GrimmSpeed Electronic Boost Control Solenoid....

[AaronNault]

I have talked with the guys at GrimmSpeed and they said that there Boost Solenoid would work for our cars.. I have done a search for many different things and this has not come up in any of my searches, just wondering if anyone has ever used it or what they think? What kind of retune would you be looking at? Just curious plan on buying quite a few parts for my car and this might be one of them.

Cheers Aaron

[Legacy777]

There's really no need to run a different boost control solenoid. Here's why.

There are primarily two different types of boost control setups, a bleed type and blocking type. The first, a bleed type takes a vacuum/boost reference from the compressor side of the turbo and runs it to the wastegate actuator on the turbine side of the turbo. A line is then tee'd into that line and run to a solenoid. This solenoid is then controlled via the ECU or a separate controller to bleed off boost pressure so that the resulting pressure reaching the wastegate actuator gives you the desired boost level. This type of boost control is found on the newer WRX's. It works, but it allows boost pressure to see the wastegate solenoid prematurely and can increase spool up time. This is also the reason you see companies like Grimmspeed making their solenoids to replace the stock setup.

The other type of setup is a blocking solenoid. The vacuum/boost reference from the compressor side of the turbo is run directly into a solenoid. A line coming out of the solenoid is then run to the wastegate acuator. There is sometimes a vent line from the solenoid that is run back into the intake (pre turbo), or is just vented to atmosphere. The idea behind this solenoid is that the ECU or separate controller can completely block off the boost pressure from the compressor side of the turbo so the wastegate does not see any boost pressure until it is necessary to maintain proper boost levels. This can decrease spool time, and increase boost response. This type of setup is what we currently have on our Legacies. So unless your stock solenoid is bad, there's absolutely no reason to replace it with the Grimmspeed solenoid. If you did want to replace it, a GM boost control solenoid is going to be cheaper and just as effective.

The drawback with the block type solenoid is that it requires a little more tweaking with the boost control maps to maintain boost levels. There just needs to be more settings and control to properly ramp up when the wastegate sees the boost so it can open in time, and not produce boost spikes.

Hope that answers some of your questions