In Boost Control Systems Explained Part 2, we described the basics behind adding more boost using Manual boost controllers along with how OEM boost control systems work. In this article, we are going to explore using our EBCS Pro solenoid in place of the OEM part. You will see how this can benefit you and your car.
The PERRIN EBCS Pro is a solenoid designed to replace the OEM part to create better boost control. Our solenoid has a few different modes, but is designed to work best in our “Fast Response Mode” or “Interrupt mode”. In this mode, the solenoid requires less duty cycle (DC) to get the desired boost. This means that in situations were the OEM solenoid is working at 100% to do a given job/boost level, it can be setup to use roughly half the DC% and get the same results. In turn this provides more head room for further tuning or adding more boost. We all want more boost!
EBCS Pro Pro in resting position letting air pass through EBCS Pro Pro above is turned on, blocking boost.
A benefit is the EBCS Pro keeps more boost pressure off the wastegate actuator. It does this by blocking pressure going to the wastegate actuator completely when it turns on and off instead of bleeding pressure. This makes the turbo more responsive and spool quicker. Above is a diagram showing how our solenoid is different on the inside compared to the OEM type. It has a few passageways to allow us to set it up more effectively.
Its works like this: Boost enters the solenoid and passes through to the wastegate actuator when the solenoid is turned off. When the solenoid is turned on by the ECU, it blocks boost pressure from getting to wastegate actuator and at the same time relieves any pressure built up in the line going to the actuator. If desired and if programmed to do, so the solenoid can be run to completely block pressure getting to the wastegate actuator until that last moment before a boost spike occurs. This makes for a very fast spooling turbo.
System shown with the solenoid off, and passing the boost right through to the actuator making it open at 10psi.
Now the system is showing the solenoid turned on blocking pressure getting to the actuator and in turn bleeding off any built up pressure that was in the actuator. In turn increasing the overall boost pressure. Now imagine that happening very fast, on and off, varying the degree at which the wastegate is actually open.
This below example shows a stock EVO 9 the OEM solenoid and then retuning the ECU using a PERRIN EBCS Pro. The red line represents the stock boost curve, and the yellow line is the boost curve after ECU tuning and installation of the EBCS Pro. Before we installed the EBCS Pro, the OEM solenoid had issues with holding more than 18psi beyond 6000. After the EBCS Pro was installed, we were able to hold 22psi-20psi past 6000RPM.
This is the same setup but using an external type wastegate. You can see in this setup the hose needs to go to the bottom port. Just like the Internal wastegate setup, at rest it allows the boost to open the wastegate. When on, it blocks the boost going to the wastegate and bleeds off pressure that built up. Again, just like the other diagrams, this all happens very fast, on and off, varying the degree at which the wastegate is actually open.
External Wastegate using Top and Bottom Ports
Another benefit is that the EBCS Pro can be used with aftermarket external wastegates as shown above but with a twist. Because of the configuration of the 3 ports, this enables the use of both top and bottom ports found on most aftermarket external wastegate actuators. In these setups they can provide even better more reliable boost control! While this is not a typical setup, if you are using an external wastegate and can manipulate the tables in the ECU this can make for a powerful setup.
Shown above is the system at rest controlling boost to 10psi, which is the wastegate spring pressure. The top port on the wastegate is vented to atmosphere through the EBCS Pro. The Boost pressure from the turbo is blocked at the EBCS Pro, and flow through to the bottom port pushing the wastegate open.
Shown above is the system energized increasing boost pressure. When the EBCS Pro is turned on, both the top and bottom port on the wastegate see boost pressure. This causes the spring in the wastegate to do all the work. In a properly designed wastegate like a Tial MVR, this allows for a very low pressure spring (like 10psi) to be able to run 30+PSI of boost.
With the solenoid turned off the boost pressure pushes the wastegate open at the set spring rate. The top port is vented to the outside air. When the solenoid turns on, pressure is diverted to the top of the wastegate holding the wastegate closed longer and better. This method is great and allows the use of a very light wastegate spring, but still the ability to run huge boost levels. The reason why using a lower rate spring is this allows for better modulation of boost in part throttle situations where you don’t want too much boost.
Dual EBCS Pros Used For Push Pull Operation
Using dual EBCS solenoids to control boost has a whole other benefit over all the other methods shown. This is the ultimate way to control boost in that you can counteract exhaust pressure. We hit on this in Part 1, where we describe how the wastegate is controlling boost by holding back exhaust pressure and forcing it through the turbine side of the turbo. In some cases where a very high boost pressure, or a very flat boost curve is desired, the exhaust pressure overcomes the wastegate and the spring in it. This is very common to see on small turbos when trying to push them to their limits. In these cases the boost control system and duty cycle of the solenoid are maxed out and still not providing the desired boost. With a properly built wastegate actuator (mainly external types) the two solenoids can be setup to run almost any boost pressure on any turbo regardless of spring installed in wastegate.
Shown above is the dual EBCS Pro system at rest controlling boost to 10psi, which is the wastegate spring pressure. EBCS Pro 1, is blocking boost diverting it through EBCS Pro 2, to the bottom port on the wastegate. The top port on the wastegate is vented to atmosphere through EBCS Pro 1.
Shown above is the Dual EBCS Pro system energized increasing boost beyond 10psi. EBCS Pro 1, is allowing boost to pass through to the top port on the wastegate. This pushes the wastegate closed. EBCS Pro 2 is now blocking pressure getting to the bottom port and relieving pressure from the bottom port on the wastegate. This applies all boost pressure to only the top port keeping the wastegate shut completely.
In this example you can see how this method is very powerful. With a properly designed wastegate with large diameter diaphragm, this can turn a 5psi wastegate spring into one that acts like 30psi! Add to that a very flat boost curve. On this Stage 2 (stock turbo) STI, we are NEVER able to get more than 1BAR / 14.5psi at 6800. With a proper actuator and the Dual EBCS Pro’s we were able to hold 1.25BAR / 18psi at 6800. The best part is, there is even more boost to be gained!
Which Method Do You Choose?
The question that comes to mind is which one is best for me?? That all depends on your intentions, your tuning ability, your mechanical skills, or you budget. After reading all the articles, you should be able to see the benefits of each setup, you just need to weigh those decisions to figure out your best option. But there is one HUGE factor to using the EBCS Pro to its fullest. You need to reprogram the ECU to take into account for each setup. We will take an indepth look at this in our next installment.
Look for Part 4 to go over this along with even more info about your boost control system.