Define Boost and Vacuum For Me
08-06-04, 10:39 AM
#1
Junior Member
Thread Starter
Join Date: May 2004
Location: ct
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
Define Boost and Vacuum For Me
as im still learning...
boost is anything above atmospheric psi, right? an air compressor for your air tools creats boost, does it not? stagnat air, is atmospheric psi. hit the nozzle on the compressor hose, and psi is released.
now, the engine sucks. meaning has vaccum. in order to create boost, does the boosting device first have to create enough psi to equilize the vaccum before iot can begin injecting a psi greater than atmospheric?
i personally think this is a good question, so please dont flame or no0bitize me. im just trying to learn therories here.
crista
boost is anything above atmospheric psi, right? an air compressor for your air tools creats boost, does it not? stagnat air, is atmospheric psi. hit the nozzle on the compressor hose, and psi is released.
now, the engine sucks. meaning has vaccum. in order to create boost, does the boosting device first have to create enough psi to equilize the vaccum before iot can begin injecting a psi greater than atmospheric?
i personally think this is a good question, so please dont flame or no0bitize me. im just trying to learn therories here.
crista
08-07-04, 09:15 PM
#4
Plastic Jedi
Join Date: Sep 2002
Location: Kentwood, Michigan
Posts: 583
Likes: 0
Received 0 Likes
on
0 Posts
1st, air pressure = amount of air. Atmospheric pressure = just normal air we breathe, hear sounds in, toss paper airplanes, etc. The pressure is from gravity holding our atmosphere to the earth, it's actually the weight of all that air.
Boost = positive - more than atmospheric - air pressure, so it pushes on things. It's slang for pressurizing the motor's intake air more than atmospheric to force more air into the motor. Force more fuel in also (air-fuel ratio is critical) and out comes more power! It's a wonderful thing.
Vacuum = negative - less than atmospheric - air pressure, so it gets pushed on by air that's at atmospheric pressure. How does it apply to motors? All internal-combustion motors are air pumps. They have a cycle:
1) Intake - mechanically sucking air-fuel mixture into a chamber by increasing the chamber volume, then
2) Compression: squeezing the mixture by decreasing that chamber volume, and
3) Combustion: setting it on fire so that it's rapidly expanding gases expand the chamber volume and do work to move the car, then,
4) Exhaust: the chamber volume decreases but a port is opened for the burned gages to exit, and then the cycle repeats...
Vacuum is created in NA (or naturally aspirated, unboosted) motors by the first step, Intake. At operating speed the motor is sucking so much air out of the intake manifold that there's less pressure in there than the ordinary atmosphere out in the engine compartment. We measure that negative pressure as vacuum, and it's useful as a measure of how much air the motor's sucking in.
Hope this helps!
Boost = positive - more than atmospheric - air pressure, so it pushes on things. It's slang for pressurizing the motor's intake air more than atmospheric to force more air into the motor. Force more fuel in also (air-fuel ratio is critical) and out comes more power! It's a wonderful thing.
Vacuum = negative - less than atmospheric - air pressure, so it gets pushed on by air that's at atmospheric pressure. How does it apply to motors? All internal-combustion motors are air pumps. They have a cycle:
1) Intake - mechanically sucking air-fuel mixture into a chamber by increasing the chamber volume, then
2) Compression: squeezing the mixture by decreasing that chamber volume, and
3) Combustion: setting it on fire so that it's rapidly expanding gases expand the chamber volume and do work to move the car, then,
4) Exhaust: the chamber volume decreases but a port is opened for the burned gages to exit, and then the cycle repeats...
Vacuum is created in NA (or naturally aspirated, unboosted) motors by the first step, Intake. At operating speed the motor is sucking so much air out of the intake manifold that there's less pressure in there than the ordinary atmosphere out in the engine compartment. We measure that negative pressure as vacuum, and it's useful as a measure of how much air the motor's sucking in.
Hope this helps!
Thread
Thread Starter
Forum
Replies
Last Post
Jeff20B
1st Generation Specific (1979-1985)
73
09-16-18 07:16 PM
t-von
3rd Generation Specific (1993-2002)
9
09-10-15 01:56 PM
