SeattleSy#1255
Category 5 Conservative
Was wondering exactly what vacuum is? I understand the concept of boost (forced air) but what exactly is going on when "in vacuum"?
I'm learning here
I'm learning here
What is Vacuum?
- Thread starter SeattleSy#1255
- Start date
TheObiJuan
Active member
what is the absence of air? aha, you have the answer 8)
SeattleSy#1255
Category 5 Conservative
so your saying that vacuum is the absence of air? Really, hmm ok?
The internal combustion engine is basically an air pump. As the pistons go down, the rings seal the cylinder walls and suck in air. This is called negative pressure or vacuum. In our case air is forced into the cylinders as soon as the valves open because of the turbo. This is called forced induction. On your boost gauge you can see when the engine is sucking air in or you can see air being forced in.
TheObiJuan
Active member
SeattleSy#1255, space is a vaccum too.
when the cylinders have no air in them, then they are in vaccum.
when they have boost, then they have air in them, in massive quantities too.
when the cylinders have no air in them, then they are in vaccum.
when they have boost, then they have air in them, in massive quantities too.
You need to think of it in terms of relative pressures.
The Manifold absolute pressure sensor (MAP) measures off of an absolute scale.
Vacuum is generated as the pressure in the cylinder is less than the atmospheric pressure, so air moves from the higher pressure to the lower pressure area. The pressure in the cylinder is less than the atmospheric pressure as the volume increases (the piston drops in the cylinder) while it is sealed off (valves closed) then the intake valve opens. The higher outside pressure pushes air into the cylinder. The easier it is for air to move into the cylinder, the more air can be burned by combustion, and the more horsepower you can make. How do you make it easier to get more air into a cylinder? Port the heads, port the intake etc. Less restriction means more airflow into the cylinder. When you use forced induction, you are actually increasing the pressure pushing air into the cylinder. It is shown/read as boost, as everyone's reference for pressure is atmospheric pressure. The mix of oxygen, nitrogen, water vapor etc exhibits about 15psi pressure on you and your surroundings (at sea level). Absolute zero pressure is the lack of any material/pressure.
It can get confusing, but if you pick up a basic science/physics book you can understand the concept easily enough to adapt to the automotive side.
Hope that helps out, if not, post your questions...
The Manifold absolute pressure sensor (MAP) measures off of an absolute scale.
Vacuum is generated as the pressure in the cylinder is less than the atmospheric pressure, so air moves from the higher pressure to the lower pressure area. The pressure in the cylinder is less than the atmospheric pressure as the volume increases (the piston drops in the cylinder) while it is sealed off (valves closed) then the intake valve opens. The higher outside pressure pushes air into the cylinder. The easier it is for air to move into the cylinder, the more air can be burned by combustion, and the more horsepower you can make. How do you make it easier to get more air into a cylinder? Port the heads, port the intake etc. Less restriction means more airflow into the cylinder. When you use forced induction, you are actually increasing the pressure pushing air into the cylinder. It is shown/read as boost, as everyone's reference for pressure is atmospheric pressure. The mix of oxygen, nitrogen, water vapor etc exhibits about 15psi pressure on you and your surroundings (at sea level). Absolute zero pressure is the lack of any material/pressure.
It can get confusing, but if you pick up a basic science/physics book you can understand the concept easily enough to adapt to the automotive side.
Hope that helps out, if not, post your questions...
TheObiJuan
Active member
yep, that about does it. thanks bg.
like i said, you are the shit.lol 8)
like i said, you are the shit.lol 8)
Will_in_China
Truckless Wonder
Re: What is Vacuum?
Turbo Blow
Vacuum Suck
SeattleSy#1255 said:Was wondering exactly what vacuum is? I understand the concept of boost (forced air) but what exactly is going on when "in vacuum"?
I'm learning here
Turbo Blow
Vacuum Suck
Will_in_China
Truckless Wonder
NWSTP Eastside said:
Those were instructions for the next time you are bored, Jeff!
TheObiJuan
Active member
any specific model of vaccum cleaner recommended. what was that one scary movie or whatever it was called with doofy. he like it.
SeattleSy#1255
Category 5 Conservative
Great info guys...thanks alot, i'm trying to understand how things work, so that is big time help...What is it exactly that forced air, or air for that matter does to make power?
also, is it safe to say that a supercharger's purpose is to force air as well only just using a different mechanism to do so?
also, is it safe to say that a supercharger's purpose is to force air as well only just using a different mechanism to do so?
TheObiJuan
Active member
yep. supercharger and turbochargers same purpose. they just have differenet ways of getting there. turbo creates a lot of heat, superchargers are parasitic.
go to howstuffworks.com cool place. you can learn a lot there.
its all about a good combustion. (explosion) that is what pushes the piston down and turns the crank. the better the combustion, the faster it goes down. more power.
if you have more air and fuel, you get a bigger, badder, meaner combustion.
so forced air with lots of gas=shit loads of power.
go to howstuffworks.com cool place. you can learn a lot there.
its all about a good combustion. (explosion) that is what pushes the piston down and turns the crank. the better the combustion, the faster it goes down. more power.
if you have more air and fuel, you get a bigger, badder, meaner combustion.
so forced air with lots of gas=shit loads of power.
Just to sound engineer-like, let's not call more powerful combustion "better" combustion.
Otherwise, a top fuel nitromethane motor would have the BEST combustion ever... it is pretty cool, but the best combustion depends on what you want.. durability/reliability, power, etc.
Otherwise, a top fuel nitromethane motor would have the BEST combustion ever... it is pretty cool, but the best combustion depends on what you want.. durability/reliability, power, etc.
warmpancakes
New member
hey whats wrong with engineers?
Lynn D. Brown
New member
What is Vacuum ?
What is Vacuum ?
I tried to give a long semi scientific explanation, but it wouldn't go thru. Just got a different Operating System on my other computer. Not sure that alot of this damned Zone Alarm/Virus shit isn't interferring.
What is Vacuum ?
I tried to give a long semi scientific explanation, but it wouldn't go thru. Just got a different Operating System on my other computer. Not sure that alot of this damned Zone Alarm/Virus shit isn't interferring.