electronic boost control.
 

I've never really delved into eletronic boost level controllers and I wanted to make sure my understanding of how it works is correct.

If I'm understanding it right, say you have a bypass valve built onto the turbo that defaults at 7psi. The electronic controller is told what the default spring is and then when you tell it that you want say 11 psi at 6500 rpms. the controller will restrict flow from the Manifold pressure feed so that the turbo bypass valve thinks it's only seeing 7 psi when the turbo is actually producing 11psi?

Jaden

Normally, the turbo has a port with a vacuum line that feeds the Waste Gate. The WG will have let's say a 7 psi spring, so as soon as it hits 7 psi, it will open and dump exhaust around the turbo and open/close in order to try and keep those 7 psi.

EBC will sit in between turbo vacuum feed and WG, and will be opening/closing all the time, trying to aid faster spooling. Then, when it hits target (say 11 psi) it will start blocking/unblocking the psi signal to the WG allowing it to open/close and use/dump exhaust gases trying to hold those 11 psi as best as it could.


It doesn't really say X Psi at X RPM. It will always try to hit target boost as fast as possible. Although, I believe an EBCS can be tuned to delay boost target until whatever RPM you want.

Essentially yes.

Why would it be opening/closing all the time to aid spooling? A closed wastegate is going to provide the fastest spool, there is no reason to open it before you want to start limiting boost.

If the EBC is opening/closing before the WG, the WG will not see the porper boost signal until you want it to, preventing the WG from opening up much before your target boost.

I don't think he means the WG is opening/closing, but the EBC just doing its normal duty cycle thing

Yes, this is what I meant :thumbup:

[ame="https://www.youtube.com/watch?v=OL11Etw7ZSg"]DIY Electronic Boost Controller Install - YouTube[/ame]

EBCS is controlled using PWM (pulse width modulation). Essentially the valve continuously switches what pressure the wastegate sees, between MAP and atmospheric/pre-turbo intake. Let's say your wastegate spring is set at 7 psi as many 86's are for stock block but you're targeting 10 psi. Once you hit 7 psi and your wastegate starts opening, the EBCS is actively cutting off the wastegate's pressure source from MAP, closing the wastegate for a short amount of time before letting it open back up. This increases the boost. The EBCS keeps pulsing the wastegate to hit desired boost. While there is a target boost map, tuners have to tune wastegate timing by duty cycle. It ranges from 0 to 100% and is the % of time that the boost solenoid opens. I don't think the ECU would respond fast enough without a predefined base duty cycle map to both hit desired boost quickly enough without overboosting horribly.

On an EBC how does raising the boost duty cycle speed up turbo response? I understand how lowering the duty cycle can slow the turbo but, how does it make the response faster, some like Apex'i claim they can make larger GT35+'s spool 2x faster.

???

I think the wastegate can start opening before you reach full boost if I'm not mistaken since it gets sprung by partial boost as well as exhaust back pressure. An ebcs can divert the boost "signal" and delay it from opening and can speed up when you fully spool up. As for claims of how much faster, I don't know about that haha.

That's it pretty much. Wastegates open incrementally as boost increases, and manual boost controllers just act as an adjustable leak in the line it looks at for boost, so they can't completely alleviate that issue. They can increase peak boost and improve turbo response somewhat.

EBC's can stay closed until commanded to do otherwise, so the wastegate remains closed long after it normally would, and this results in better turbo response. The duty cycle/PWM nomenclature refers to how they actually limit pressure seen by the wastegate. They use a needle valve that opens and closes with a given frequency as a method of limiting the pressure in the vac line.

Take for example how computer fans work. Variable rpm fans operate on PWM (pulse width modulation), meaning that as you turn the knob up, more pulses per given unit of time are commanded to the motor, in essence it's like someone flicking a light switch on and off at a faster frequency, depending on the higher PWM or Duty Cycle commanded.

A 0% duty cycle would be off, meaning the ebc is doing nothing and the wastegate behaves as though there were no boost controller. 100% would mean completely closed, and the turbo would continue to make higher and higher boost until something breaks. Changing the duty cycle allows you to tune the percentage of boost the wastegate sees. Duty cycle tuning on EBC's is the most basic way to do it, as it behaves like a manual boost controller that you control electronically.

There are also EBC's that can be tuned for very specific inputs (gear, rpm, octane, throttle position, wetness of passenger seat, etc.) that allow you to make the wastegate behave however you want. An example might be 100% duty cycle until Xpsi, then hold that PSI, or increase peak boost with gear or speed to limit the strain on the transmission.

http://en.wikipedia.org/wiki/Boost_c..._boost_control
http://www.superstreetonline.com/how...st-controller/

Question.. Even if running wastegate spring pressure boost of 7psi for example an EBCS would allow the wastegate to stay fully closed till the 7psi's are attained, building boost faster? This i'm assuming takes careful tuning as there's a delay in the ebcs signal and wastegate opening. To prevent overboosting the wastegate will still need to open slightly before hitting the exact 7 psi or does it just open at exactly 7 psi and control boost efficiently?