Turbo 101
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Joined: Nov 2002
Posts: 5,322
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From: HuntsVEGAS, AL
Turbo 101
After all the reading and research, I'm still lacking the knowledge of understanding the detail workings and functions of the turbo. So many terms and jargons that I can't relate to... Boost Master, your Padawan learner awaits. Teach me the ways of the turbo 
call me Smokie Smokerson
Joined: Aug 2002
Posts: 1,665
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From: Southern California
http://auto.howstuffworks.com/turbo.htm
This site is GREAT. It has visuals & demos to really show you what goes on....
This site is GREAT. It has visuals & demos to really show you what goes on....
Thread Starter
Joined: Nov 2002
Posts: 5,322
Likes: 6
From: HuntsVEGAS, AL
Originally posted by r0t0r-rooter
http://auto.howstuffworks.com/turbo.htm
This site is GREAT. It has visuals & demos to really show you what goes on....
http://auto.howstuffworks.com/turbo.htm
This site is GREAT. It has visuals & demos to really show you what goes on....
Rotorhead
Joined: Feb 2001
Posts: 9,136
Likes: 39
From: Charlottesville, Virginia, USA
Available from most online book sellers:
http://www.amazon.com/exec/obidos/tg...l/-/0837601606
http://www.amazon.com/exec/obidos/tg...l/-/0837601606
The Power of 1.3
Joined: Aug 2001
Posts: 2,835
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From: Shrewsbury, Massachusetts
I'll add what I can.
Lets start with terms. Blow off Valve, or BOV. When you accelerate and the turbos build boost, it all gets fed into the engine. When you let off the gas, theres still some pressurized air on it's way from the turbos to the engine, and it needs somewhere to go. The throttle butterflies are closed, so it can't go there. Ther turbos are pushing it out, so it can't go there. It goes out the BOV, which basically just vents it off. The stock BOV vents it (the compressed air) back into the intake box, to suppress the noise of it. Most aftermarket BOVs vent it to the atmosphere, so you get that cool pfffsssssst sound.
Wastegate. This is a flapper door type of thing, thats controlled electronically by the ECU. The exhaust gasses that pass through the turbos first need to go through this. It is fully open until you reach the maximum boost pressure (10 psi when stock) and then it starts to close to send some of the exhaust gasses around the turbos, which slows them down and keeps them from building more boost. It is actively duty controlled, meaning that the ECU is contstantly monitering boost pressure and adjusting the wastegate as necessary to keep the pressure at 10 psi.
Boost creep. This goes hand in hand with the wastegate. When the engine is modded, there is a point where too much air is going through it for the stock wastegate to handle. Its opening is only so big, and if the volume of air/sec coming out of the engine is greater than its opening will allow, some of the gasses will start going back into the turbos, and they'll spin faster and faster, creating a slow building of boost over the desired level; a creep, if you will. This is remedied by boring out the wastegate, which makes the hole larger.
Lets start with terms. Blow off Valve, or BOV. When you accelerate and the turbos build boost, it all gets fed into the engine. When you let off the gas, theres still some pressurized air on it's way from the turbos to the engine, and it needs somewhere to go. The throttle butterflies are closed, so it can't go there. Ther turbos are pushing it out, so it can't go there. It goes out the BOV, which basically just vents it off. The stock BOV vents it (the compressed air) back into the intake box, to suppress the noise of it. Most aftermarket BOVs vent it to the atmosphere, so you get that cool pfffsssssst sound.
Wastegate. This is a flapper door type of thing, thats controlled electronically by the ECU. The exhaust gasses that pass through the turbos first need to go through this. It is fully open until you reach the maximum boost pressure (10 psi when stock) and then it starts to close to send some of the exhaust gasses around the turbos, which slows them down and keeps them from building more boost. It is actively duty controlled, meaning that the ECU is contstantly monitering boost pressure and adjusting the wastegate as necessary to keep the pressure at 10 psi.
Boost creep. This goes hand in hand with the wastegate. When the engine is modded, there is a point where too much air is going through it for the stock wastegate to handle. Its opening is only so big, and if the volume of air/sec coming out of the engine is greater than its opening will allow, some of the gasses will start going back into the turbos, and they'll spin faster and faster, creating a slow building of boost over the desired level; a creep, if you will. This is remedied by boring out the wastegate, which makes the hole larger.
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Thread Starter
Joined: Nov 2002
Posts: 5,322
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From: HuntsVEGAS, AL
Originally posted by 911GT2
I'll add what I can.
Lets start with terms. Blow off Valve, or BOV. When you accelerate and the turbos build boost, it all gets fed into the engine. When you let off the gas, theres still some pressurized air on it's way from the turbos to the engine, and it needs somewhere to go. The throttle butterflies are closed, so it can't go there. Ther turbos are pushing it out, so it can't go there. It goes out the BOV, which basically just vents it off. The stock BOV vents it (the compressed air) back into the intake box, to suppress the noise of it. Most aftermarket BOVs vent it to the atmosphere, so you get that cool pfffsssssst sound.
Wastegate. This is a flapper door type of thing, thats controlled electronically by the ECU. The exhaust gasses that pass through the turbos first need to go through this. It is fully open until you reach the maximum boost pressure (10 psi when stock) and then it starts to close to send some of the exhaust gasses around the turbos, which slows them down and keeps them from building more boost. It is actively duty controlled, meaning that the ECU is contstantly monitering boost pressure and adjusting the wastegate as necessary to keep the pressure at 10 psi.
Boost creep. This goes hand in hand with the wastegate. When the engine is modded, there is a point where too much air is going through it for the stock wastegate to handle. Its opening is only so big, and if the volume of air/sec coming out of the engine is greater than its opening will allow, some of the gasses will start going back into the turbos, and they'll spin faster and faster, creating a slow building of boost over the desired level; a creep, if you will. This is remedied by boring out the wastegate, which makes the hole larger.
I'll add what I can.
Lets start with terms. Blow off Valve, or BOV. When you accelerate and the turbos build boost, it all gets fed into the engine. When you let off the gas, theres still some pressurized air on it's way from the turbos to the engine, and it needs somewhere to go. The throttle butterflies are closed, so it can't go there. Ther turbos are pushing it out, so it can't go there. It goes out the BOV, which basically just vents it off. The stock BOV vents it (the compressed air) back into the intake box, to suppress the noise of it. Most aftermarket BOVs vent it to the atmosphere, so you get that cool pfffsssssst sound.
Wastegate. This is a flapper door type of thing, thats controlled electronically by the ECU. The exhaust gasses that pass through the turbos first need to go through this. It is fully open until you reach the maximum boost pressure (10 psi when stock) and then it starts to close to send some of the exhaust gasses around the turbos, which slows them down and keeps them from building more boost. It is actively duty controlled, meaning that the ECU is contstantly monitering boost pressure and adjusting the wastegate as necessary to keep the pressure at 10 psi.
Boost creep. This goes hand in hand with the wastegate. When the engine is modded, there is a point where too much air is going through it for the stock wastegate to handle. Its opening is only so big, and if the volume of air/sec coming out of the engine is greater than its opening will allow, some of the gasses will start going back into the turbos, and they'll spin faster and faster, creating a slow building of boost over the desired level; a creep, if you will. This is remedied by boring out the wastegate, which makes the hole larger.
Rotorhead
Joined: Feb 2001
Posts: 9,136
Likes: 39
From: Charlottesville, Virginia, USA
Originally posted by 911GT2
Wastegate. This is a flapper door type of thing, thats controlled electronically by the ECU. The exhaust gasses that pass through the turbos first need to go through this. It is fully open until you reach the maximum boost pressure (10 psi when stock) and then it starts to close to send some of the exhaust gasses around the turbos, which slows them down and keeps them from building more boost.
Wastegate. This is a flapper door type of thing, thats controlled electronically by the ECU. The exhaust gasses that pass through the turbos first need to go through this. It is fully open until you reach the maximum boost pressure (10 psi when stock) and then it starts to close to send some of the exhaust gasses around the turbos, which slows them down and keeps them from building more boost.
Originally posted by HDP
Well, what would cause sporadic boost patterns?
Well, what would cause sporadic boost patterns?
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