Vacuum for BOV/wastegate/other crap, and 4 port boost solenoids
 

Hello all, (advance apologies for the number of questions)

I'm trying to sort out the vacuum lines on an EFR build. BW specifically says to plumb the CRV (BOV) into the manifold and the BSCV (wastegate solenoid) inlet to the compressor outlet. Both are after the compressor, so what's the difference? Does it have something to do with the throttle body? Moreover, it doesn't really specify where the BSCV bleed outlet goes. Dump to ambient? Filter? Back to air intake?

I intend on retaining the PCV and evaporative emissions system on the car as well. PCV I'm handling by using an air-oil separator so no oil is actually getting back to the intake tract, but I need an outlet sent there anyways. Evap system is going to be the stock FD system minus the solenoid and catch tank if I don't need it. Where is this supposed to be plumbed into? Before the compressor or after it? The FC arrangement has both before, and the FD has at least the evap after (I forget where the PCV goes).

Lastly, am I missing out on these 4 port solenoids? I'm looking at just running the BSCV that's already on the EFR. As far as I'm aware, the main features are similar. They both operate on PWM for precise control and are by default open (closed for the 4 port) to prevent overboost if a failure occurs. Also, the EFR I got came with one of the Turbosmart dual port IWG-75s so I feel like I'm bodging it to work on the BW BSCV without taking advantage of its potential. I did note that the way Turbosmart recommends you plumb a 3 port solenoid to a dual port wastegate (top port to compressor, bottom port through solenoid) means you would need a normally closed solenoid as opposed to the normally open BW BSCV to prevent overboost at failure. Would I be good to go if I simply swap the bleed and main outlets?

Thank you for your time,
Luke

Difference between the manifold and compressor outlet is that when the throttle plates are shut, there will be vacuum in the intake manifold. BOV opens when it sees vacuum in the manifold which means you lifted off the throttle. I don't have much experience as to benefits of 4 port vs 3 port solenoids so I will let someone else answer that for you

Hi Luke,

The BSCV port goes to the intake manifold, on the engine side of the throttle body. This allows it to see vacuum when the throttle is shut (open valve) and boost when the throttle is open (close valve).

Plumb the solenoid to the barb on the compressor cover. I recommend using a MAC 4-port solenoid. They're about $60 on eBay. With a 3-port, you're either pushing from the top and bottom ports of the wastegate, or just the bottom to open it. With a 4-port, you can pressurize EITHER port which allows you to keep the gate shut for longer. This gives you more control than with a 3-port and you can tune a bit earlier spool by forcing the wastegate shut at lower RPMs. I saw noticeable results with your kit when I switched to a 4port solenoid.

Hi Shane,

I think I've got a good handle on what you mean now. I'll try to update some time with a diagram to see if I'm on the right track.

By the way, did you ever figure out that boost creep issue or a good spring to run with the 0.92 A/R housing? The dyno data logs on your build thread suggest so, but I don't recall reading a follow up after Turbosmart sent the wastegate back to you.

Also, thanks to Lavitz for the BOV heads up.

Regards,
Luke

Hey Pzr2, which turbo r u running? Also can u run an EBC with the 4 port Mac soleniod in conjunction with the twin port? I am thiking to change out to the twin port actuator with the 4 port, looking forward for your info on your setup.
Good post.

The consensus I came to and the manufacturer of the manifold (Turblown) was that the large 4" downpipe and free flowing exhaust were the culprit. I did put a 2.5" ID restrictor in between the midpipe and catback. That was able to hold 13-14psi to redline in the lower gears but I blew the gasket out a few days later. I'd recommend sticking to a 3" downpipe and anything but a straight pipe and you should be okay. Internally gated turbos are really nice and convenient but they also have their headaches.

@Rx7aholic, I'm running a BW EFR9180 .92A/R IWG. Not sure about the EBC and 4 port solenoid. I haven't gotten a 4 port in my hands to tell you how to wire them accordingly. Perhaps you could run both sides simultaneously instead of individually so that it looks like a 3 port solenoid to whatever is controlling it (again, not yet sure about how 4 ports work, lol). What boost controller are you using? I'd would guess that any method of control that can output PWM should suffice. Zero hassle if you're already on a standalone.

@Shaniac, I see, I see. I'll be using a 3 inch downpipe and catalytic converters to mufflers so I shouldn't run into that issue. You also had that cutout, correct? Did that have any effect on spool, or just peak power?

The cutout didn't really do a lot for spool, but did pick up about 60whp on the top end. It did make it creep like crazy though. I couldn't keep it under 21psi at redline with a 7psi spring lol.

I am really surprise that not alot of people is using the 4 port mac soleniod and the turbosmart dual port actuator, alot of guys on gtr and Supra world are using it and very happy with the result, one tuner claim it hold precise boost. I hope we get more people share they input and they setup.