legacycentral bbs

OK, I'm curious...

I've been thinking about the Turbosmart e-boost for a while. I like it a LOT because it holds the wastegate shut until full boost is acheived.

I was thinking about how this could be done without spending $400 for the E-boost.

What about a check-valve in place of the MBC?

Say you want 15psi of boost. The check valve would be shut until you hit 15psi, then it would open and the wastegate would open up. Keeping the wastegate shut while spooling would help spool times immensely (all exhaust would be going through the turbine).

Would it work? Why wouldn't it be a good idea?

BAC5.2 wrote: like it a LOT because it holds the wastegate shut until full boost is acheived.

This is a goal of almost all aftermarket boost control.

Where did you read/hear that the e-Boost in particular does this?

My interpretation of the Autospeed article on the e-Boost is that its primary advantage over other EBCs is just that it has a more in-depth calibration procedure.

I could be wrong, though, since I know next to nothing about electronic boost controllers specifically.

Say you want 15psi of boost. The check valve would be shut until you hit 15psi, then it would open and the wastegate would open up. Keeping the wastegate shut while spooling would help spool times immensely (all exhaust would be going through the turbine).

What you're describing is usually called a relief valve (a check valve typically opens at a very low pressure, acting as a one-way valve).

The ball-and-spring boost controller you already have in your car is a relief valve, with that desired behavior.

Let me try to draw out how it's constructed:

The inlet to the valve is on the left, and the outlet on the bottom. The O is the ball, and the /\/\/\/\/ is the spring. The #### is the tensioning bolt.

As you can see, until boost pressure overcomes the tension in the spring, it is unable to push the ball past its seat and reach the wastegate actuator.

The : is the bleed orifice in the outlet nipple. This is needed because the valve does kind of act as a check valve -- its one-way action would trap boost pressure in the wastegate actuator and hold it open. The orifice is large enough to let this pressure escape but small enough not to materially interfere with the normal action of the valve.

I was told that about the E-Boost by the Turbosmart Rep at SEMA (and I've met him before, as he's a semi-local).

The quote from their site:

"Programmable gate pressure function to totally eliminate wastegate creep - you tell the wastegate when to open"

The gate pressure function, based on what I've read, is just one parameter of the multi-parameter calibration. I would be amazed to find any EBC that didn't incorporate similar functionality. Like I said, though, the strength here may be that it's directly adjustable.