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669 Posts
It seems like people here have been getting (or atleast posting) mixed results in regards to this "vacuum line mod". My results were zero gains, ireguardless of what configuration I used to route the vacuum lines to the by-pass valve actuator. This includes removing the solonoid from the equasion all together. Now others have stated they have had positive results gaining 2+ pounds of boost with this mod. This lead me to thinking:
Has there been any changes to the car over the year that no one is aware of? Possibly a change is the diamiter of the pulley? Mabyee the early cars had a larger pulley that allowed more boost and it was altered through the production due to concerns over the simplicity of the solonoid being bypassed and boost being altered?
The supercharger only induces a fixed ammount of air onto the motor based on its speed of rotation in relation to the motor. This ammount of air in relation to engine speed never changes except for altitude and atmospheric pressure affects and normally this is a very minor factor. What I would like to figure out is if there was a variation in production or either the crank pulley or the supercharger pulley. This is the ONLY place where a possible gain could be seen after removing ECM control of the solonoid over the bypass valve. On my car, even after compleetly bypassing the solonoid and using a direct line to the actuator valve I found no changes in boost pressure.
If there have been no changes in production I can't figure out how some show increases and others do not. If there have not been changes and all engines are the same there should be no way anyone would see an increase in boost pressure at all.
For the people here that have tested this mod and have documented either a gain or no-gain. Could you please post your documented information (by documented I mean either tested with a boost gauge, scan tool, on a chassis dyno or all three) along with the production month and year of your vehicle.
Sorry for the long post, just trying to figure out why some are claiming/getting gains and others are not.
Has there been any changes to the car over the year that no one is aware of? Possibly a change is the diamiter of the pulley? Mabyee the early cars had a larger pulley that allowed more boost and it was altered through the production due to concerns over the simplicity of the solonoid being bypassed and boost being altered?
The supercharger only induces a fixed ammount of air onto the motor based on its speed of rotation in relation to the motor. This ammount of air in relation to engine speed never changes except for altitude and atmospheric pressure affects and normally this is a very minor factor. What I would like to figure out is if there was a variation in production or either the crank pulley or the supercharger pulley. This is the ONLY place where a possible gain could be seen after removing ECM control of the solonoid over the bypass valve. On my car, even after compleetly bypassing the solonoid and using a direct line to the actuator valve I found no changes in boost pressure.
If there have been no changes in production I can't figure out how some show increases and others do not. If there have not been changes and all engines are the same there should be no way anyone would see an increase in boost pressure at all.
For the people here that have tested this mod and have documented either a gain or no-gain. Could you please post your documented information (by documented I mean either tested with a boost gauge, scan tool, on a chassis dyno or all three) along with the production month and year of your vehicle.
Sorry for the long post, just trying to figure out why some are claiming/getting gains and others are not.
