Disconect BCS does what?

Just to make sure, if I disconect the BCS vacume lines and hook them together I will have how much boost in each gear? Stupid question but thanks!

are you talking about jumping the two vacuum connectons at the turbo? If you are i have done this and i get somewhere in the 17-18 in all gears. The overboost buzzer has gone off on me twice since i did that.



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Bill Lieder
MODS: Ported big valve head with ss valves, ported upper & lower intakes, Racer Walsh #2 Roller cam, Walboro 255HP pump, Kirban adjustable FPR, 3" Exhaust, Star stage 2 clutch w/ stage 3 pp, K&N cone, Gillis valve, Race engineering adjustable cam sproket, 245 50 16 Bridgestone tires

No, not on the turbo. The two vacume lines that go to the boost control solinoid on the inner fender. If I take them off and run them together what will that do? I would think it would then give me full boost in all gears to what ever PSI the factory waste gate is set at. What is it set at anyway? Thanks.

Hey Stangman, that's what bill is talking about. The BCS is the boost control solenoid, it controls where the boost is via electrical connection with the computer. If you attach the vacuum lines together after you take them off of the BCS, then you will get full boost in every gear because you have bypassed the electrical input limitations of the computer. 17-18 lbs of boost like Bill said. It is not wise to set your boost up this way because if the overboost buzzer goes off, then something bad could happen if your turbo is spooling up that high. You don't know if something is wrong with your waste gate or not and that would be the only thing holding back boost. It will take only one try to see if everything is okay with the wastegate and turbo, but if it's not, then it is bye bye turbo. I took the chance, and mine did fine, so I've had it hooked up this way since a month after I got my car. But the correct way is to put a boost controller there and then things will be safe.

You need to understand how boost control really works before you start changing things.

If you have NO signal line to the wastegate actuator, you will boost to the moon. The wastegate is held closed by a spring inside the actuator.

If you run a line from the turbo outlet, to the wastegate actuator, you will get 9-10 lbs of boost.

The factory BCS opens to bleed some signal away from the connection between the turbo outlet, and the wastegate actuator, to let you get more boost. The BCS has an orifice in it that will only bleed to ~15 lbs.

On a stock set-up, connecting the two vacuum lines at the BCS will net around 17 lbs of boost. This is determined by the orifice in the bleed tee on the compressor outlet. If you have an automatic, the orifice is smaller. On some cars, you need to drill the orifice to get more than 15 lbs. This is very tricky to do as it is a very slight change in diameter.

There are other details to this, but this is cut down to its simplest form.

You can do low buck boost control by putting a blue electrical butt splice in between the two lines you disconnected at the BCS, and crimp it to the desired boost setting.

All that the Hallman or Gillis type valves do is block the signal from the turbo outlet to the actuator until the spring is overcome, then the signal is bled by a downstrem orifice, just like you are doing with a butt splice. The BIG difference is that the ball type bleders have better response, as they are not bleeding while boost is building.

Take your intercooler off, and study the hose routing and I believe you will see what is going on.

Hope this helps,
Bob Myers

Wow, BIG difference. I recommend this to anyone brave or stupid enough to risk blowing their turbo. These things are fast!

I haven't tinkered enough weith my car to know exactly which pieces I'm changing... but I am interested... and I would like to try this. Do you have, or can you get, some before and after pictures? I know exactly where everything is at, I just want to verify you know.

Sorry, I have no way of posting pics but I can explain it to you in more detail. Open your hood and look the the left side fenderwell. Just behind the air cleaner you will find a small round object with two vacume lines and an electricle connector going into it. Simply remove both vacume lines and hook them together somehow. I used an inch long piece of metal fuel line but any pipe of the correct size will do. That's it. Watch your boost gauge after to make sure your not boosting past 18 psi. Good luck.