Kane
01-29-2010, 10:28 AM
Well; I finally decided to sit down and bang out some more info for everyone.
I did not get pics and video of the Boost Controller tuning I did in Seattle due to being distracted by dyno drama - but I think I can still get the gist out.
The first thing is to understand how a boost controller works; in simple terms it will hold back or modify the boost signal to the turbo wastegate to increase boost. Keep in mind that you can not go lower than your wastegate spring setting (except for an incorrectly set-up BC on an external wastegate). The issue with a factory wastegate spring set-up is that while the spring may be rated to say 10 PSI; that means the wastegate is fully open at 10 PSI; since it is operated by a diaphragm (mostly) the actuator arm will start to move much earlier than 10 PSI - as much as 5-6 PSI early it will have already cracked the wastgate and will be bleeding exhaust by the turbine a lot earlier than you want it to. If you want 10 PSI; then you want to get to 10 PSI as fast as possible without spiking the boost PAST 10 PSI.
Ok; so how can an EBC help us do this? Quite simply, you want to avoid sending ANY signal to the wastegate until the last possible moment. One of the typical faults of BC tuning is that people try to increase the overall amount of boost first - instead of setting up the starting boost threshold first.
So we know basically what we want to do - now how do we go about it?
MANUAL
One of the cheapest and easiest way's to increase the boost threshold is by making a mechanical change to the Wastegate and Actuator. By increasing the tension applied to the WG door - you can push the boost curve to the right (see picture); the shape of the curve will remain relatively the same. Swapping the Wastegate spring with a stiffer one (if applicable) will have similar effects. Ideally; you want the curve as close to the red line as possible. Manual Boost Controllers are IMO a waste of time and fairly un-tunable, so I won't discuss them here much; basically they do the same things as other manual methods of boost control...for more money.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/wategatesettings.gif
ELECTRONIC
There are as many terms and settings as there are Electronic Boost Controllers; so read your instructions thoroughly; I'll use the terms for the Greddy series of EBC's. In most cases you have three BASIC settings; Start Boost, Gain and Set Boost. Each of these settings has an impact on your boost curve.
RULE 1: TUNE ONE SETTING AT A TIME!!! You cannot measure what changes were made if you are working with multiple variables. Tune one setting at a time until you get the best boost curve you can.
RULE 2: AIM SMALL; MISS SMALL!!! To avoid over boosting and wrecking your motor or turbo, make small changes as you progress and don't get impatient. This can take anywhere from 30-45 minutes to an entire day.
RULE 3: MEASURE EVERYTHING!!! If you cannot log your boost curve, then this exercise is useless; so get a boost gauge or log on your MAP based EMS curve... or SOMETHING!!! But you need to compare your boost curves as you tune.
Ok, on to the fun stuff.
Start Boost - this is the setting that controls how long your BC will send NO signal to the wastegate. IE; how long the wastegate will remain totally closed. This is the key setting for me.
Gain - Gain, or Duty Cycle or whatever; is how fast the solenoid on the BC will cycle, this is important because if your BC is cycling too slowly you can get boost fall off before it re-adjusts itself. Similarly, if the Duty Cycle is too high, you can get boost spikes.
Set - Set, Set Gain, Target Boost etc; is how high the BC will allow you to build pressure into the intake manifold by controlling the amount of signal boost being sent to the wastegate. This setting along with gain are what I tune together to fine tune the overall boost curve.
So; with my fully tuned vehicle in good mechanical order, I first ensure that I have enough fueling and headroom in my tune to get higher boost numbers. If not I make sure that I do... I NEVER tune a BC if I am on the ragged edge with just the Wastegate... a few pounds of boost is not worth a motor.
Then on a level, slightly inclined grade or dyno I begin tuning by getting a baseline boost curve from just the Wastegate. This will allow me to see what changes I am making to the curve.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/slide1.gif
Then I adjust the Start Boost until I peak at the target PSI, without going over... while it might look like a boost spike, it is not a spike UNLESS I overshoot my target boost. If I do, then I just need to lower the start boost level.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/slide2.gif
Once I have reached my target boost level; I then turn up the set value until I can hold the target boost level for as long as I can. The trick here is that IF I go past my target boost level I know my set value is too high, and the rest of my changes much be to the gain of the BC. Typically you see boost fade with all set and no gain.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/slide3.gif
Finally, add in my gain duty cycle to hold the boost level through the power band as best as possible.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/slide4.gif
In a nutshell that is about it. Now based on the size of your turbo and the trims, your curves will not look exactly the same (IE big turbo's take longer to spool no matter what). But the shapes are generally going to be correct. Also, if the compressor is too small - no matter what you may get boost fall off at high RPM.
If you have a low and high setting; or you are ready to increase your boost... use these "low" settings and adjust your set first to get your target boost, and then go back to start boost. This helps to avoid a boost spike if you are only making small changes to the target boost.
I did not get pics and video of the Boost Controller tuning I did in Seattle due to being distracted by dyno drama - but I think I can still get the gist out.
The first thing is to understand how a boost controller works; in simple terms it will hold back or modify the boost signal to the turbo wastegate to increase boost. Keep in mind that you can not go lower than your wastegate spring setting (except for an incorrectly set-up BC on an external wastegate). The issue with a factory wastegate spring set-up is that while the spring may be rated to say 10 PSI; that means the wastegate is fully open at 10 PSI; since it is operated by a diaphragm (mostly) the actuator arm will start to move much earlier than 10 PSI - as much as 5-6 PSI early it will have already cracked the wastgate and will be bleeding exhaust by the turbine a lot earlier than you want it to. If you want 10 PSI; then you want to get to 10 PSI as fast as possible without spiking the boost PAST 10 PSI.
Ok; so how can an EBC help us do this? Quite simply, you want to avoid sending ANY signal to the wastegate until the last possible moment. One of the typical faults of BC tuning is that people try to increase the overall amount of boost first - instead of setting up the starting boost threshold first.
So we know basically what we want to do - now how do we go about it?
MANUAL
One of the cheapest and easiest way's to increase the boost threshold is by making a mechanical change to the Wastegate and Actuator. By increasing the tension applied to the WG door - you can push the boost curve to the right (see picture); the shape of the curve will remain relatively the same. Swapping the Wastegate spring with a stiffer one (if applicable) will have similar effects. Ideally; you want the curve as close to the red line as possible. Manual Boost Controllers are IMO a waste of time and fairly un-tunable, so I won't discuss them here much; basically they do the same things as other manual methods of boost control...for more money.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/wategatesettings.gif
ELECTRONIC
There are as many terms and settings as there are Electronic Boost Controllers; so read your instructions thoroughly; I'll use the terms for the Greddy series of EBC's. In most cases you have three BASIC settings; Start Boost, Gain and Set Boost. Each of these settings has an impact on your boost curve.
RULE 1: TUNE ONE SETTING AT A TIME!!! You cannot measure what changes were made if you are working with multiple variables. Tune one setting at a time until you get the best boost curve you can.
RULE 2: AIM SMALL; MISS SMALL!!! To avoid over boosting and wrecking your motor or turbo, make small changes as you progress and don't get impatient. This can take anywhere from 30-45 minutes to an entire day.
RULE 3: MEASURE EVERYTHING!!! If you cannot log your boost curve, then this exercise is useless; so get a boost gauge or log on your MAP based EMS curve... or SOMETHING!!! But you need to compare your boost curves as you tune.
Ok, on to the fun stuff.
Start Boost - this is the setting that controls how long your BC will send NO signal to the wastegate. IE; how long the wastegate will remain totally closed. This is the key setting for me.
Gain - Gain, or Duty Cycle or whatever; is how fast the solenoid on the BC will cycle, this is important because if your BC is cycling too slowly you can get boost fall off before it re-adjusts itself. Similarly, if the Duty Cycle is too high, you can get boost spikes.
Set - Set, Set Gain, Target Boost etc; is how high the BC will allow you to build pressure into the intake manifold by controlling the amount of signal boost being sent to the wastegate. This setting along with gain are what I tune together to fine tune the overall boost curve.
So; with my fully tuned vehicle in good mechanical order, I first ensure that I have enough fueling and headroom in my tune to get higher boost numbers. If not I make sure that I do... I NEVER tune a BC if I am on the ragged edge with just the Wastegate... a few pounds of boost is not worth a motor.
Then on a level, slightly inclined grade or dyno I begin tuning by getting a baseline boost curve from just the Wastegate. This will allow me to see what changes I am making to the curve.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/slide1.gif
Then I adjust the Start Boost until I peak at the target PSI, without going over... while it might look like a boost spike, it is not a spike UNLESS I overshoot my target boost. If I do, then I just need to lower the start boost level.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/slide2.gif
Once I have reached my target boost level; I then turn up the set value until I can hold the target boost level for as long as I can. The trick here is that IF I go past my target boost level I know my set value is too high, and the rest of my changes much be to the gain of the BC. Typically you see boost fade with all set and no gain.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/slide3.gif
Finally, add in my gain duty cycle to hold the boost level through the power band as best as possible.
http://ppo2performance.com/docs/wp-content/uploads/2009/09/slide4.gif
In a nutshell that is about it. Now based on the size of your turbo and the trims, your curves will not look exactly the same (IE big turbo's take longer to spool no matter what). But the shapes are generally going to be correct. Also, if the compressor is too small - no matter what you may get boost fall off at high RPM.
If you have a low and high setting; or you are ready to increase your boost... use these "low" settings and adjust your set first to get your target boost, and then go back to start boost. This helps to avoid a boost spike if you are only making small changes to the target boost.