Boost Bypass Valve

[robkiehl21]

Is it a good idea to close the boost bypass valve? Like will it damage anything. Where is it located and how do you close it?

[BNaylor]

No and why do you want to disable/close the boost bypass valve? It is located on the front left side (driver's) of the supercharger. What year is your GTP?

There is some minor adjustment that can be made to change when boost kicks in/out.

[robkiehl21]

It's a '97.. I read on some people's cardomain pages and on here that closing the boost bypass valve will enable the boost to "kick in" sooner.. Like so that you wouldn't have to step into the throttle the whole way for the supercharger to add the boost and so that you get more boost sooner.

[BNaylor]

It varies and you may not get any noticeable results. The boost valve is not being closed all the way. It is simply adjusted towards the closed position...big difference. Plus you do not get any more boost. It only changes when boost occurs. How much boost you get is dependent on the size of your supercharger pulley.

I did the adjustment a few years back and noticed nothing significant. Lets just say my 1/4 mile times did not improve.

Are you stock or modded. If modded what mods?

[robkiehl21]

CAI, Zzp 1.0 pcm, ubend delete, 180 tstat, mainfold/crossover wrap..

[BNaylor]

I'm assuming you are looking for the adjustment procedure, so here it is. Good luck.

Here's the adjustment procedure less pics.

Boost Bypass Valve
(Picture: L67)

Tools Needed:
1 - 3/8 Drive Ratchet
1 - 3/8 Drive Small Extension
1 - 3/8 Drive 10mm Universal Socket


Instructions:
Step 1: Locate hood release in driver side foot well. (Picture 1)

Step 2: Pull hood release toward you to pop the hood open. (Picture 2)

Step 3: Open hood by placing your hand between the hood and front bumper cover, making a left to right motion, catching the hood latch. (Picture 3)

Step 4: Raise hood. (Picture 15)

Step 5: Locate the Supercharger Boost Bypass Valve. It is the black cylindrical object to the left of the supercharger, above the front valve cover. (Picture 4 & then picture 5)

Step 6: Move the large set of wires aside from in front of the valve cover. They are held in place by a metal clip that is easily undone. (Picture 6 & then picture 7)

Step 7: Find the first 10mm nut, located just in front of the Bypass Valve, and loosen nut. DO NOT REMOVE! (Picture 8)

Step 8: Find the other two 10mm nuts; they are located BEHIND the Bypass Valve, on the supercharger housing. (Picture 9)

Step 9: Loosen these two 10mm nuts. DO NOT REMOVE! The first nut can be accessed from the left side of the Bypass Valve, the other one is a little trickier, and can be accessed from the right side. (Picture 10 & then pictures 11, and 12)

Step 10: Once all three nuts are loosened, gently apply pressure in a downward motion to the Bypass Valve. You will notice it may move as much as one-half inch. (Picture 13)

Step 11: While pushing down on the Bypass Valve, retighten the three nuts, in the order you loosened them. First the right side, then the left, and then the front. (Pictures 12, 11, 10, then 8)

Step 12: Re-clip the large set of wires back into the metal clip. (Pictures 7 & then 6)

Step 13: Close hood. (Picture 14 & then 15)

Notes:
Essentially what this free mod does is close the Supercharger’s Boost Bypass Valve sooner than set from the factory. This allows the boost to build quicker, this does not give you more boost. Since the Bypass Valve is not robotically set form the factory, it may be placed higher or lower for some, than others. Some people have noticed significant gains from it, and others have experienced nothing at all. I hope you had fun doing this mod, and hopefully you notice something. I had fun writing this, and taking all the new pictures!

Courtesy of:
Luan Zeqollari
2002 40th Anniversary GTP Coupe
13.72 @ 100.45 (Milan Dragway)

[ericn1300]

Originally Posted by bnaylor

I'm assuming you are looking for the adjustment procedure, so here it is. Good luck.

Step 1: Locate hood release in driver side foot well. (Picture 1)

Step 2: Pull hood release toward you to pop the hood open. (Picture 2)

Step 3: Open hood by placing your hand between the hood and front bumper cover, making a left to right motion, catching the hood latch. (Picture 3)

Step 4: Raise hood. (Picture 15)

LMFAO, so what happened to pics 4 thru 14?

[BNaylor]

Originally Posted by ericn1300

LMFAO, so what happened to pics 4 thru 14?

Hell if I know I'm not the author.

But I guess the author made ZZP's hall of fame so his procedure is now at ZZPerformance. There should be a total of 23 pics.

Click here

[98gpking]

Originally Posted by bnaylor

Hell if I know I'm not the author.

But I guess the author made ZZP's hall of fame so his procedure is now at ZZPerformance. There should be a total of 23 pics.

Click here

Bob i have actualy done some research on the boost bypassa dn have found that actualy closing or lowering the boost bypass valve causing something called flash knock. basicaly at WOT you can develop up to 4.3 knock but only in a flash but it could flash quite quickly making it seem like your picking up 4.3 consistent knock.

i actualy had my car hooked up to a lap top before during and after this process to test it and i for sure got as much as 3.9 flash knock off lowering my boost valve

so my answer to your question above. LEAVE THE BOOST VALVE WHERE IT IS. you will honestly feel no gain if anything youll feel a decrease due to the increase in knock

[BNaylor]

Originally Posted by 98gpking

Bob i have actualy done some research on the boost bypassa dn have found that actualy closing or lowering the boost bypass valve causing something called flash knock. basicaly at WOT you can develop up to 4.3 knock but only in a flash but it could flash quite quickly making it seem like your picking up 4.3 consistent knock.

i actualy had my car hooked up to a lap top before during and after this process to test it and i for sure got as much as 3.9 flash knock off lowering my boost valve

so my answer to your question above. LEAVE THE BOOST VALVE WHERE IT IS. you will honestly feel no gain if anything youll feel a decrease due to the increase in knock

I agree and you have a good point. But you know we have people that believe it will make a difference all because Joe Blow at some other car forum said so, so we give all options including the adjustment procedure.

The boost valve is there for a purpose especially on a street driven GTP. It is set up for a happy compromise between performance and economy. What these guys fail to mention is how their gas mileage went to pot.

In my case it is no big deal because I do not drive my GTP as a daily driver and I use expensive VP Racing C10 unleaded race gas with a custom programmed Intense PCM at the strip so I do not get the flash knock confirmed with Autotap and my KR scan gauge.

But if KR is consistent at other rpms not just at WOT then there will be no gain and most likely a loss not to mention the possible long term damage to the pistons.

This thread at Tips & Maintenance covers what happens when you get KR.

Click here

[98gpking]

Originally Posted by bnaylor

I agree and you have a good point. But you know we have people that believe it will make a difference all because Joe Blow at some other car forum said so, so we give all options including the adjustment procedure.

The boost valve is there for a purpose especially on a street driven GTP. It is set up for a happy compromise between performance and economy. What these guys fail to mention is how their gas mileage went to pot.

In my case it is no big deal because I do not drive my GTP as a daily driver and I use expensive VP Racing C10 unleaded race gas with a custom programmed Intense PCM at the strip so I do not get the flash knock confirmed with Autotap and my KR scan gauge.

But if KR is consistent at other rpms not just at WOT then there will be no gain and most likely a loss not to mention the possible long term damage to the pistons.

This thread at Tips & Maintenance covers what happens when you get KR.

Click here

wow thanks for that link man it helped me more properly understand knock. im actualy scared of it now, not just intimdated

[robkiehl21]

Originally Posted by 98gpking

Bob i have actualy done some research on the boost bypassa dn have found that actualy closing or lowering the boost bypass valve causing something called flash knock. basicaly at WOT you can develop up to 4.3 knock but only in a flash but it could flash quite quickly making it seem like your picking up 4.3 consistent knock.

i actualy had my car hooked up to a lap top before during and after this process to test it and i for sure got as much as 3.9 flash knock off lowering my boost valve

so my answer to your question above. LEAVE THE BOOST VALVE WHERE IT IS. you will honestly feel no gain if anything youll feel a decrease due to the increase in knock

Well, i did do it last week a day, and it seems to engage the boost sooner, but after reading this.. i think im gonna put it back where it was. no point in screwing up the engine for no apparent reason. i was just led to believe that it would make a difference, and it really doesnt, so thanks for that statement.