of pounds of air, the volume (cfm) will vary depending on pressure (boost) and temperature.
The temperature of the air can be reduced (decreasing boost, but not of weight (RRR) of the air) with a more efficient turbo, without decreasing any power! This is air density. The more air you pack in a single space without changing the temperature, the more dense it is.
The other way to increase air density is to increase the pressure with the same turbo. But, this increases temperature and you lose density.
So, boost and air density are not really seperate. Boost is the most common way to increase density, but not without drawbacks (heat).
Now, YYY number of oxygen molecules will always weigh a certain amount. Avogadro's number (6.0221415 × 10^23) and the atom mass determine what that weight is.
So to get complete combustion you will need YYY*AN pounds of oxygen (let's call it RRR) to get complete combustion.
Now the fun begins. Air (oxygen) is a gas, and therefore it is compressible. But, it will still weigh the same amount (same # of oxygen molecules). Temperature also plays a part in the equation: P(ressure)*V(olume)=n(# of moles)*R(Universal gas constant)*T(emperature). The only constants we have are n, R, and V. Hence boost pressure will go up as temperature increases.
So for the same # of pounds of air, the volume (cfm) will vary depending on pressure (boost) and temperature.
The temperature of the air can be reduced (decreasing boost, but not of weight (RRR) of the air) with a more efficient turbo, without decreasing any power! This is air density. The more air you pack in a single space without changing the temperature, the more dense it is.
The other way to increase air density is to increase the pressure with the same turbo. But, this increases temperature and you lose density.
So, boost and air density are not really seperate. Boost is the most common way to increase density, but not without drawbacks (heat).
Exactly the reason for intercoolers in the first place.
And water injection, and nitrous.
All accomplish the same thing , in different ways.
Cooling of the intake air , and introduction of more oxygen.
And water injection, and nitrous.
All accomplish the same thing , in different ways.
Cooling of the intake air , and introduction of more oxygen.
Yup. More air, less pressure, lower intake temps, higher density. Hate to say it, but why does banks make 1000hp on 36lbs of boost?
It's actually 4 stages if everythign I looked at in Bakersfield is hooked up and working.
There are 8 solenoids on that motor....4 purge and 4 for the motor.
There are 8 solenoids on that motor....4 purge and 4 for the motor.
I would have to say there's tons of restriction....from the bends in the system piping, the intercooler itself, the intake and specifcally the valves in the heads.
From the turbo outlet to the intake valve is nothing but 1 big restriction.
From the turbo outlet to the intake valve is nothing but 1 big restriction.
THe nitrous helps, anf in this case takes over for an intercooler, as it doesn't have one. The head work definately plays a key role, but I bet it starts making you think alittel bit about engine VE, as the turbo has no real effect , when it comes down to that.
This phrase is thrown around way too much.
If I keep the exact same turbo, CAC pipes, same intercooler, same manifolds, same heads/valves, etc, but change to slightly larger injectors, I'll get more boost. So does that mean that because I have more boost, I just added more restriction to my intake system?
As you can see, that phrase doesn't make sense. Boost is not a "measure of restriction". A rag in the intake is a restriction (lol sorry Andrew).
Yes. You havent added any more air. Restriction is a reaction to air mass delivery to a fixed boundary.
My specific point was directly related to adding more air. If I threw bigger injectors on my truck (I'm currently running stock injectors), then I would have enough fueling to drive the turbo to produce more boost than what I have currently. Right now I'm only putting out a max around 30 psi on the GTP38R, and it can efficiently handle more than that. Reaching 40 psi on the same turbo??? Yes, I would have more air, but it would not make sense to state that I have more restriction because my boost went up.
Let's say you have an air tank and air inside pressurized to 10 psi. Now you pump more air in untill you reach 20 psi. Does that mean there was more "restriction" added? Of course not. Simply put, there was more air mass introduced.
Again, it is a mis-statement to say that boost is a measure of restriction.
Why is the grass green? Why is the sky blue? Why are boobs good? How does the posi-trac rear on a Plymouth work?
Don't nobody know, it just does!
Don't nobody know, it just does!
That does it. I'm pulling the turbo, CAC and plumbing off the truck. It's obviously a waste of energy. I will gain torque with less lag and fuel mileage will go through the roof.
If I have understood everything I have learned about boost, and VE, is that, If your running 10lbs of boost with a turbo, and you change the heads and add more fuel now your boost is reading 6lbs of boost, you have just created more power with less heat due to more VE.
Now if you take that same 10lbs of boost you had originally, and now just give it more fuel to that, assuming the only change was the amount of exhaust powering the turbo, you will create more boost, but at the same time you are forcing more air at one time, which is going to yeild more power, but at the cost of higher heat.
Is this correct or no? Trying to learn.
Now if you take that same 10lbs of boost you had originally, and now just give it more fuel to that, assuming the only change was the amount of exhaust powering the turbo, you will create more boost, but at the same time you are forcing more air at one time, which is going to yeild more power, but at the cost of higher heat.
Is this correct or no? Trying to learn.
The wizardry behind turbocharging, and if you ask anyone who really knows what the heck they are doing, is, you want the highest amount of air charge density possible, delivered with the least amount of boost necessary, while the turbo spins as slow as it possibly needs to, while providing as much mass air as is physically possible all before the intake valve. That is all a turbo can do. Everything else is dependent on the engine. That is why I always ask people to divide the engine and the turbo charger systems apart and break them down individually. A well built turbo engine will take into account the turbocharger. A great turbocharger system will take into account the engine. A well balanced symbiotic relationship between both will provide the best results. Overcompensating on one end (ie: high boost) or the other will teeter the edge past efficiency, causing the engine at some point to fail or the turbo system to become compromised so that it is doing more harm than good.
Geez, all that reading and it still comes down to this. If you increase the pressure and the temp stays the same you have increased the density. Saying boost is separate from density is like saying torque is separate from HP.
You folks are killing me. Here is the definition:
From Wikipedia, the free encyclopedia
Volumetric efficiency in internal combustion engine design refers to the efficiency with which the engine can move the charge into and out of the cylinders. More correctly, volumetric efficiency is a ratio (or percentage) of what volume of fuel and air actually enters the cylinder during induction to the actual capacity of the cylinder under static conditions. Therefore, those engines that can create higher induction manifold pressures - above ambient - will have efficiencies greater than 100%. Volumetric efficiencies can be improved in a number of ways, but most notably the size of the valve openings compared to the volume of the cylinder and streamlining the ports. Engines with higher volumetric efficiency will generally be able to run at higher RPM and produce more overall power due to less parasitic power loss moving air in and out of the engine.
There are several standard ways to improve volumetric efficiency. A common approach for manufacturers is to use a larger valves or multiple valves. Larger valves increase flow but weigh more. Multi-valve engines combine two or more smaller valves with areas greater than a single, large valve while having less weight. Carefully streamlining the ports increases flow capability. This is referred to as Porting and is done with the aid of an air flow bench for testing.
Today, automobile engines typically have four valves per cylinder. Many high performance cars in the 1970s used carefully arranged air intakes and "tuned" exhaust systems to "push" air into and out of the cylinders, making use of the resonance of the system. Two-stroke engines take this concept even further with expansion chambers that returns the escaping air-fuel mixture back to the cylinder. A more modern technique, variable valve timing, attempts to address changes in volumetric efficiency with changes in RPM of the engine: at higher RPM the engine needs the valves open for a greater percentage of the cycle time to move the charge in and out of the engine.
Volumetric efficiencies above 100% can be reached by using forced induction such as supercharging or turbocharging.
More "radical" solutions include the sleeve valve design, in which the valves are replaced outright with a rotating sleeve around the piston, or alternately a rotating sleeve under the cylinder head. In this system the ports can be as large as necessary, up to that of the entire cylinder wall. However there is a practical upper limit due to the strength of the sleeve, at larger sizes the pressure inside the cylinder can "pop" the sleeve if the port is too large.
Volumetric Efficiency is frequently abbreviated as "VE" when discussing engine efficiency.
If you have a 1 liter flask at atmospheric pressure (~14.5psi) and you double the pressure in you 1 liter flask to 29psi or 2 atmospheres you have doubled the VE.
I think AirFlow may be wanting to describe fill efficiency of the cylinder. Because of valve overlap and remaining exhaust in the cylinder, you may never get 100% fill efficiency. You might get a 90% fill of 2, 3, or 4 atmospheres of air (i.e. 29, 43.5, or 58 psi). Guys got to get your terms correct when you start discussing this stuff. Been 32 years since I did my thermo courses, so don't make go back and break out my text books.
From Wikipedia, the free encyclopedia
Volumetric efficiency in internal combustion engine design refers to the efficiency with which the engine can move the charge into and out of the cylinders. More correctly, volumetric efficiency is a ratio (or percentage) of what volume of fuel and air actually enters the cylinder during induction to the actual capacity of the cylinder under static conditions. Therefore, those engines that can create higher induction manifold pressures - above ambient - will have efficiencies greater than 100%. Volumetric efficiencies can be improved in a number of ways, but most notably the size of the valve openings compared to the volume of the cylinder and streamlining the ports. Engines with higher volumetric efficiency will generally be able to run at higher RPM and produce more overall power due to less parasitic power loss moving air in and out of the engine.
There are several standard ways to improve volumetric efficiency. A common approach for manufacturers is to use a larger valves or multiple valves. Larger valves increase flow but weigh more. Multi-valve engines combine two or more smaller valves with areas greater than a single, large valve while having less weight. Carefully streamlining the ports increases flow capability. This is referred to as Porting and is done with the aid of an air flow bench for testing.
Today, automobile engines typically have four valves per cylinder. Many high performance cars in the 1970s used carefully arranged air intakes and "tuned" exhaust systems to "push" air into and out of the cylinders, making use of the resonance of the system. Two-stroke engines take this concept even further with expansion chambers that returns the escaping air-fuel mixture back to the cylinder. A more modern technique, variable valve timing, attempts to address changes in volumetric efficiency with changes in RPM of the engine: at higher RPM the engine needs the valves open for a greater percentage of the cycle time to move the charge in and out of the engine.
Volumetric efficiencies above 100% can be reached by using forced induction such as supercharging or turbocharging.
More "radical" solutions include the sleeve valve design, in which the valves are replaced outright with a rotating sleeve around the piston, or alternately a rotating sleeve under the cylinder head. In this system the ports can be as large as necessary, up to that of the entire cylinder wall. However there is a practical upper limit due to the strength of the sleeve, at larger sizes the pressure inside the cylinder can "pop" the sleeve if the port is too large.
Volumetric Efficiency is frequently abbreviated as "VE" when discussing engine efficiency.
If you have a 1 liter flask at atmospheric pressure (~14.5psi) and you double the pressure in you 1 liter flask to 29psi or 2 atmospheres you have doubled the VE.
I think AirFlow may be wanting to describe fill efficiency of the cylinder. Because of valve overlap and remaining exhaust in the cylinder, you may never get 100% fill efficiency. You might get a 90% fill of 2, 3, or 4 atmospheres of air (i.e. 29, 43.5, or 58 psi). Guys got to get your terms correct when you start discussing this stuff. Been 32 years since I did my thermo courses, so don't make go back and break out my text books.
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
