That should just lock the bypass into always closed... you were looking at the bypass valve (back drivers side of the S/C) correct?

It appears I don't know what I'm talking about, so I'll shut up now

Coldie

 

Hadden,

Is this the boost by pass valve? I can feel and see a rod (for lack of a better discription) on the underside of it that moves out and in with the movement of the throttle.



Tim

 

Yup, that's it and yours is working correctly!

It's official, I'm a dumba$$

Coldie

 

I thought I was the dumbass, that's why I checked it in the first place, just to be sure.

At least we know somebody's got it right. Now, watch somebody jump up here with "you've got it wrong". LOL

Tim

 

Anyone care to explain why JDM & LFP tell you to hook the boost bypass kit up like the pic below illustrates?





BTW Coldie, being a smartass only cheapens your input.

 

I was quite serious when I said that it appears I was wrong, and so that proves I don't know what I'm talking about.

I'm willing to bet Chikenears understood that...

Coldie

 

I think I understand how the bypass kits and others work.
The pink line that goes to the bypass chamber, when stock gets it's vacuum source through the solenoid which goes to the vacuum reservoir with the check valve that's near the battery.

This way when you're under "over" boost, or powerbraking the truck the PCM can send "stored" vacuum to the chamber to open the bypass. Remember ther is NO manifold vacuum available to open the bypass either under boost or under long periods of neither vacuum or boost. The reason it's slow to recover after the PCM opens the bypass is the solenoid they use is an old smog pump solenoid that was used a long time ago and they were notoriously slow in bleeding off vacuum when they dumped off.

When you remove the pink line from the electric solenoid, and hook it to any good manifold vacuum source, you'll have it operate as you are seeing it. It will be essentially "forced" closed by boost when you are on the throttle hard and as soon as the vacuum returns to the line the bypass will open.

I don't know how long the bypass chamber can take boost before the diaphragm will break. Maybe putting a check valve to prevent boost from reaching it, but allowing vacuum would be a good idea?


Did any of this make sense?

 

Hadden,

You're dead right! I never thought you were being a smartass, just looking for answers like me.

Now, I'm confused again, told ya it would happen. LOL

Tim

 

I'd like to know what the side effects are to doing this mod.. will it cause problems in the longrun? Do you have to be more careful when you punch it?

 

Hamma,

This is the way I understand it;

The boost dump reduces torque being transferred to the transmission during WOT shifts to protect the transmission from the massive amount of torque being slammed into it. It temporarily dumps boost during the shift and slowly makes boost back during the WOT run until another shift occurs and then repeats the process for each successive shift.

It will cause harm to the transmission to disconnect it or bypass it but makes for an more exciting and faster WOT run. I feel sure that the harder you run your truck, the more damage it will do to the tranny.

This is how I understand it, if anybody else knows better please correct me.

Tim

 

Chikenears

I have never seen a post, by someone that should know, stating that boost is reduced at the one-two shift. What I did notice is the truck was not making a "ricer boost blowoff noise" for lack of a better description of the sound, after I did the boost bypass trick. I do run torque reduction.


RedThunder

Great effort in clearing this up.


The why I run the tubing is a little easier to photograph and describe than the JDM routing bu gets the same thing accomplished. Bottom line is...What ever pressure is in the manifold, boost or vacume is fed to the top of the boost dump valve. Under vacume, the valve bypasses air around the blower and under any boost, the port is closed. The computer does not have the ability to over-ride the signal.

Hope this clears things up

Andy

 

So does anyone know if boost is actually dumped during shifts?

 

I am curious also,

Is boost dumped during shifts?

Why do I ask?

I did the boost dump vacuum line re-route described above and I was breaking the rear tires loose at the 1-2 shift on the 1/8 mile track last Friday.

Thinking of taking the boost dump out to lighten up the 1-2 shift. Will this work?

Mark