AVC-R for bost control
04-19-04, 10:59 PM
#1
What's an RX-7 ?
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AVC-R for bost control
Well I was wondering if I can hook up my avc-r to only control secondary boost instead of hooking it in as the directions show controlling both pre-spool and boost. Im only getting boost creep above 5000rpm, and I know hooking it up the way the manual says doesnt work well for many people. So all I really need it to do is control my secondary boost right ? Is this possible and how would I hook it up ?
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04-21-04, 11:33 PM
#8
addicted to lounge
spikes...not creep...I actually don't think there is that much knowledge on this forum about that specific controller. I have it too and didn't get much help from this forum...that was a couple of years ago though
04-22-04, 12:53 AM
#9
Yellow Dragon is no more
You can do what you stated to help with transistion, but it will not help with creep just as Damon stated. On WIDE open exhaust and non-ported wastegate 15psi is just the begining. You are likely to keep going to 17 or 18 psi. 
04-22-04, 03:37 PM
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I didnt know this either, No it seems when it creeps I should only see 14psi but it creeps up to 16psi at WOT and then I hit fuel cut... Maybe it will help though, do you think I should try hooking it up or should I restrict my exhaust flow a little bit instead and see if the PFC will control it better then ?
04-22-04, 03:57 PM
#12
Lives on the Forum
You have to understand the difference between boost creep and overboosting.
Boost is controlled by the wastegate on the turbo. The farther you open the wastegate the more exhaust you divert from the turbo and the less boost the turbo will make. A boost controller is used to control the wastegate and thus control boost; as boost climbs to the preset level the wastegate is opened more and more to control maximum boost. Boost controllers work great at this.
Boost creep happens when the wastegate is already fully open but (on our cars) due to mods like intake, downpipe, catback and/or midpipe the airflow through the motor is so great that the exhaust volume can completely overwhelm the wastegate. Even though the wastegate is fully open there is enough exhaust volume left to still overrun the turbo and the turbo will continue to build boost even though our control system is trying to prevent any more boost from building. Once you have creep a boost controller cannot help you because all it does is open the wastegate. Once the wastegate is fully open and the turbo is still building boost there is nothing more a boost controller can do to save you.
We'll let a funnel represent the wastegate and we'll pour water through it which represents the exhaust flow. We can dump water into the funnel and it will spill out the bottom as long as we do not dump the water in faster than the hole in the bottom of the funnel can let it out. Once we add water too quickly we will begin to fill the funnel with water until it then overflows. The hole in the funnel is still draining water but it can't drain it quickly enough. This is exactly what happens to your wastegate if you have boost creep; it can't bleed the excess exhaust off quickly enough and so boost continues to rise.
Boost creep is what happens when your wastegate "hole" is not big enough. To prevent boost creep you can make the wastegate bigger so it will flow greater volume ("porting the wastegate" on the stock twins will solve most cases) or you can somehow impede the airflow through the turbos by making the intake less efficient so less air is drawn into the motor or by adding a restriction to the exhaust so exhaust gases cannot flow out of the motor as easily. Either of this will decrease the amount of exhaust volume available and so slow the turbo.
Boost is controlled by the wastegate on the turbo. The farther you open the wastegate the more exhaust you divert from the turbo and the less boost the turbo will make. A boost controller is used to control the wastegate and thus control boost; as boost climbs to the preset level the wastegate is opened more and more to control maximum boost. Boost controllers work great at this.
Boost creep happens when the wastegate is already fully open but (on our cars) due to mods like intake, downpipe, catback and/or midpipe the airflow through the motor is so great that the exhaust volume can completely overwhelm the wastegate. Even though the wastegate is fully open there is enough exhaust volume left to still overrun the turbo and the turbo will continue to build boost even though our control system is trying to prevent any more boost from building. Once you have creep a boost controller cannot help you because all it does is open the wastegate. Once the wastegate is fully open and the turbo is still building boost there is nothing more a boost controller can do to save you.
We'll let a funnel represent the wastegate and we'll pour water through it which represents the exhaust flow. We can dump water into the funnel and it will spill out the bottom as long as we do not dump the water in faster than the hole in the bottom of the funnel can let it out. Once we add water too quickly we will begin to fill the funnel with water until it then overflows. The hole in the funnel is still draining water but it can't drain it quickly enough. This is exactly what happens to your wastegate if you have boost creep; it can't bleed the excess exhaust off quickly enough and so boost continues to rise.
Boost creep is what happens when your wastegate "hole" is not big enough. To prevent boost creep you can make the wastegate bigger so it will flow greater volume ("porting the wastegate" on the stock twins will solve most cases) or you can somehow impede the airflow through the turbos by making the intake less efficient so less air is drawn into the motor or by adding a restriction to the exhaust so exhaust gases cannot flow out of the motor as easily. Either of this will decrease the amount of exhaust volume available and so slow the turbo.
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