Boost Bypass Mod???

[ILMODC]

Hey -- What are you guys doing exactly?

I just got a better looked and did some tampering! LOL...

Its not exactly as per that write up ya know. That write up is for the GTP. Which I've done. BUT noticed today that there is this lil hex head screw that pushes this lil piviting tab that pushes that silver bar up in that poppett (the bypass). The hex screw is like an adjustment screw....

Ya see, on the GTPs, you loosen up the three bolts, push the poppett thingy down and retighten the bolts. In theory, making the distance that lil silver bar has to travel.

On my ION today, I just screwed that lil hex screw "in", in which pushes that lil tab in, which reduces that travel that silver bar has to travel. The hex screw I'm talking about is kinda like what a crew on a throttle body would look like. The screw that adjust the idle. The screw, when screwed or unscrewed keeps the throttle body from completly closing.

(geez, did any of that make sense?)

I should have taken some pics to show what I am talking about.

Did the mod today. Screwed that adjustment screw all the way down.

Notice a decent diff. Really what I noticed was that you dont have to push the gas pedal down as far to get boost (that was the point...). Not to bad. Boost seems to be there sooner in the RPM range.

[xtremesc2]

sounds interesting, ill hafta try that one as well.....

[JPK]

Originally Posted by ILMODC

Hey -- What are you guys doing exactly?

I just got a better looked and did some tampering! LOL...

Its not exactly as per that write up ya know. That write up is for the GTP. Which I've done. BUT noticed today that there is this lil hex head screw that pushes this lil piviting tab that pushes that silver bar up in that poppett (the bypass). The hex screw is like an adjustment screw....

Ya see, on the GTPs, you loosen up the three bolts, push the poppett thingy down and retighten the bolts. In theory, making the distance that lil silver bar has to travel.

On my ION today, I just screwed that lil hex screw "in", in which pushes that lil tab in, which reduces that travel that silver bar has to travel. The hex screw I'm talking about is kinda like what a crew on a throttle body would look like. The screw that adjust the idle. The screw, when screwed or unscrewed keeps the throttle body from completly closing.

(geez, did any of that make sense?)

I should have taken some pics to show what I am talking about.

Did the mod today. Screwed that adjustment screw all the way down.

Notice a decent diff. Really what I noticed was that you dont have to push the gas pedal down as far to get boost (that was the point...). Not to bad. Boost seems to be there sooner in the RPM range.

I just loosened the two bolts right under the valve and pushed down on it and tightened them back up. The arm underneath the valve moved down when I pushed down on it and then I just tightened the bolts back up. I'll have to have a look at the hex screw your talking about later today.

[Tim Kish]

The bypass actuator design on the Redline is different from the 3800 in that the bypass stop is built into the actuator bracket. With the mod shown for the 3800 you are only adjusting the preset on the bypass actuator spring. In doing this it requires more inlet vacuum to open the bypass and less to close it, in effect you may realize better boost response (barely). By blindly doing this mod to the Redline actuator you will screw up adjustment of the closed position of the bypass throttle blade. This is adjusted by the small set screw on the bracket. One post above described screwing this adjustment all the way in to increase the spring preset onthe actuator. While that does adjust the preset, it also opens the bypass throttle to higher leakage, which will reduce the boost potential. I don't recommend this mod for the Redline unless it is taylored to the factory service instruction for replacement/adjustment of the Redline bypass actuator.

[Vita]

has anyone with a boost gauge done this yet? wondering what you've noticed on the boost gauge after doing this, early boost build, less boost?

[redline24]

I've got a boost gauge and I really didn't notice that much difference when I tried the bypass mod, other than the gas gauge moving towards empty faster. I moved it back to stock.

[89beretta]

Originally Posted by Vita

has anyone with a boost gauge done this yet? wondering what you've noticed on the boost gauge after doing this, early boost build, less boost?

Yes,
Hello, I am a Field Service Engineer (FSE) with Saturn. As I am reading the posts regarding the boost bypass valve, I'd like to let you know what I know about this component.

You'll notice there are 2 vacuum lines running to it. One holds the valve closed, and the other opens it. The vacuum line that opens it is run by an actuator that controlled by the PCM. The PCM sends an electrical signal to the actuator, which opens to allow vacuum to open the bypass valve.

So, by hooking up a simple vacuum gauge to the actuator, and driving the car, you can see when the computer commands the valve to open. In my experience, the only time that the PCM commands the valve open is in between shifts (most likely for the reasons SCDyne described.) So by disconnecting the PCM controlled side of the valve, you are setting yourself up to have less than smooth air delivery during shifts, for no gain in boost.

If you disconnect the valve on the other side, it will default to always bypass, which will result in a drop in boost.

It's not like a waste gate, it doesn't act as a limiter of boost. In a supercharger, the creation of boost depends solely on the RPM of the supercharger, so your only boost gains come from spinning the supercharger faster at a lower engine speed, which mechanically isn't possible with stock parts. As far as I know there isn't a smaller pully you can buy.

Keep in mind that the output of the super is already at 11psi at high RPM, so the unit may be at it's top potential already. At lower RPM's it's more around 7psi, and builds as RPM's increase.

So bypassing the bypass doesn't "buy" you any horsepower. Believe me, we wouldn't have spent the money on that component if it didn't need to be there.

Good luck guys.

[Vita]

i was merely wondering if boost was allowed to build earlier as was the point of this mod, still no straight answer