Truth about S/C vs T/C..
01-08-2005, 04:30 AM
#1
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Truth about S/C vs T/C..
Talk to two people, and you will get three answers. Here are some consideration's in deciding which one is the right choice for you:
Turbochargers fit easy on straight 4 or 6 cylinder engines. They must be fitted as close as possible to the head.
TC's must run very hot, just short of melting down. This requires that the surrounding of the TC must be well insulated from radiation heat, and that the engine must be kept idling for a minute or two after heavy use before switching off. Obviously, the turbo is water-cooled.
TC's must run hot because they rely on the exhaust gas velocity, which is directly proportional to the temperature.
TC's have turbo lag, the time it takes to wind the "fan" up. This is less noticeable with automatics or during manual gear shift, but very noticeable during a "standing start".
TC's are more commonly used in diesel engines.
TC's are used more frequently in Europe because smaller engines (4 cylinders) are more common.
TC's require a special exhaust branch, which must be made of high temperature material, if possible with no heat expansion ! Otherwise your exhaust branch gasket will not last.
You can fit two TC's on a V6 or V8, it works. But you must choose the TC carefully, and you have twice the radiation heat problem, twice the cost.
SC's are used exclusively in acceleration racing, because the turbo lag can't be tolerated.
Depending on the type of SC you are considering, the fitting varies from being outright impossible to easy as fitting an air-conditioner pump.
TC's are used on constant load engines such as trucks, marine engines and power-plants.
There are many types of SC's, but only one type TC. The selection of the correct size and manufacturer of either TC or SC is an art, which should be left to the experts. Many technical books have been written about it and free advice is available from the manufacturers of TC's or SC's.
When you look at the boost pressure curve of TC's and SC's, the SC's don't look too impressive. This is because they have to be geared to produce the maximum boost pressure at high RPM. In comparison, a TC has a regulation device built in, which opens a "waste gate" once the maximum boost has been reached. The TC curve doesn't explain the turbo lag !
A TC produces more power at low RPM, because a well selected TC produces the maximum boost between 1500 to 2500 RPM, when the waste gate starts to open. This operating mode may be useful for 4x4's. In the latest TC design, the turbo's fan's became smaller, the waste gate bigger, and the turbo speed higher.
TC's can't really produce very high boost pressure, above 1.5 bar (21 psi). Someone will prove me wrong, I am sure. But TC's are used normally between 0.4 to 1.2 bar (6 psi to 17 psi).
Another way to explain the turbo lag: A TC works on the chain reaction principle, it is the starting of the chain which produces the lag. Lets assume the engine idles and so does the turbo. The boost pressure is ZERO. Then you open the throttle to a particular point and keep it there. The engine operates in a decompressed state and produces very little power. The little power it makes raises the exhaust gas temperature and velocity. This makes the turbo spin a little faster and raises the boost pressure, which in turn makes a little more power, which in turn.....(the chain reaction sets in). The chain reaction is limited by the waste gate regulation, and the airflow through your butterflies. Also, the TC can limit the boost pressure, or RPM limits can come in, or your engine blows up.
SC's are more predictable in engineering terms. From the manufacturers data you can choose the correct gearing for the desired boost pressure and RPM.
SC's are more expensive and difficult to manufacture.
SC's are heating the boost air to the same extent as TC's, but the fitting of intercoolers is hardly every done to the roots type.
Summary: If you have a straight engine, not used in a dragster, consider a TC: it's less expensive, but requires a little engineering. Otherwise look at a SC. Make a market research as to the types, size, lubrication, cooling and gearing required.
If you are building dragsters, it must be a SC, and your choices are limited to two or three manufacturers, which are helpful in providing kits and free advice.
Sorry its so long, lol!
_____
Turbochargers fit easy on straight 4 or 6 cylinder engines. They must be fitted as close as possible to the head.
TC's must run very hot, just short of melting down. This requires that the surrounding of the TC must be well insulated from radiation heat, and that the engine must be kept idling for a minute or two after heavy use before switching off. Obviously, the turbo is water-cooled.
TC's must run hot because they rely on the exhaust gas velocity, which is directly proportional to the temperature.
TC's have turbo lag, the time it takes to wind the "fan" up. This is less noticeable with automatics or during manual gear shift, but very noticeable during a "standing start".
TC's are more commonly used in diesel engines.
TC's are used more frequently in Europe because smaller engines (4 cylinders) are more common.
TC's require a special exhaust branch, which must be made of high temperature material, if possible with no heat expansion ! Otherwise your exhaust branch gasket will not last.
You can fit two TC's on a V6 or V8, it works. But you must choose the TC carefully, and you have twice the radiation heat problem, twice the cost.
SC's are used exclusively in acceleration racing, because the turbo lag can't be tolerated.
Depending on the type of SC you are considering, the fitting varies from being outright impossible to easy as fitting an air-conditioner pump.
TC's are used on constant load engines such as trucks, marine engines and power-plants.
There are many types of SC's, but only one type TC. The selection of the correct size and manufacturer of either TC or SC is an art, which should be left to the experts. Many technical books have been written about it and free advice is available from the manufacturers of TC's or SC's.
When you look at the boost pressure curve of TC's and SC's, the SC's don't look too impressive. This is because they have to be geared to produce the maximum boost pressure at high RPM. In comparison, a TC has a regulation device built in, which opens a "waste gate" once the maximum boost has been reached. The TC curve doesn't explain the turbo lag !
A TC produces more power at low RPM, because a well selected TC produces the maximum boost between 1500 to 2500 RPM, when the waste gate starts to open. This operating mode may be useful for 4x4's. In the latest TC design, the turbo's fan's became smaller, the waste gate bigger, and the turbo speed higher.
TC's can't really produce very high boost pressure, above 1.5 bar (21 psi). Someone will prove me wrong, I am sure. But TC's are used normally between 0.4 to 1.2 bar (6 psi to 17 psi).
Another way to explain the turbo lag: A TC works on the chain reaction principle, it is the starting of the chain which produces the lag. Lets assume the engine idles and so does the turbo. The boost pressure is ZERO. Then you open the throttle to a particular point and keep it there. The engine operates in a decompressed state and produces very little power. The little power it makes raises the exhaust gas temperature and velocity. This makes the turbo spin a little faster and raises the boost pressure, which in turn makes a little more power, which in turn.....(the chain reaction sets in). The chain reaction is limited by the waste gate regulation, and the airflow through your butterflies. Also, the TC can limit the boost pressure, or RPM limits can come in, or your engine blows up.
SC's are more predictable in engineering terms. From the manufacturers data you can choose the correct gearing for the desired boost pressure and RPM.
SC's are more expensive and difficult to manufacture.
SC's are heating the boost air to the same extent as TC's, but the fitting of intercoolers is hardly every done to the roots type.
Summary: If you have a straight engine, not used in a dragster, consider a TC: it's less expensive, but requires a little engineering. Otherwise look at a SC. Make a market research as to the types, size, lubrication, cooling and gearing required.
If you are building dragsters, it must be a SC, and your choices are limited to two or three manufacturers, which are helpful in providing kits and free advice.
Sorry its so long, lol!
_____
Last edited by MR_LUV; 09-05-2019 at 09:14 AM. Reason: Awarded 10 Year Badge
01-08-2005, 08:20 AM
#2
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Posts: 119
Re: truth about sc vs tc
ICLUB this post is useless most of the info is just wrong or too general to be useful to the extent that I do not even want to waste time correcting all of it it.
Just three little wonders:
1) TC do not have to run hot. They get hot but that's a byproduct.
2) How is exhaust gas temperature proportional to its speed evacuating cylinder block?
3) The TC boost is ZERO only when the engine is off hence the lack of turbo lag in newer TC designs. It may get to negative, though, but that's another story (deceleration)
Just three little wonders:
1) TC do not have to run hot. They get hot but that's a byproduct.
2) How is exhaust gas temperature proportional to its speed evacuating cylinder block?
3) The TC boost is ZERO only when the engine is off hence the lack of turbo lag in newer TC designs. It may get to negative, though, but that's another story (deceleration)
Originally Posted by ICLUB2
Talk to two people, and you will get three answers. Here are some consideration's in deciding which one is the right choice for you:
Turbochargers fit easy on straight 4 or 6 cylinder engines. They must be fitted as close as possible to the head.
TC's must run very hot, just short of melting down. This requires that the surrounding of the TC must be well insulated from radiation heat, and that the engine must be kept idling for a minute or two after heavy use before switching off. Obviously, the turbo is water-cooled.
TC's must run hot because they rely on the exhaust gas velocity, which is directly proportional to the temperature.
TC's have turbo lag, the time it takes to wind the "fan" up. This is less noticeable with automatics or during manual gear shift, but very noticeable during a "standing start".
TC's are more commonly used in diesel engines.
TC's are used more frequently in Europe because smaller engines (4 cylinders) are more common.
TC's require a special exhaust branch, which must be made of high temperature material, if possible with no heat expansion ! Otherwise your exhaust branch gasket will not last.
You can fit two TC's on a V6 or V8, it works. But you must choose the TC carefully, and you have twice the radiation heat problem, twice the cost.
SC's are used exclusively in acceleration racing, because the turbo lag can't be tolerated.
Depending on the type of SC you are considering, the fitting varies from being outright impossible to easy as fitting an air-conditioner pump.
TC's are used on constant load engines such as trucks, marine engines and power-plants.
There are many types of SC's, but only one type TC. The selection of the correct size and manufacturer of either TC or SC is an art, which should be left to the experts. Many technical books have been written about it and free advice is available from the manufacturers of TC's or SC's.
When you look at the boost pressure curve of TC's and SC's, the SC's don't look too impressive. This is because they have to be geared to produce the maximum boost pressure at high RPM. In comparison, a TC has a regulation device built in, which opens a "waste gate" once the maximum boost has been reached. The TC curve doesn't explain the turbo lag !
A TC produces more power at low RPM, because a well selected TC produces the maximum boost between 1500 to 2500 RPM, when the waste gate starts to open. This operating mode may be useful for 4x4's. In the latest TC design, the turbo's fan's became smaller, the waste gate bigger, and the turbo speed higher.
TC's can't really produce very high boost pressure, above 1.5 bar (21 psi). Someone will prove me wrong, I am sure. But TC's are used normally between 0.4 to 1.2 bar (6 psi to 17 psi).
Another way to explain the turbo lag: A TC works on the chain reaction principle, it is the starting of the chain which produces the lag. Lets assume the engine idles and so does the turbo. The boost pressure is ZERO. Then you open the throttle to a particular point and keep it there. The engine operates in a decompressed state and produces very little power. The little power it makes raises the exhaust gas temperature and velocity. This makes the turbo spin a little faster and raises the boost pressure, which in turn makes a little more power, which in turn.....(the chain reaction sets in). The chain reaction is limited by the waste gate regulation, and the airflow through your butterflies. Also, the TC can limit the boost pressure, or RPM limits can come in, or your engine blows up.
SC's are more predictable in engineering terms. From the manufacturers data you can choose the correct gearing for the desired boost pressure and RPM.
SC's are more expensive and difficult to manufacture.
SC's are heating the boost air to the same extent as TC's, but the fitting of intercoolers is hardly every done to the roots type.
Summary: If you have a straight engine, not used in a dragster, consider a TC: it's less expensive, but requires a little engineering. Otherwise look at a SC. Make a market research as to the types, size, lubrication, cooling and gearing required. If you are building dragsters, it must be a SC, and your choices are limited to two or three manufacturers, which are helpful in providing kits and free advice.
sorry its so long, lol!
Turbochargers fit easy on straight 4 or 6 cylinder engines. They must be fitted as close as possible to the head.
TC's must run very hot, just short of melting down. This requires that the surrounding of the TC must be well insulated from radiation heat, and that the engine must be kept idling for a minute or two after heavy use before switching off. Obviously, the turbo is water-cooled.
TC's must run hot because they rely on the exhaust gas velocity, which is directly proportional to the temperature.
TC's have turbo lag, the time it takes to wind the "fan" up. This is less noticeable with automatics or during manual gear shift, but very noticeable during a "standing start".
TC's are more commonly used in diesel engines.
TC's are used more frequently in Europe because smaller engines (4 cylinders) are more common.
TC's require a special exhaust branch, which must be made of high temperature material, if possible with no heat expansion ! Otherwise your exhaust branch gasket will not last.
You can fit two TC's on a V6 or V8, it works. But you must choose the TC carefully, and you have twice the radiation heat problem, twice the cost.
SC's are used exclusively in acceleration racing, because the turbo lag can't be tolerated.
Depending on the type of SC you are considering, the fitting varies from being outright impossible to easy as fitting an air-conditioner pump.
TC's are used on constant load engines such as trucks, marine engines and power-plants.
There are many types of SC's, but only one type TC. The selection of the correct size and manufacturer of either TC or SC is an art, which should be left to the experts. Many technical books have been written about it and free advice is available from the manufacturers of TC's or SC's.
When you look at the boost pressure curve of TC's and SC's, the SC's don't look too impressive. This is because they have to be geared to produce the maximum boost pressure at high RPM. In comparison, a TC has a regulation device built in, which opens a "waste gate" once the maximum boost has been reached. The TC curve doesn't explain the turbo lag !
A TC produces more power at low RPM, because a well selected TC produces the maximum boost between 1500 to 2500 RPM, when the waste gate starts to open. This operating mode may be useful for 4x4's. In the latest TC design, the turbo's fan's became smaller, the waste gate bigger, and the turbo speed higher.
TC's can't really produce very high boost pressure, above 1.5 bar (21 psi). Someone will prove me wrong, I am sure. But TC's are used normally between 0.4 to 1.2 bar (6 psi to 17 psi).
Another way to explain the turbo lag: A TC works on the chain reaction principle, it is the starting of the chain which produces the lag. Lets assume the engine idles and so does the turbo. The boost pressure is ZERO. Then you open the throttle to a particular point and keep it there. The engine operates in a decompressed state and produces very little power. The little power it makes raises the exhaust gas temperature and velocity. This makes the turbo spin a little faster and raises the boost pressure, which in turn makes a little more power, which in turn.....(the chain reaction sets in). The chain reaction is limited by the waste gate regulation, and the airflow through your butterflies. Also, the TC can limit the boost pressure, or RPM limits can come in, or your engine blows up.
SC's are more predictable in engineering terms. From the manufacturers data you can choose the correct gearing for the desired boost pressure and RPM.
SC's are more expensive and difficult to manufacture.
SC's are heating the boost air to the same extent as TC's, but the fitting of intercoolers is hardly every done to the roots type.
Summary: If you have a straight engine, not used in a dragster, consider a TC: it's less expensive, but requires a little engineering. Otherwise look at a SC. Make a market research as to the types, size, lubrication, cooling and gearing required. If you are building dragsters, it must be a SC, and your choices are limited to two or three manufacturers, which are helpful in providing kits and free advice.
sorry its so long, lol!
Last edited by MR_LUV; 09-05-2019 at 09:23 AM. Reason: Awarded 10 Year Badge
01-08-2005, 09:25 AM
#3
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Posts: 114
Re: Truth about S/C vs T/C
Originally Posted by Stefan TC
ICLUB this post is useless most of the info is just wrong ot too general to be useful to the extent that I do not even want to waste time correcting all of it it. Just three little wonders: 1) TC do not have to run hot. They get hot but that's a byproduct. 2) How is exhaust gas temperature proportional to its speed evacuating cylinder block? 3) The TC boost is ZERO only when the engine is off hence the lack of turbo lag in newer TC designs. It may get to negative, though, but that's another story (deceleration)
_____
Last edited by MR_LUV; 09-05-2019 at 09:25 AM. Reason: Awarded 10 Year Badge
01-08-2005, 04:58 PM
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http://auto.howstuffworks.com/question122.htm
problem solved
the rest of if is what your personal preference and most of that is usually whether you really like the sound of spooling up and the BOV the way most people talk.
problem solved
the rest of if is what your personal preference and most of that is usually whether you really like the sound of spooling up and the BOV the way most people talk.
01-09-2005, 11:26 PM
#6
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Originally Posted by ICLUB2
TC's must run very hot, just short of melting down. This requires that the surrounding of the TC must be well insulated from radiation heat, and that the engine must be kept idling for a minute or two after heavy use before switching off. Obviously, the turbo is water-cooled.
01-10-2005, 05:08 AM
#7
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Re: truth about sc vs tc
Originally Posted by kaypee
He has good intentions, he's trying to educate people. If he's wrong, please enlighten the rest of us. Lets not get into an unnecessary flame war, shall we?
Disinformation is MUCH worse that lack if information.
Just read his summary:
Originally Posted by iclub
Summary: If you have a straight engine, not used in a dragster, consider a TC: it's less expensive, but requires a little engineering. Otherwise look at a SC. Make a market research as to the types, size, lubrication, cooling and gearing required. If you are building dragsters, it must be a SC, and your choices are limited to two or three manufacturers, which are helpful in providing kits and free advice.
It is not a flame war I just could not believe my eyes when reading "truth about sc vs tc"....
01-12-2005, 11:54 PM
#10
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Join Date: Jan 2005
Location: Miami, FL
Posts: 5
An easy way to see it
Car: Scion tC or any 4 Cyl car
Application: Street and occasional strip use
Complexity: Stage I turbo kit VS say supercharger from factory
Supercharger:
Most important/noticeable:
Pros: Flatten and quick torque curve
Cons: Lack of upgradeability
Turbo charger:
Most important/noticeable:
Pros: Higher torque peak and possibly higher HP gain
Cons: Installation and care-maintenance
While the Supercharger will have no lag, it will have just a few tricks you can do with the pulleys to gain more power and then it all about good old engine magic to continue the quest for HP/TQ numbers, the Turbo charger on the other hand, will show lag but will pull higher torque numbers resulting in a similar acceleration compared to the car equipped with the supercharger.
Now, installation but mostly the care-maintenance that you must have to ensure long life and good performance from the turbo might be the downside. Let’s not forget over-boosting that breaks turbos or engines…But that also is the added value of the turbo charging where you will be able to raise the boost to easy obtain more power.
Driving conditions: supercharged car, just like driving a car with a larger engine with noticeable higher performance, while driving a turbo car normally adds the acceleration sensation when engine speed and WOT get the turbo to boost normally around 4000RPM and away you go!
We know there are more Pros/Cons for both systems, but if you are not a race car engineer and just want to evaluate what to buy, we hope this helps.
Application: Street and occasional strip use
Complexity: Stage I turbo kit VS say supercharger from factory
Supercharger:
Most important/noticeable:
Pros: Flatten and quick torque curve
Cons: Lack of upgradeability
Turbo charger:
Most important/noticeable:
Pros: Higher torque peak and possibly higher HP gain
Cons: Installation and care-maintenance
While the Supercharger will have no lag, it will have just a few tricks you can do with the pulleys to gain more power and then it all about good old engine magic to continue the quest for HP/TQ numbers, the Turbo charger on the other hand, will show lag but will pull higher torque numbers resulting in a similar acceleration compared to the car equipped with the supercharger.
Now, installation but mostly the care-maintenance that you must have to ensure long life and good performance from the turbo might be the downside. Let’s not forget over-boosting that breaks turbos or engines…But that also is the added value of the turbo charging where you will be able to raise the boost to easy obtain more power.
Driving conditions: supercharged car, just like driving a car with a larger engine with noticeable higher performance, while driving a turbo car normally adds the acceleration sensation when engine speed and WOT get the turbo to boost normally around 4000RPM and away you go!
We know there are more Pros/Cons for both systems, but if you are not a race car engineer and just want to evaluate what to buy, we hope this helps.
01-13-2005, 02:15 AM
#11
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Posts: 2,912
my head hurts, ahh where to begin...
For starters, as said I believe, turbo's don't have to be "hot". Host exhaust gas does spin the exhaust turbine causing it to spool, this is connected to a compressor wheel which sucks in air through an intake. The compressed air increases in temperature only because of the compression of air. As air compresses it get's hotter because gas molecules are moving faster.
Yes turbo's are common on Desisel, but not uncommon on gasoline cars. Every saab is turbo charged.
Turbo lag is not tolerated? Just get a smaller turbo with appropiate trim. Most high hp drag cars are turbo charged. I usually see superchargers on domestics because typically they don't rev as high, and the torque band is lower. But every sub 12sec civic i've seen has been boosted. There's those few NA civics that are an exception.
I guess being close to the head is good, but airflow and temp is more important. Equal runner manifolds make a large difference in performance. The runners may be longer, but with the increased efficiency, they make more power, with slightly better response.
I don't know these are jsut some thigns I cought. Sciontcperformance.com, nice post.
For starters, as said I believe, turbo's don't have to be "hot". Host exhaust gas does spin the exhaust turbine causing it to spool, this is connected to a compressor wheel which sucks in air through an intake. The compressed air increases in temperature only because of the compression of air. As air compresses it get's hotter because gas molecules are moving faster.
Yes turbo's are common on Desisel, but not uncommon on gasoline cars. Every saab is turbo charged.
Turbo lag is not tolerated? Just get a smaller turbo with appropiate trim. Most high hp drag cars are turbo charged. I usually see superchargers on domestics because typically they don't rev as high, and the torque band is lower. But every sub 12sec civic i've seen has been boosted. There's those few NA civics that are an exception.
I guess being close to the head is good, but airflow and temp is more important. Equal runner manifolds make a large difference in performance. The runners may be longer, but with the increased efficiency, they make more power, with slightly better response.
I don't know these are jsut some thigns I cought. Sciontcperformance.com, nice post.
01-13-2005, 02:34 AM
#12
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Turbochargers fit easy on straight 4 or 6 cylinder engines. They must be fitted as close as possible to the head.
http://www.ststurbo.com/home
Saw it on Two Guys Garage
01-13-2005, 02:50 AM
#13
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Join Date: Dec 2004
Posts: 119
Re: An easy way to see it
Originally Posted by sciontcperformance.com
Car: Scion tC or any 4 Cyl car
Application: Street and occasional strip use
Complexity: Stage I turbo kit VS say supercharger from factory
Supercharger:
Most important/noticeable:
Pros: Flatten and quick torque curve
Cons: Lack of upgradeability
Turbo charger:
Most important/noticeable:
Pros: Higher torque peak and possibly higher HP gain
Cons: Installation and care-maintenance
While the Supercharger will have no lag, it will have just a few tricks you can do with the pulleys to gain more power and then it all about good old engine magic to continue the quest for HP/TQ numbers, the Turbo charger on the other hand, will show lag but will pull higher torque numbers resulting in a similar acceleration compared to the car equipped with the supercharger.
Now, installation but mostly the care-maintenance that you must have to ensure long life and good performance from the turbo might be the downside. Let’s not forget over-boosting that breaks turbos or engines…But that also is the added value of the turbo charging where you will be able to raise the boost to easy obtain more power.
Driving conditions: supercharged car, just like driving a car with a larger engine with noticeable higher performance, while driving a turbo car normally adds the acceleration sensation when engine speed and WOT get the turbo to boost normally around 4000RPM and away you go!
We know there are more Pros/Cons for both systems, but if you are not a race car engineer and just want to evaluate what to buy, we hope this helps.
Application: Street and occasional strip use
Complexity: Stage I turbo kit VS say supercharger from factory
Supercharger:
Most important/noticeable:
Pros: Flatten and quick torque curve
Cons: Lack of upgradeability
Turbo charger:
Most important/noticeable:
Pros: Higher torque peak and possibly higher HP gain
Cons: Installation and care-maintenance
While the Supercharger will have no lag, it will have just a few tricks you can do with the pulleys to gain more power and then it all about good old engine magic to continue the quest for HP/TQ numbers, the Turbo charger on the other hand, will show lag but will pull higher torque numbers resulting in a similar acceleration compared to the car equipped with the supercharger.
Now, installation but mostly the care-maintenance that you must have to ensure long life and good performance from the turbo might be the downside. Let’s not forget over-boosting that breaks turbos or engines…But that also is the added value of the turbo charging where you will be able to raise the boost to easy obtain more power.
Driving conditions: supercharged car, just like driving a car with a larger engine with noticeable higher performance, while driving a turbo car normally adds the acceleration sensation when engine speed and WOT get the turbo to boost normally around 4000RPM and away you go!
We know there are more Pros/Cons for both systems, but if you are not a race car engineer and just want to evaluate what to buy, we hope this helps.
Everybody is generalizing here. There is no simple answer turbo vs supercharger as the design differs... Supercharges are used commonly in spor/muscle cars such as Mercedes/AMGs and turbos in Audis and Saabs...
All depends on actuall application. As a matter of pure physics rubocharger is more efficient as it utilizes energy that would be OTHERWISE lost, i.e. exhaust gasese velocity...
As far as lag it also depends on the application and tuning. There is a trade of betwwen large turbo vs. small as the small will spool up faster but deliver less power gain. Both superchargers and turbochargers need to spool up, today's turbochargesr suffer much less from the turbo lag than 20 years ago. If you do not believe me drive a tubro car such as 2000 Saab 93 Viggen and let me know if you notice ANY turbo lag at all.... You won't.
There is no MAINTENANCE on turbos. Today's turbo;s are most oftne watercooled and do not even require cool down like they used to years ago. I do not believe in bolt-on turbo application, there is too much of art and science involved to egt that app succcesfull...
I would wait for Toyota's own supercharger as it is designed and tested for this particular engine........
Turbo car feels exactly like a car with a much larger engine, just spend some time in a factory equipped turbo car like a SAAB or Audi or Mitsu and you will know.......
My 9000 was a 2.3L turbo and you would not believe it is not a V6 or V8 whiule driving it. Incredibely responsive with NO noticeable trubo lag...
Do not believe everything you read, especiaolly when it comes from so called tuners trying to push their products.......
01-14-2005, 10:36 PM
#14
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Let's evaluate the turbocharger versus the supercharger according to several important factors.
Cost
The cost of supercharger and a turbocharger systems for the same engine are approximately the same, so cost is generally not a factor.
Lag
This is perhaps the biggest advantage that the supercharger enjoys over the tubo. Because a turbocharger is driven by exhaust gasses, the turbocharger's turbine must first spool up before it even begins to turn the compressor's impeller. This results in lag time which is the time needed for the turbine to reach its full throttle from an intermediate rotational speed state. During this lag time, the turbocharger is creating little to no boost, which means little to no power gains during this time. Smaller turbos spool up quicker, which eliminates some of this lag. Turbochargers thus utilize a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses boost pressure, and if it gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down..
A Supercharger, on the other hand, is connected directly to the crank, so there is no "lag". Superchargers are able to produce boost at a very low rpm, especially screw-type and roots type blowers.
Efficiency
This is the turbo's biggest advantage. The turbocharger is generally more economical to operate as it as it is driven primarily by potential energy in the exhaust gasses that would otherwise be lost out the exhaust, whereas a supercharger draws power from the crank, which can be used to turn the wheels. The turbocharger's impeller is also powered only under boost conditions, so there is less parasitic drag while the impeller is not spinning. The turbocharger, however, is not free of inefficiency as it does create additional exhaust backpressure and exhaust flow interruption.
Heat
Because the turbocharger is mounted to the exhaust manifold (which is very hot), turbocharger boost is subject to additional heating via the turbo's hot casing. Because hot air expands (the opposite goal of a turbo or supercharger), an intercooler becomes necessary on almost all turbocharged applications to cool the air charge before it is released into the engine. This increases the complexity of the installation. A centrifugal supercharger on the other hand creates a cooler air discharge, so an intercooler is often not necessary at boost levels below 10psi. That said, some superchargers (especially roots-type superchargers) create hotter discharge temperatures, which also make an intecooler necessary even on fairly low-boost applications.
Surge
Because a turbocharger first spools up before the boost is delivered to the engine, there is a surge of power that is delivered immediately when the wastegate opens (around 3000 rpm). This surge can be damaging to the engine and drivetrain, and can make the vehicle difficult to drive or lose traction.
Back Pressure
Because the supercharger eliminates the need to deal with the exhaust gas interruption created by inserting a turbocharger turbine into the exhaust flow, the supercharger creates no additional exhaust backpressure. The amount of power that is lost by a turbo's turbine reduces it's overall efficiency.
Noise
The turbocharger is generally quiter than the supercharger. Because the turbo's turbine is in the exhaust, the turbo can substantially reduce exhaust noise, making the engine run quieter. Some centrifugal superchargers are known to be noisy and whistley which, annoys some drivers (we, however, love it!)
Reliability
In general, superchargers enjoy a substantial reliability advantage over the turbocharger. When a a turbo is shut off (i.e. when the engine is turned off), residual oil inside the turbo's bearings can be baked by stored engine heat. This, combined with the turbo's extremely high rpms (up to 150,000rpm) can cause problems with the turbo's internal bearings and can shorten the life of the turbocharger. In addition, many turbos require aftermarket exhaust manifolds, which are often far less reliable than stock manifolds.
Ease of Installation
Superchargers are substantially easier to install than a turbos because they have far fewer components and simpler devices. Turbos are complex and require manifold and exhaust modifications, intercoolers, extra oil lines, etc. - most of which is not needed with most superchargers. A novice home mechanic can easily install most supercharger systems, while a turbo installation should be left to a turbo expert.
Maximum Power Output
Turbos are known for their unique ability to spin to incredibly high rpms and make outrages peak boost figures (25psi+). While operating a turbocharger at very high levels of boost requires major modifications to the rest of the engine, the turbo is capable of producing more peak power than superchargers.
Tunability
Turbochargers, because they are so complex and rely on exhaust pressure, are notoriously difficult to tune. Superchargers, on the other hand, require few fuel and ignition upgrades and normally require little or no engine tuning.
Conclusion
While the supercharger is generally considered to be a better method of forced induction for most street and race vehicles, the turbo will always have its place in a more specialized market. Superchargers generally provide a much broader powerband that most drivers are looking for with no "turbo lag". In addition, they are much easier to install and tune, making them more practical for a home or novice mechanic.
and here's something from howstuffworks.com
What is the difference between a turbocharger and a supercharger on a car's engine?
Let's start with the similarities. Both turbochargers and superchargers are called forced induction systems. They compress the air flowing into the engine (see How Car Engines Work for a description of airflow in a normal engine). The advantage of compressing the air is that it lets the engine stuff more air into a cylinder. More air means that more fuel can be stuffed in, too, so you get more power from each explosion in each cylinder. A turbo/supercharged engine produces more power overall than the same engine without the charging.
The typical boost provided by either a turbocharger or a supercharger is 6 to 8 pounds per square inch (psi). Since normal atmospheric pressure is 14.7 psi at sea level, you can see that you are getting about 50-percent more air into the engine. Therefore, you would expect to get 50-percent more power. It's not perfectly efficient, though, so you might get a 30-percent to 40-percent improvement instead.
The key difference between a turbocharger and a supercharger is its power supply. Something has to supply the power to run the air compressor. In a supercharger, there is a belt that connects directly to the engine. It gets its power the same way that the water pump or alternator does. A turbocharger, on the other hand, gets its power from the exhaust stream. The exhaust runs through a turbine, which in turn spins the compressor (see How Gas Turbine Engines Work for details).
There are tradeoffs in both systems. In theory, a turbocharger is more efficient because it is using the "wasted" energy in the exhaust stream for its power source. On the other hand, a turbocharger causes some amount of back pressure in the exhaust system and tends to provide less boost until the engine is running at higher RPMs. Superchargers are easier to install but tend to be more expensive.
Cost
The cost of supercharger and a turbocharger systems for the same engine are approximately the same, so cost is generally not a factor.
Lag
This is perhaps the biggest advantage that the supercharger enjoys over the tubo. Because a turbocharger is driven by exhaust gasses, the turbocharger's turbine must first spool up before it even begins to turn the compressor's impeller. This results in lag time which is the time needed for the turbine to reach its full throttle from an intermediate rotational speed state. During this lag time, the turbocharger is creating little to no boost, which means little to no power gains during this time. Smaller turbos spool up quicker, which eliminates some of this lag. Turbochargers thus utilize a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses boost pressure, and if it gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down..
A Supercharger, on the other hand, is connected directly to the crank, so there is no "lag". Superchargers are able to produce boost at a very low rpm, especially screw-type and roots type blowers.
Efficiency
This is the turbo's biggest advantage. The turbocharger is generally more economical to operate as it as it is driven primarily by potential energy in the exhaust gasses that would otherwise be lost out the exhaust, whereas a supercharger draws power from the crank, which can be used to turn the wheels. The turbocharger's impeller is also powered only under boost conditions, so there is less parasitic drag while the impeller is not spinning. The turbocharger, however, is not free of inefficiency as it does create additional exhaust backpressure and exhaust flow interruption.
Heat
Because the turbocharger is mounted to the exhaust manifold (which is very hot), turbocharger boost is subject to additional heating via the turbo's hot casing. Because hot air expands (the opposite goal of a turbo or supercharger), an intercooler becomes necessary on almost all turbocharged applications to cool the air charge before it is released into the engine. This increases the complexity of the installation. A centrifugal supercharger on the other hand creates a cooler air discharge, so an intercooler is often not necessary at boost levels below 10psi. That said, some superchargers (especially roots-type superchargers) create hotter discharge temperatures, which also make an intecooler necessary even on fairly low-boost applications.
Surge
Because a turbocharger first spools up before the boost is delivered to the engine, there is a surge of power that is delivered immediately when the wastegate opens (around 3000 rpm). This surge can be damaging to the engine and drivetrain, and can make the vehicle difficult to drive or lose traction.
Back Pressure
Because the supercharger eliminates the need to deal with the exhaust gas interruption created by inserting a turbocharger turbine into the exhaust flow, the supercharger creates no additional exhaust backpressure. The amount of power that is lost by a turbo's turbine reduces it's overall efficiency.
Noise
The turbocharger is generally quiter than the supercharger. Because the turbo's turbine is in the exhaust, the turbo can substantially reduce exhaust noise, making the engine run quieter. Some centrifugal superchargers are known to be noisy and whistley which, annoys some drivers (we, however, love it!)
Reliability
In general, superchargers enjoy a substantial reliability advantage over the turbocharger. When a a turbo is shut off (i.e. when the engine is turned off), residual oil inside the turbo's bearings can be baked by stored engine heat. This, combined with the turbo's extremely high rpms (up to 150,000rpm) can cause problems with the turbo's internal bearings and can shorten the life of the turbocharger. In addition, many turbos require aftermarket exhaust manifolds, which are often far less reliable than stock manifolds.
Ease of Installation
Superchargers are substantially easier to install than a turbos because they have far fewer components and simpler devices. Turbos are complex and require manifold and exhaust modifications, intercoolers, extra oil lines, etc. - most of which is not needed with most superchargers. A novice home mechanic can easily install most supercharger systems, while a turbo installation should be left to a turbo expert.
Maximum Power Output
Turbos are known for their unique ability to spin to incredibly high rpms and make outrages peak boost figures (25psi+). While operating a turbocharger at very high levels of boost requires major modifications to the rest of the engine, the turbo is capable of producing more peak power than superchargers.
Tunability
Turbochargers, because they are so complex and rely on exhaust pressure, are notoriously difficult to tune. Superchargers, on the other hand, require few fuel and ignition upgrades and normally require little or no engine tuning.
Conclusion
While the supercharger is generally considered to be a better method of forced induction for most street and race vehicles, the turbo will always have its place in a more specialized market. Superchargers generally provide a much broader powerband that most drivers are looking for with no "turbo lag". In addition, they are much easier to install and tune, making them more practical for a home or novice mechanic.
and here's something from howstuffworks.com
What is the difference between a turbocharger and a supercharger on a car's engine?
Let's start with the similarities. Both turbochargers and superchargers are called forced induction systems. They compress the air flowing into the engine (see How Car Engines Work for a description of airflow in a normal engine). The advantage of compressing the air is that it lets the engine stuff more air into a cylinder. More air means that more fuel can be stuffed in, too, so you get more power from each explosion in each cylinder. A turbo/supercharged engine produces more power overall than the same engine without the charging.
The typical boost provided by either a turbocharger or a supercharger is 6 to 8 pounds per square inch (psi). Since normal atmospheric pressure is 14.7 psi at sea level, you can see that you are getting about 50-percent more air into the engine. Therefore, you would expect to get 50-percent more power. It's not perfectly efficient, though, so you might get a 30-percent to 40-percent improvement instead.
The key difference between a turbocharger and a supercharger is its power supply. Something has to supply the power to run the air compressor. In a supercharger, there is a belt that connects directly to the engine. It gets its power the same way that the water pump or alternator does. A turbocharger, on the other hand, gets its power from the exhaust stream. The exhaust runs through a turbine, which in turn spins the compressor (see How Gas Turbine Engines Work for details).
There are tradeoffs in both systems. In theory, a turbocharger is more efficient because it is using the "wasted" energy in the exhaust stream for its power source. On the other hand, a turbocharger causes some amount of back pressure in the exhaust system and tends to provide less boost until the engine is running at higher RPMs. Superchargers are easier to install but tend to be more expensive.
01-14-2005, 10:43 PM
#15
Senior Member
SL Member
Join Date: Oct 2004
Location: Florence Scion (SC)
Posts: 208
2 Errors in the original post:
1) Most turbos are oil cooled, not water cooled. This is why after hard driving you need to idle the car for a few mins so the hot oil have cool down and leave the turbo. Hot oil will cool too quickly and turn solid in the turbo.
2) Turbos can boost well over 21 psi. On a drag car they make between 35-40 psi. On a diesel motor they can make upwards of 70 psi.
1) Most turbos are oil cooled, not water cooled. This is why after hard driving you need to idle the car for a few mins so the hot oil have cool down and leave the turbo. Hot oil will cool too quickly and turn solid in the turbo.
2) Turbos can boost well over 21 psi. On a drag car they make between 35-40 psi. On a diesel motor they can make upwards of 70 psi.
01-15-2005, 06:54 AM
#17
Senior Member
SL Member
Join Date: Dec 2004
Posts: 119
Originally Posted by florencescion
2 Errors in the original post:
1) Most turbos are oil cooled, not water cooled. This is why after hard driving you need to idle the car for a few mins so the hot oil have cool down and leave the turbo. Hot oil will cool too quickly and turn solid in the turbo.
2) Turbos can boost well over 21 psi. On a drag car they make between 35-40 psi. On a diesel motor they can make upwards of 70 psi.
1) Most turbos are oil cooled, not water cooled. This is why after hard driving you need to idle the car for a few mins so the hot oil have cool down and leave the turbo. Hot oil will cool too quickly and turn solid in the turbo.
2) Turbos can boost well over 21 psi. On a drag car they make between 35-40 psi. On a diesel motor they can make upwards of 70 psi.
Florence my only turbo experience comes from Saab (9000 AERO and 95 AERO)
and to the best of my knowledge all SAAB trurbos are now watercooled hence no need, at least in theory, for a cool down (I would still do it remebereing this nice glow yo get under the hood after 100 miles)
Saabs are pretty much the first production cars in the world equipped with turbo so I would think they they have experience in implementing trubo on passenger cars...
Anyways, one of the biggest advantages of Saabs is their propiretary engine mamnagement (Trionic Ecopower) system that was designed to support turbo (i.e. ECU controlls wastegate and by-pass making it a part of the algorhitm).
That's also why I question addon turbo kits since turbo app with a significant boost requiers upgraded (more pressure) fuele delivery and redisigned ECU algorithms...
How do you deal with that on an add-on turbo kit?
I am going to leave this discussion as I already made up my mind, I would rather have a warranty covered and factory tested although less performing s/c than risk
the powertrain by installing aftermarket turbo on an engine that was simply not designed to be abused that way. Remember where this engine is coming from....
Yes trubos ca boost. The question is how is the powertrain going to take it?
BTW, Wanna turbo? Buy an S4...
01-15-2005, 09:06 AM
#18
Junior Member
Join Date: Jan 2005
Location: Vista, CA
Posts: 8
Re: truth about sc vs tc
Originally Posted by ICLUB2
They must be fitted as close as possible to the head.
Originally Posted by ICLUB2
TC's must run very hot, just short of melting down. This requires that the surrounding of the TC must be well insulated from radiation heat, and that the engine must be kept idling for a minute or two after heavy use before switching off. Obviously, the turbo is water-cooled.
Originally Posted by ICLUB2
TC's must run hot because they rely on the exhaust gas velocity, which is directly proportional to the temperature.
Originally Posted by ICLUB2
TC's have turbo lag, the time it takes to wind the "fan" up. This is less noticeable with automatics or during manual gear shift, but very noticeable during a "standing start".
Originally Posted by ICLUB2
TC's are more commonly used in diesel engines.
Originally Posted by ICLUB2
TC's are used more frequently in Europe because smaller engines (4 cylinders) are more common.
Originally Posted by ICLUB2
TC's require a special exhaust branch, which must be made of high temperature material, if possible with no heat expansion ! Otherwise your exhaust branch gasket will not last.
Originally Posted by ICLUB2
You can fit two TC's on a V6 or V8, it works. But you must choose the TC carefully, and you have twice the radiation heat problem, twice the cost.
Originally Posted by ICLUB2
SC's are used exclusively in acceleration racing, because the turbo lag can't be tolerated.
Originally Posted by ICLUB2
Depending on the type of SC you are considering, the fitting varies from being outright impossible to easy as fitting an air-conditioner pump.
Originally Posted by ICLUB2
TC's are used on constant load engines such as trucks, marine engines and power-plants.
Originally Posted by ICLUB2
There are many types of SC's, but only one type TC. The selection of the correct size and manufacturer of either TC or SC is an art, which should be left to the experts. Many technical books have been written about it and free advice is available from the manufacturers of TC's or SC's.
Originally Posted by ICLUB2
When you look at the boost pressure curve of TC's and SC's, the SC's don't look too impressive. This is because they have to be geared to produce the maximum boost pressure at high RPM. In comparison, a TC has a regulation device built in, which opens a "waste gate" once the maximum boost has been reached. The TC curve doesn't explain the turbo lag!
Originally Posted by ICLUB2
A TC produces more power at low RPM, because a well selected TC produces the maximum boost between 1500 to 2500 RPM, when the waste gate starts to open. This operating mode may be useful for 4x4's. In the latest TC design, the turbo's fan's became smaller, the waste gate bigger, and the turbo speed higher.
Originally Posted by ICLUB2
TC's can't really produce very high boost pressure, above 1.5 bar (21 psi). Someone will prove me wrong, I am sure. But TC's are used normally between 0.4 to 1.2 bar (6 psi to 17 psi).
Originally Posted by ICLUB2
Another way to explain the turbo lag: A TC works on the chain reaction principle, it is the starting of the chain which produces the lag. Lets assume the engine idles and so does the turbo. The boost pressure is ZERO. Then you open the throttle to a particular point and keep it there. The engine operates in a decompressed state and produces very little power. The little power it makes raises the exhaust gas temperature and velocity. This makes the turbo spin a little faster and raises the boost pressure, which in turn makes a little more power, which in turn.....(the chain reaction sets in). The chain reaction is limited by the waste gate regulation, and the airflow through your butterflies. Also, the TC can limit the boost pressure, or RPM limits can come in, or your engine blows up.
Originally Posted by ICLUB2
SC's are more predictable in engineering terms. From the manufacturers data you can choose the correct gearing for the desired boost pressure and RPM.
Originally Posted by ICLUB2
SC's are more expensive and difficult to manufacture.
Originally Posted by ICLUB2
SC's are heating the boost air to the same extent as TC's, but the fitting of intercoolers is hardly every done to the roots type.
Originally Posted by ICLUB2
Summary: If you have a straight engine, not used in a dragster, consider a TC: it's less expensive, but requires a little engineering. Otherwise look at a SC. Make a market research as to the types, size, lubrication, cooling and gearing required. If you are building dragsters, it must be a SC, and your choices are limited to two or three manufacturers, which are helpful in providing kits and free advice.
sorry its so long, lol!
sorry its so long, lol!
now let me say that i am not an expert on this subject but did my best to relay what i believe to be correct information that i have collected from being into forced induction hondas for the last four years or so. you might have been able to tell by reading my post that i don't care for the term "turbo lag" and the way that it is commonly used as i do not feel like it is correct. i am also bias to turbochargers because through my research it is what i believe to be the most appropriate for any application i have ever been interested in.
i also want to take this chance to say hi to everybody. i'm new to scionlife and am contemplating purchacing a tc and have been browsing these forums for quite some time but have just started posting today.
sorry to the original posted for the times that i was rude in my post, it was just a bit frustrating at times. please don't be hardheaded and do absorb the information in this thread.
no hard feelings
.if anybody feels that any of this information is incorrect please post your argument. i, like everybody else on here, am here to learn. thanks.
01-15-2005, 09:14 AM
#19
Junior Member
Join Date: Jan 2005
Location: Vista, CA
Posts: 8
Originally Posted by Stefan TC
That's also why I question addon turbo kits since turbo app with a significant boost requiers upgraded (more pressure) fuele delivery and redisigned ECU algorithms...
How do you deal with that on an add-on turbo kit?
How do you deal with that on an add-on turbo kit?
in addition to the solutions listed above, there are many aftermarket stand alone fuel management systems that completely replace the ecu like the aem ems, motec, haltech as well as endless others.
