Can Someone Explain Boost Control Through the Computer to Me?

[short_dustin]

Ok, I've got a '87 GN that I just purchased and TurboBuRick is working to get some things lined out for me. I just ordered a power logger and SD2 chip for the car. I was reading about the chip and people are talking about controlling their boost through the chip.

My question is, I have an external wastegate and manual boost controller on my car currently. What do I need to be able to control boost with the chip and do I need to be able to do it? Also, I've had turbo Buicks with the stock style wastegate and actuator and I controlled the boost by tightening or loosening the actuator rod. What am I missing???? What exactly is needed to control boost with the chip as opposed to popping the hood?

I know this is probably a simple question and I appreciate the help guys!

 

[Raeban]

The goal of any of the boost controllers is to control the boost signal to the wastegate. This pressure signal works in conjunction with a spring in the wastegate or wastegate actuator to control how much force is required for the exhaust to bypass the turbine. The manual controllers as well as the factory solenoid essentially just bleed off some of the boost signal to allow the boost to rise and some of the more slick controllers prevent any signal from going to the wastegate during spooling to allow faster spool-up. When you were adjusting the wastegate actuator rod on the other turbo buicks you were essentially increasing or decreasing the force required to bypass the turbine by compressing or decompressing a spring in the actuator. While each setup gives different results in regards to how quickly the boost ramps up, how accurately it controls, and how much boost can be made, if you have a working external gate and a manual controller I wouldn't fool around trying to make a different system work.

 

[Nick Micale]

..... The manual controllers as well as the factory solenoid essentially just bleed off some of the boost signal to allow the boost to rise and some of the more slick controllers prevent any signal from going to the wastegate during spooling to allow faster spool-up. When you were adjusting the wastegate actuator rod on the other turbo buicks you were essentially increasing or decreasing the force required to bypass the turbine by compressing or decompressing a spring in the actuator............

That is good information, but one thing must be considered with the stock GN is that the factory wastegate was NOT adjustable. The WG solenoid and ECM compensated for this by allowing a little more boost at WOT.

Since the solenoids were problematic from the beginning, it is best to eliminate it when an adjustable WG is used as you can then control the boost more accurately.

Most all aftermarket chips do not include the solenoid function by the ECM.

 

[Raeban]

Nick mentioned a very good point about the limits of the factory solenoid. Even with a chip that has wastegate DC% setup to target a boost level, if so much boost is coming at the solenoid the solenoid becomes overwhelmed and it struggles to provide good control. That is why the factory "Y" has the restrictor on the inlet bell side as to create a pressure drop (and thus less flow) to help the factory solenoid control. I believe there are some guys out there that have hooked two factory solenoids in parallel for more control options but at the end of the day it is about the forces at the wastegate. The manual controllers, especially the RJC work very well. So do some of the after market solenoids that prevent flow to the wastegate rather than bleed off flow. And of course the high end stuff that really allows you set pressures at the gate that don't require boost as the motive force are super slick. All that said, if your system is working stick with it IMO.

 

[Mike Licht]

Most all aftermarket chips do not include the solenoid function by the ECM.

All the Extender, Commander, and Pro chips control the factory solenoid. All the TurboTweak Chips do as well. Which ones were you referring too?

 

[Nick Micale]

Most of the chips that were popular years ago like Red's, ATR, Kenne Bell, Thrasher, Hypertech, Zimmer, Max Effort and a few others from the 1980's/1990's, and Eric does most with no W/G solenoid control.

I guess you and Bob Bailey used that function in your stuff for some reason, but we were able to run fast and win races w/o that variable?

 

[Mike Licht]

every single one of the chips you listed has solenoid control in them including the latest turbotweak. Does not mean you have to use it. In fact the pro chip and SD2 chips have ADJUSTABLE boost from the chip and I have been working with both of them to add it to more chip with a better solenoid like the MAC unit which works really well. In this case it works very much like the XFI does. We all know there is many ways to go fast I was not trying to imply that one way is better than another but if a guy has a chip and reads this he may think his solenoid will no longer work which is simply not the case.

 

[Nick Micale]

After checking with a long-time GN chip expert on this subject, I was told that the WG function was in most chips, but the fault light function was disabled so no code would be set.

However, boost control with the very un-reliable stock solenoid and lack of computer speed/reaction time, does not give quick and accurate response especially with larger turbos.

This may be ok for street cars, but in any type racing there are many better methods and units for boost control.

A closed loop system will provide accurate, variable boost settings which is needed for competition conditions which is usually provided by using CO2.