Boost Bypass Mod with 2.8 Intense Kit?
01-12-2006, 06:05 PM
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Boost Bypass Mod with 2.8 Intense Kit?
Ive just got my Intense kit today and will be installing it this weekend. The one question I have is that I keep hearing different information about the boost bypass modification. I know that there are other threads out there about this already, but I want to know if it has to be done with the 2.8 inch pulley and what it is worth. I just keeping hearing different information.
Thanks, Dom
Thanks, Dom
01-12-2006, 06:23 PM
#2
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Read this.
https://www.cobaltss.net/forums/show...53&postcount=4
I think this is the best way and I have done it to my car with no problems for months now.
https://www.cobaltss.net/forums/show...53&postcount=4
I think this is the best way and I have done it to my car with no problems for months now.
01-12-2006, 10:02 PM
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By-Pass Valve
A SUPERCHARGER DOES NOT NEED A BY-PASS VALVE OF ANY KIND, PERIOD!!!!
The throttle valve is ahead of the blower and the boost drops with RPM (without a bypass). Unlike a turbo that when spooled up will produce significant boost even when the throttle is closed (behind the turbo), hence a blow-off or pop-off valve to release the pressure is necessary (vented to the atmosphere).
Modern supercharged cars have a BY-PASS valve not to release boost (which does happen secondary to its designed purpose) but for added fuel economy and longevity of the supercharger and the engine. Don't believe? Go to the Eaton web site and read.
If this valve was mechanical and not controlled by the computer, you could permanently close or weld the passage shut. There would be no immediate damage to the blower or the engine, you would simply shorten the life of these componants because they would always be under load (less fuel economy). However you would always have boost (with proper pulley size).
Being that it is controlled by the computer, the link provided by Zinner is the proper way to ensure that the valve is closed and you are getting full boost at WOT, without the computer having a fit. As Zinner has said, he has been running this set-up for months.
Keep in mind that when the valve is open it allows airflow between the intake manifold (under blower) and the planum just behind the throttle butterfly. It is a closed system (not vented to the atmosphere), for you newbees, no whoooosh!
When you are below the "0" on your boost/vacuum gauge, your engine is taking air through this passage more than through the blower (hence no boost). When you go above the "0" because the valve is restricting or closing this passage all together, your engine is taking the air through the blower (boost).
The idea behind this mod and others that disable the valve by removing vacuum lines was because many here were not getting the full 12.5PSI of boost. Many were at 10 PSI. The mod done by Zinner will ensure the valve is closed at WOT and still realize the fuel economy and longevity of the blower and engine.
I'm sure GM is preaching to there techs that this is bad or will cause damage. The tech that states that damage will occur is not correct, though maybe this is what he was taught. To this tech, if you are ASE certified in these areas, think about the above statements. If you still don't get it, please visit a reputable compition engine builder that builds blown engines. I believe then you will understand. Maybe the damage they refer to is the fact that longevity will suffer, they don't want to replace major comonents under warrenty because of the issues listed above.
I am not an expert, however I have built close to 100 blown engines from street to class compition running 140 octane fuel (street) to nitromethane (funnycar). The mechanics of supercharging have not changed. NOTE: all these blowers have a blow off PLATE that releases the pressure in case of a backfire. This helps keep the blower on the engine instead of tossing it 50ft into the air. We also used straps to help contain the blower if the plate failed or was not sufficient.
Sorry so long guys but there are a lot of people here that don't understand this.
If I could find a way to close this valve all the time without a CEL I would, and so would a lot of others.
The throttle valve is ahead of the blower and the boost drops with RPM (without a bypass). Unlike a turbo that when spooled up will produce significant boost even when the throttle is closed (behind the turbo), hence a blow-off or pop-off valve to release the pressure is necessary (vented to the atmosphere).
Modern supercharged cars have a BY-PASS valve not to release boost (which does happen secondary to its designed purpose) but for added fuel economy and longevity of the supercharger and the engine. Don't believe? Go to the Eaton web site and read.
If this valve was mechanical and not controlled by the computer, you could permanently close or weld the passage shut. There would be no immediate damage to the blower or the engine, you would simply shorten the life of these componants because they would always be under load (less fuel economy). However you would always have boost (with proper pulley size).
Being that it is controlled by the computer, the link provided by Zinner is the proper way to ensure that the valve is closed and you are getting full boost at WOT, without the computer having a fit. As Zinner has said, he has been running this set-up for months.
Keep in mind that when the valve is open it allows airflow between the intake manifold (under blower) and the planum just behind the throttle butterfly. It is a closed system (not vented to the atmosphere), for you newbees, no whoooosh!
When you are below the "0" on your boost/vacuum gauge, your engine is taking air through this passage more than through the blower (hence no boost). When you go above the "0" because the valve is restricting or closing this passage all together, your engine is taking the air through the blower (boost).
The idea behind this mod and others that disable the valve by removing vacuum lines was because many here were not getting the full 12.5PSI of boost. Many were at 10 PSI. The mod done by Zinner will ensure the valve is closed at WOT and still realize the fuel economy and longevity of the blower and engine.
I'm sure GM is preaching to there techs that this is bad or will cause damage. The tech that states that damage will occur is not correct, though maybe this is what he was taught. To this tech, if you are ASE certified in these areas, think about the above statements. If you still don't get it, please visit a reputable compition engine builder that builds blown engines. I believe then you will understand. Maybe the damage they refer to is the fact that longevity will suffer, they don't want to replace major comonents under warrenty because of the issues listed above.
I am not an expert, however I have built close to 100 blown engines from street to class compition running 140 octane fuel (street) to nitromethane (funnycar). The mechanics of supercharging have not changed. NOTE: all these blowers have a blow off PLATE that releases the pressure in case of a backfire. This helps keep the blower on the engine instead of tossing it 50ft into the air. We also used straps to help contain the blower if the plate failed or was not sufficient.
Sorry so long guys but there are a lot of people here that don't understand this.
If I could find a way to close this valve all the time without a CEL I would, and so would a lot of others.
01-12-2006, 10:09 PM
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Originally Posted by redrocket
A SUPERCHARGER DOES NOT NEED A BY-PASS VALVE OF ANY KIND, PERIOD!!!!
The throttle valve is ahead of the blower and the boost drops with RPM (without a bypass). Unlike a turbo that when spooled up will produce significant boost even when the throttle is closed (behind the turbo), hence a blow-off or pop-off valve to release the pressure is necessary (vented to the atmosphere).
Modern supercharged cars have a BY-PASS valve not to release boost (which does happen secondary to its designed purpose) but for added fuel economy and longevity of the supercharger and the engine. Don't believe? Go to the Eaton web site and read.
If this valve was mechanical and not controlled by the computer, you could permanently close or weld the passage shut. There would be no immediate damage to the blower or the engine, you would simply shorten the life of these componants because they would always be under load (less fuel economy). However you would always have boost (with proper pulley size).
Being that it is controlled by the computer, the link provided by Zinner is the proper way to ensure that the valve is closed and you are getting full boost at WOT, without the computer having a fit. As Zinner has said, he has been running this set-up for months.
Keep in mind that when the valve is open it allows airflow between the intake manifold (under blower) and the planum just behind the throttle butterfly. It is a closed system (not vented to the atmosphere), for you newbees, no whoooosh!
When you are below the "0" on your boost/vacuum gauge, your engine is taking air through this passage more than through the blower (hence no boost). When you go above the "0" because the valve is restricting or closing this passage all together, your engine is taking the air through the blower (boost).
The idea behind this mod and others that disable the valve by removing vacuum lines was because many here were not getting the full 12.5PSI of boost. Many were at 10 PSI. The mod done by Zinner will ensure the valve is closed at WOT and still realize the fuel economy and longevity of the blower and engine.
I'm sure GM is preaching to there techs that this is bad or will cause damage. The tech that states that damage will occur is not correct, though maybe this is what he was taught. To this tech, if you are ASE certified in these areas, think about the above statements. If you still don't get it, please visit a reputable compition engine builder that builds blown engines. I believe then you will understand. Maybe the damage they refer to is the fact that longevity will suffer, they don't want to replace major comonents under warrenty because of the issues listed above.
I am not an expert, however I have built close to 100 blown engines from street to class compition running 140 octane fuel (street) to nitromethane (funnycar). The mechanics of supercharging have not changed. NOTE: all these blowers have a blow off PLATE that releases the pressure in case of a backfire. This helps keep the blower on the engine instead of tossing it 50ft into the air. We also used straps to help contain the blower if the plate failed or was not sufficient.
Sorry so long guys but there are a lot of people here that don't understand this.
If I could find a way to close this valve all the time without a CEL I would, and so would a lot of others.
The throttle valve is ahead of the blower and the boost drops with RPM (without a bypass). Unlike a turbo that when spooled up will produce significant boost even when the throttle is closed (behind the turbo), hence a blow-off or pop-off valve to release the pressure is necessary (vented to the atmosphere).
Modern supercharged cars have a BY-PASS valve not to release boost (which does happen secondary to its designed purpose) but for added fuel economy and longevity of the supercharger and the engine. Don't believe? Go to the Eaton web site and read.
If this valve was mechanical and not controlled by the computer, you could permanently close or weld the passage shut. There would be no immediate damage to the blower or the engine, you would simply shorten the life of these componants because they would always be under load (less fuel economy). However you would always have boost (with proper pulley size).
Being that it is controlled by the computer, the link provided by Zinner is the proper way to ensure that the valve is closed and you are getting full boost at WOT, without the computer having a fit. As Zinner has said, he has been running this set-up for months.
Keep in mind that when the valve is open it allows airflow between the intake manifold (under blower) and the planum just behind the throttle butterfly. It is a closed system (not vented to the atmosphere), for you newbees, no whoooosh!
When you are below the "0" on your boost/vacuum gauge, your engine is taking air through this passage more than through the blower (hence no boost). When you go above the "0" because the valve is restricting or closing this passage all together, your engine is taking the air through the blower (boost).
The idea behind this mod and others that disable the valve by removing vacuum lines was because many here were not getting the full 12.5PSI of boost. Many were at 10 PSI. The mod done by Zinner will ensure the valve is closed at WOT and still realize the fuel economy and longevity of the blower and engine.
I'm sure GM is preaching to there techs that this is bad or will cause damage. The tech that states that damage will occur is not correct, though maybe this is what he was taught. To this tech, if you are ASE certified in these areas, think about the above statements. If you still don't get it, please visit a reputable compition engine builder that builds blown engines. I believe then you will understand. Maybe the damage they refer to is the fact that longevity will suffer, they don't want to replace major comonents under warrenty because of the issues listed above.
I am not an expert, however I have built close to 100 blown engines from street to class compition running 140 octane fuel (street) to nitromethane (funnycar). The mechanics of supercharging have not changed. NOTE: all these blowers have a blow off PLATE that releases the pressure in case of a backfire. This helps keep the blower on the engine instead of tossing it 50ft into the air. We also used straps to help contain the blower if the plate failed or was not sufficient.
Sorry so long guys but there are a lot of people here that don't understand this.
If I could find a way to close this valve all the time without a CEL I would, and so would a lot of others.
The problem isn't the by-pass valve (butterfly inside the supercharger), but the problem is the selenoid that say to the by-pass valve : Open past 12 PSI ! There has been a LOT and a LOT of thread (some personnaly written by me) that said exactly (and that's VERY simple) how to fix these issues.
01-12-2006, 10:09 PM
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One More Thing
Gforce477,
If you have to remove the blower to install the pulley. It would be a good time to look at this valve and make sure it closes completely. Use a vacuum pump to pull 18in and release it. If the valve opens fully and especially closses fully, you probably don't need this mod as the valve is working properly.
If you have to remove the blower to install the pulley. It would be a good time to look at this valve and make sure it closes completely. Use a vacuum pump to pull 18in and release it. If the valve opens fully and especially closses fully, you probably don't need this mod as the valve is working properly.
01-12-2006, 10:13 PM
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Redrocket the valve is surely working properly. The problem is there is an electrical selenoid (controlled by the PCM) that force the by-pass valve to open past 12 PSI.
01-12-2006, 10:34 PM
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Exactly
Originally Posted by Jmc007
Redrocket the valve is surely working properly. The problem is there is an electrical selenoid (controlled by the PCM) that force the by-pass valve to open past 12 PSI.
This is why when your cruising you dont have boost. My point was that its not necessary mechanicly to have it. Wouldnt you like to have 10psi at say 2K rpm and max 12psi or more at say 3Krpm. However I dont believe the stock pulley will go much higher even with the valve disabled. However, the guys running 2.8's would benefit the most from closing this valve. Also the seleniod is not electric on the valve. The seleniod only opens or closes the vacuum line connected to the valve.
01-13-2006, 07:36 AM
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Man with all respect, there is some points in your sentences that are wrong. I have spent so much time and energy writing posts on that subject (just so some search) that I doesn't want to say more about it.
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