STS Spool time
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On The Tree
Joined: Jun 2005
Posts: 119
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Originally Posted by 300bhp/ton
Not sure what you're asking here, but people seem to be answering a different question, but maybe that is really what you wanted to know. 
You asked how long it takes to spool. This evidently would be time based, so it therefore would not be referring to the point in the rpms where boost is made, as this isn't time based.
Spool time would be LAG, which all turbocharged cars suffer from, unless running an Anti-lag System (ALS). LAG occurs after a stall period. This is when the throttle plate on the TB is closed, the exhaust gas velocity reduces stalling the turbine, combine this with the trapped high pressure air beteen the turbocharger and the TB it causes the turbine to stall. When you re-open the throttle plate, the exhaust gas flow will increase, but there will be a momentary LAG before boost is produced, this is becuase a turbocharger has to spin at a very high rpm to produce boost. A BOV or dump valve releases the trapped air pressure air, helping to minimise the stall, but exhaust gas flow is the primary culprit.
Remember ALL turbocharged engines suffer from this. Good location and well matched turbo's mean you should be able to reduce LAG to a minimum, but it will still be present.
I don't have any times for LAG, but when I spoke to an STS agent about LAG they would always sidestep the question, that combined with other comments I have read and just plain physics means I would not entertain a rear mount setup unless the car is soley for dyno numbers and straight line drag racing, if you like driving road courses it is far from ideal.
LAG can and will occur at any point within the operation boost range of the turbo. So even though it may be able to produce boost at 2500rpm and max boost by 3000rpm. If you lift off the throttle at 5200rpm for a second (cornering) and then reapply the throttle you will have LAG even though the rpm's may not have dropped below 4500rpm.
If you want the best throttle response you'll want twin turbo's mounted where they should be in the engine bay. Twins allow you to run smaller turbo's so in theory they should require less exhaust gas flow to produce boost, this means the LAG period would be reduced. Although I believe (not sure for certain) that some of the fastest and most powerful turbo cars usually use a large single turbo as it is more efficent.
-Positive Displacement supercharger offers the best throttle response and no lag.
-Centrifugal supercharger offers minimal lag. But it does contain some, again due to the high rpm's that the blower runs at to produce boost. However low end torque is comparatively poor.
-Front mount turbo. Most efficent and will produce the most power. A well sorted setup should offer good driveability but LAG will be present.
-Rear mount turbo will still be more efficent than a supercharger and thus produce more power but LAG and throttle response will be worse than any of the other options.
For straight line use probably yes. But remember without load on the engine the turbo will not be producing boost. If you rev the car in neutral the boost gage should not move.
Just my 2 pennies worth.
You asked how long it takes to spool. This evidently would be time based, so it therefore would not be referring to the point in the rpms where boost is made, as this isn't time based.
Spool time would be LAG, which all turbocharged cars suffer from, unless running an Anti-lag System (ALS). LAG occurs after a stall period. This is when the throttle plate on the TB is closed, the exhaust gas velocity reduces stalling the turbine, combine this with the trapped high pressure air beteen the turbocharger and the TB it causes the turbine to stall. When you re-open the throttle plate, the exhaust gas flow will increase, but there will be a momentary LAG before boost is produced, this is becuase a turbocharger has to spin at a very high rpm to produce boost. A BOV or dump valve releases the trapped air pressure air, helping to minimise the stall, but exhaust gas flow is the primary culprit.
Remember ALL turbocharged engines suffer from this. Good location and well matched turbo's mean you should be able to reduce LAG to a minimum, but it will still be present.
I don't have any times for LAG, but when I spoke to an STS agent about LAG they would always sidestep the question, that combined with other comments I have read and just plain physics means I would not entertain a rear mount setup unless the car is soley for dyno numbers and straight line drag racing, if you like driving road courses it is far from ideal.
LAG can and will occur at any point within the operation boost range of the turbo. So even though it may be able to produce boost at 2500rpm and max boost by 3000rpm. If you lift off the throttle at 5200rpm for a second (cornering) and then reapply the throttle you will have LAG even though the rpm's may not have dropped below 4500rpm.
If you want the best throttle response you'll want twin turbo's mounted where they should be in the engine bay. Twins allow you to run smaller turbo's so in theory they should require less exhaust gas flow to produce boost, this means the LAG period would be reduced. Although I believe (not sure for certain) that some of the fastest and most powerful turbo cars usually use a large single turbo as it is more efficent.
-Positive Displacement supercharger offers the best throttle response and no lag.
-Centrifugal supercharger offers minimal lag. But it does contain some, again due to the high rpm's that the blower runs at to produce boost. However low end torque is comparatively poor.
-Front mount turbo. Most efficent and will produce the most power. A well sorted setup should offer good driveability but LAG will be present.
-Rear mount turbo will still be more efficent than a supercharger and thus produce more power but LAG and throttle response will be worse than any of the other options.
For straight line use probably yes. But remember without load on the engine the turbo will not be producing boost. If you rev the car in neutral the boost gage should not move.
Just my 2 pennies worth.
Thanks for you 2 pennies but basically what you said was I dont like sts kits....and talked about stuff that I already new....
but....
Someone did make a point that I should of asked how fast do you spool up into the positive boost?
Originally Posted by Bankz27
Thanks for you 2 pennies but basically what you said was I dont like sts kits....and talked about stuff that I already new....
but....
Someone did make a point that I should of asked how fast do you spool up into the positive boost?
but....
Someone did make a point that I should of asked how fast do you spool up into the positive boost?
No lag at all and they make more power than any other FI kit could possibly make. Once the Civics start running them, we all need to watch the fu@k out!
TECH Apprentice
Joined: Jan 2004
Posts: 337
Likes: 0
From: Frisco TX (Dallas Area)
Originally Posted by Wet 1
You sound like a perfect fit for a STS kit!
No lag at all and they make more power than any other FI kit could possibly make. Once the Civics start running them, we all need to watch the fu@k out!
No lag at all and they make more power than any other FI kit could possibly make. Once the Civics start running them, we all need to watch the fu@k out!
To answer the questions about length of vacuum line reference to the wastegate, just do like I did and run metal brake lines for the main lengths instead of rubber line. You eliminate the soft line expansion under pressure. I did that because if I run the reference to the wastegate before the fmic, I don't get the full pressure from the manifold because of the pressure drop through the intercooler. This ends up leading to several feet of vacuum line going from the intake manifold to the boost controller to the wastegate on the sts. The time it takes to pressurize small diameter hard brake line is negligible, even over runs of several feet instead of inches.
Originally Posted by Wet 1
You sound like a perfect fit for a STS kit!
No lag at all and they make more power than any other FI kit could possibly make. Once the Civics start running them, we all need to watch the fu@k out!
No lag at all and they make more power than any other FI kit could possibly make. Once the Civics start running them, we all need to watch the fu@k out!
