For those of you on the edges of your seats about the functionality of the cheap ebay boost controller, you can relax. It didn’t work. It would initially over boost before settling back down.  I took apart the tee, and found this (photo on left). I thought the tee contained just a check valve, but the spring was strong enough that it acts as a relief valve. It would boost up to about 18 psi, crack open the ball, and then settle back down. I dropped the spring seconds after taking this picture, and it bounced off the shop floor and into oblivion. I don’t think that is necessarily a bad thing. I will explain.

The following three sketches show:

• The stock configuration
• What I thought I was buying
• What I actually bought

The first uses an electric solenoid to control boost (which the Grand National tries to do blindly). The second uses a “Grainger Type” boost valve that is so named because one can modify parts from Grainger to make it.  I didn’t initially go this route because adjustment results in burned knuckles.  It consists of a simple adjustable home made relief valve. The third sketch shows the Cheap Ebay Manual Boost Controller (CEMBC) that I purchased. As shown in my last post, the CEMBC came with a tee and a variable orifice. Internal to the tee is a fixed orifice and relief valve. The problem was that the boost required to overcome the relief valve was greater than the boost I want to dial in. It was overboosting before the relief valve even opened.

Now for the next test. I’ve completely removed the ball and spring in what I call the Modified Cheap Ebay Manual Boost Controller (MCEMBC). I think that this will provide more accurate feedback to the waste gate actuator, and I do not think they are necessary if no vacuum actuated circuits are connected to that loop. I initially thought that this would cause inconsistencies between immediate Wide Open Throttle and rolling into the throttle more slowly. I’ve thought about it more, and now I think that its operation will be similar to a pneumatic version of a voltage divider. The signal to the waste gate actuator should be a nice, smooth percentage of the boost pressure.The only disadvantage I see to this setup is increased spool up time because it won’t lock the waste gate closed until it reaches the desired boost. Instead, it will open gradually. I think my final solution will be a combination of a “Grainger Type” controller and the MCEMBC. It will really depend on the adjust-ability of the fuel map when I get a chip I can tune.

This post really isn’t for the general populace. I just want to log what I am doing so that I can bounce it off of other car guys to see if they agree. I promise to make the next post about cats, chickens, interior decorating, or something along those lines.