supercharger

i asked earlier about my supercharger not giving me full boost. the vacuum lines semm to be on the right locations and i have also checked for leaks. i put a new bypass valve acuator on and adjusted it porperly but that didnt seem to help. i was wondering how i can tell if the bypass valve is adjusted properly or if anyone has an idea on whats wrong. thanks for the help!

Here's the adjustment procedure less pics. Did you have any boost problems before the supercharger rebuild?

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
(Picture: Tools Needed)


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!

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

Here's the adjustment procedure less pics. Did you have any boost problems before the supercharger rebuild?

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
(Picture: Tools Needed)


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!

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

no i didnt have any problems before the rebuild. is the SC hooked into the computer some how? i have been told no and yes. the car before when i would go up a hill it would give me boost before it downshifted and now it will just downshift. does the computer tell it when the car needs more power or is that all vacuum operated? thanks for all your help

no i didnt have any problems before the rebuild. is the SC hooked into the computer some how? i have been told no and yes. the car before when i would go up a hill it would give me boost before it downshifted and now it will just downshift. does the computer tell it when the car needs more power or is that all vacuum operated? thanks for all your help

I don't remember if I asked you earlier but what size pulley are you running.

I don't remember if I asked you earlier but what size pulley are you running.

factory, i believe its a 4 inch. i had a undersize on the last one that was a 3.4 inch.

factory, i believe its a 4 inch. i had a undersize on the last one that was a 3.4 inch.

Just wanted to double check. The stock is 3.8. Are you experiencing any driveability problems or are you just referring to the reading on your boost gauge with the rebuilt supercharger as to what you remember with the old one.

The answer to your question about what controls the supercharger is it is a combination of things like engine parameters (vacuum, MAP, rpms, throttle position, MAF, etc.) via the PCM module. The PCM module has the driver circuits to control boost bypass and controls it electrically at the boost bypass solenoid. Of course, actual boost is determined by SC pulley size. When you get it on or get into a load situation the boost bypass valve closes. At idle, cruising, etc. the boost bypass valve is opened to allow the supercharger to freewheel.

Another suggestion would be to make sure the supercharger manifold bolts are torqued properly and check engine vacuum with an automotive vacuum gauge to see if engine vaccum is in specs. Also make sure the throttle body is torqued properly to the supercharger intake port.

I'm assuming all new gaskets were installed when the supercharger was redone.

Just wanted to double check. The stock is 3.8. Are you experiencing any driveability problems or are you just referring to the reading on your boost gauge with the rebuilt supercharger as to what you remember with the old one.

The answer to your question about what controls the supercharger is it is a combination of things like engine parameters (vacuum, MAP, rpms, throttle position, MAF, etc.) via the PCM module. The PCM module has the driver circuits to control boost bypass and controls it electrically at the boost bypass solenoid. Of course, actual boost is determined by SC pulley size. When you get it on or get into a load situation the boost bypass valve closes. At idle, cruising, etc. the boost bypass valve is opened to allow the supercharger to freewheel.

Another suggestion would be to make sure the supercharger manifold bolts are torqued properly and check engine vacuum with an automotive vacuum gauge to see if engine vaccum is in specs. Also make sure the throttle body is torqued properly to the supercharger intake port.

I'm assuming all new gaskets were installed when the supercharger was redone.
it runs and drives just the same. i have noticed that it gets only about 25 mpg at 70 mhp on the highway compared to 29 before. do you know what the torque specs are offhand?

it runs and drives just the same. i have noticed that it gets only about 25 mpg at 70 mhp on the highway compared to 29 before. do you know what the torque specs are offhand?


Throttle body bolt/nut = 89 in-lbs

Supercharger to intake bolts = 17 ft-lbs

Throttle body bolt/nut = 89 in-lbs

Supercharger to intake bolts = 17 ft-lbs
thanks. would the coumputer restrict the boost or can i just rule that thought out?

thanks. would the coumputer restrict the boost or can i just rule that thought out?

It is possible but I doubt the problem is the PCM but you never know. The last thing you have to go by is the rebuild and replacement. You could just be seeing variations between the 3.4 and 3.8 SC pulley. Plus you had more boost when running the 3.4. The stock boost indicator is not exactly the most reliable method of seeing boost especially after switching out pulleys. An Auto Meter type boost gauge is better and more accurate.

Out of curiosity do you know what parts were replaced when the supercharger was rebuilt?

It is possible but I doubt the problem is the PCM but you never know. The last thing you have to go by is the rebuild and replacement. You could just be seeing variations between the 3.4 and 3.8 SC pulley. Plus you had more boost when running the 3.4. The stock boost indicator is not exactly the most reliable method of seeing boost especially after switching out pulleys. An Auto Meter type boost gauge is better and more accurate.

Out of curiosity do you know what parts were replaced when the supercharger was rebuilt?
as far as i know just the internal parts of the supercharger like the bearings, fins, ect. i replaced the bypass acuator because i broke it in the replacement process but thats it.