Stock Turbo in the 02 WRX
04-26-2003, 03:53 PM
#2
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I BELIEVE its a TD-04 do a search here on i-club and u will find out more
04-28-2003, 12:01 AM
#5
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what does cfm stand for and what does it have to do with the turbo if u don't mind answering thank you
04-28-2003, 01:31 AM
#6
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Turbo flow
CFM stands for Cubic Feet Per minute. Its one of about 4 different ways turbochargers are rated for their max air flow. In this case it tells you how much air at normal atmospheric pressure can pass through the inlet of the turbo at its max flow.
Max flow is determined by several things. Mostly the internal design of the turbocharger itself, and to a lesser degree how much exhaust flow is available to drive the exhaust turbine side. When the air flow through the compressor housing approaches the speed of sound the energy required to compress and move it jumps very fast. The result is for practical purposes this max flow is all you can expect the turbo to move effeciently. If you over rev the turbo beyond its design speed it will flow a little more but not effeciently. When you push the turbo that hard it causes a great deal of heating of the compressed air beyond what is normal.
The TD04L has a maximum thermal effeciency in the high 70% range If I recall its about 78% at its peak effeciency. Near max flow it drops to 60% or less. This means nearly 40% of the work done to compress the air is in the form of heat. This can give you discharge temperatures near 300 Deg F under high boost.
This turbo is most effecient at flow rates that correspond to a 2 liter engine at about 4000-5000 rpm. That also happens to be the peak torque rpm of the WRX for the same reason.
If you know the max CFM available from the turbo you can get a ball park idea of the max power the turbo will support if the engine will handle it. The rule of thumb is about 1.5 CFM/hp in most engines. As you can see that gives a max effecient horse power out of this turbo of about 240 Hp. You can briefly get more -- up in the 270 hp range, but at the expense of excess heating of the air charge which makes the Inter cooler work harder and can lead to detonation due to the hot air going into the engine.
Larry
Max flow is determined by several things. Mostly the internal design of the turbocharger itself, and to a lesser degree how much exhaust flow is available to drive the exhaust turbine side. When the air flow through the compressor housing approaches the speed of sound the energy required to compress and move it jumps very fast. The result is for practical purposes this max flow is all you can expect the turbo to move effeciently. If you over rev the turbo beyond its design speed it will flow a little more but not effeciently. When you push the turbo that hard it causes a great deal of heating of the compressed air beyond what is normal.
The TD04L has a maximum thermal effeciency in the high 70% range If I recall its about 78% at its peak effeciency. Near max flow it drops to 60% or less. This means nearly 40% of the work done to compress the air is in the form of heat. This can give you discharge temperatures near 300 Deg F under high boost.
This turbo is most effecient at flow rates that correspond to a 2 liter engine at about 4000-5000 rpm. That also happens to be the peak torque rpm of the WRX for the same reason.
If you know the max CFM available from the turbo you can get a ball park idea of the max power the turbo will support if the engine will handle it. The rule of thumb is about 1.5 CFM/hp in most engines. As you can see that gives a max effecient horse power out of this turbo of about 240 Hp. You can briefly get more -- up in the 270 hp range, but at the expense of excess heating of the air charge which makes the Inter cooler work harder and can lead to detonation due to the hot air going into the engine.
Larry
04-28-2003, 09:44 AM
#7
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Re: Turbo flow
Originally posted by hotrod
CFM stands for Cubic Feet Per minute. Its one of about 4 different ways turbochargers are rated for their max air flow. In this case it tells you how much air at normal atmospheric pressure can pass through the inlet of the turbo at its max flow.
Max flow is determined by several things. Mostly the internal design of the turbocharger itself, and to a lesser degree how much exhaust flow is available to drive the exhaust turbine side. When the air flow through the compressor housing approaches the speed of sound the energy required to compress and move it jumps very fast. The result is for practical purposes this max flow is all you can expect the turbo to move effeciently. If you over rev the turbo beyond its design speed it will flow a little more but not effeciently. When you push the turbo that hard it causes a great deal of heating of the compressed air beyond what is normal.
The TD04L has a maximum thermal effeciency in the high 70% range If I recall its about 78% at its peak effeciency. Near max flow it drops to 60% or less. This means nearly 40% of the work done to compress the air is in the form of heat. This can give you discharge temperatures near 300 Deg F under high boost.
This turbo is most effecient at flow rates that correspond to a 2 liter engine at about 4000-5000 rpm. That also happens to be the peak torque rpm of the WRX for the same reason.
If you know the max CFM available from the turbo you can get a ball park idea of the max power the turbo will support if the engine will handle it. The rule of thumb is about 1.5 CFM/hp in most engines. As you can see that gives a max effecient horse power out of this turbo of about 240 Hp. You can briefly get more -- up in the 270 hp range, but at the expense of excess heating of the air charge which makes the Inter cooler work harder and can lead to detonation due to the hot air going into the engine.
Larry
CFM stands for Cubic Feet Per minute. Its one of about 4 different ways turbochargers are rated for their max air flow. In this case it tells you how much air at normal atmospheric pressure can pass through the inlet of the turbo at its max flow.
Max flow is determined by several things. Mostly the internal design of the turbocharger itself, and to a lesser degree how much exhaust flow is available to drive the exhaust turbine side. When the air flow through the compressor housing approaches the speed of sound the energy required to compress and move it jumps very fast. The result is for practical purposes this max flow is all you can expect the turbo to move effeciently. If you over rev the turbo beyond its design speed it will flow a little more but not effeciently. When you push the turbo that hard it causes a great deal of heating of the compressed air beyond what is normal.
The TD04L has a maximum thermal effeciency in the high 70% range If I recall its about 78% at its peak effeciency. Near max flow it drops to 60% or less. This means nearly 40% of the work done to compress the air is in the form of heat. This can give you discharge temperatures near 300 Deg F under high boost.
This turbo is most effecient at flow rates that correspond to a 2 liter engine at about 4000-5000 rpm. That also happens to be the peak torque rpm of the WRX for the same reason.
If you know the max CFM available from the turbo you can get a ball park idea of the max power the turbo will support if the engine will handle it. The rule of thumb is about 1.5 CFM/hp in most engines. As you can see that gives a max effecient horse power out of this turbo of about 240 Hp. You can briefly get more -- up in the 270 hp range, but at the expense of excess heating of the air charge which makes the Inter cooler work harder and can lead to detonation due to the hot air going into the engine.
Larry
04-28-2003, 11:38 AM
#8
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Location: Flying on the H1 w/ 75 psi of compression on all 4 cyl
Posts: 2,859
Car Info: PnP VF30 w/ STi injectors Perrin intake walbro fuel pump w/ a TXS TBE
wow that was awsome thanks i made a copy of that to add to my book of knowledge thanks hot rod 
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