While doing research through the forums about the boost bypass actuator I discovered some things that are important for terminator owners. It has been debated over and over about the boost bypass modification that prevents the boost bypass actuator from bleeding off extra air when not in boost. I actually drove around with the modification done for 4 years thinking the whole time that it was not causing any performance issues.
I recently found out through reading through threads about this, that disabling the boost bypass actuator actually causes the blower to build up to much heat when not in boost. Apparently when not in boost the Eaton blower, especially with a pulley, moves more air than the engine can take at low throttle rpm. The result is air turbulence called cavitation which causes friction and heat. The improper method for doing the boost bypass was very popular when these cars first came out. If you bought your car used there is a chance that someone did the mod and you don't know it. To find out you can review the RPM outlet method of doing this mod HERE
So a while back I switched the two vacume lines back so that the actuator was functional again. The result was that the air intake temps dropped about 20 degrees when just driving around not in boost. However, the boost bypass solenoid still caused the boost bypass actuator to bleed off boost at wide open throttle. This happens even if the solenoid is disabled in the tune! The car did not pull as good as it did before I reversed the boost bypass mod. I wanted the boost back, but I did not want the high intake temps that go along with disabling the actuator.
I kept on reading old threads and came across a post by RWTD the tuner. He mentioned a rerouting of the vacume lines that he does that prevents boost bleed off at wide open throttle, while at the same time enabling the boost bypass actuator to continue to function while not in boost. That thread can be found HERE.
My original post about this was in the engine tuning section. I did the mod three different ways in that thread. I am only going to show the final method for doing this mod that I showed in the original thread in this How To post. If you wish to see the original thread you can view it HERE
For reference this mod is to eliminate the boost solenoid from being able to open the boost bypass actuator when in boost only. Where as the old "Boost Bypass Mod" Disabled the boost bypass actuator entirely. So this mod I am showing accomplishes what the original mod was supposed to without any of the negative side effects. Here is the area of the engine bay in question here.
For those of you not familiar with how the whole system is supposed to work here is my best explanation. The item labled "Boost Dump Valve" is connected to a little round valve on the bottom of the blower post rotor. When vacuum is applied to the top fitting on this actuator, the metal rod that is attached to the bottom of it pulls up which opens the little bypass valve in the blower. It is critical that this works because if it does not, your blower will heat up your intake charge very quickly even when driving around out of boost.
From the factory the vacuum applied to the top fitting on this "Boost Dump Valve" is regulated by the item labeled "Boost Dump Solenoid". This is not the way you want it hooked up if you are running above stock levels of boost. If you are running any kind of boost above stock you need to change where the boost actuator gets it vacuum from when not in boost.
There are two main areas on the back of the supercharger next to the plenum where vacuum lines are tied into. The top port in the above picture is where the "Boost Dump Solenoid" is connected to. This vacuum port only ever sees vacuum and never boost because it is above the rotors inside the blower.
The bottom port on the back off the supercharger in the below picture has two lines comming off of it. These two lines see both vacuum and boost because they are below the rotors of the supercharger. The red line on the right connects to the Fuel Rail Pressure Sensor. The red line on the left goes to the factory boost gauge. What we want to do is T into the line on the right and connects to the FRPS (fuel rail pressure sensor).
STEP 1:
Take a nice sharp razor blade and slice through all of the tape that is wrapped around the 3/4" conduit that hides all of the vacuum lines, and remove the conduit exposing all of the vacuum lines. No Pics off this.
STEP 2:
Cut the top vacuum line on the top port on the back of the blower and cap it. MAKE SURE THIS IS THE ONE CONNECTED TO THE BOOST SOLENOID ON YOUR CAR. I am not sure if it is all ways the same. You can get vacuum caps like this from any auto parts store.
The line you are cutting and capping should lead to the line labled #1 in this picture.
STEP: 3
Now just to be clear, we are going to remove all of the lines connected to the boost actuator from the car entirely. If you ever think you might want to return it back to stock (no reason to) then don't remove them. Just leave them in place and cap where they where attached to. Here is a pic of where the lines that you are going to remove from the car are attached to.
The thick line that comes off of the lower port on the "Boost Dump Solenoid" couples into a hard line that routes around the back of the blower and ends up dead ending at this canister thing.
Here is what the mess looks like after you have removed it from the car.
STEP 4:
Now you are going to remove the line that goes from the lower port on the "Boost Dump Valve". Then cap where it attached on the intake tube. This line can be left in place. However, it just gets in the way when ever you pull the intake pipe out why not remove it? Also the lower port on the boost dump valve (boost bypass actuator) can be vented to atmosphere now. This does not leave the vacuum system open to atmosphere because the diaphram inside the boost dump valve is air tight.
Before
After
STEP 5:
For this step you will need some vacuum couplers and a vacuum T fitting from the auto parts store, You can also reuse some of the ones you just removed from the car if you want to. I can't remember how many of which kind I bought, it should not be to hard to figure out.
Now we are going to tap into that line that goes from the lower vacuum port on the blower to the FRPS (fuel rail pressure sensor). I think the best way to do this is just to find a spot on this line that is about 1" left of lined up with the top port on the boost dump valve like this.
STEP 6:
Now you are going to steal some of the hard line you removed from the car and some of the fittings you removed from the car and make a new hard line that goes to the top port on the actuator. In order to use the hardline without the nipples molded into the ends of it you are going to have to go and get a zip tie gun from Harbor Freight. They are like 9 bucks. These zip tie guns get the zip ties so tight that there is no way for a leak or the line popping out under boost.
STEP 7
Salvage some more off that vacuum line small ID conduit and put a couple of sections on the lines that go to the EGR solenoid (red and green lines). Also zip tie the hard lines together, NOT USING THE GUN. The gun would make them way to tight, and all you want to do is make them tidy not crush them.
Step 8
Now you are going to install some 1/2" conduit where the 3/4" conduit used to be. Then you will need to steal one small section of 3/4" conduit and place that over where you T'd into the line. I cut a small square out of this peice of conduit dead center at the seem so that it would fit over it nicely without a gap.
Now you are finished, all that is left to do now is go out and feel how your car has picked up throttle response and power up top!
I recently found out through reading through threads about this, that disabling the boost bypass actuator actually causes the blower to build up to much heat when not in boost. Apparently when not in boost the Eaton blower, especially with a pulley, moves more air than the engine can take at low throttle rpm. The result is air turbulence called cavitation which causes friction and heat. The improper method for doing the boost bypass was very popular when these cars first came out. If you bought your car used there is a chance that someone did the mod and you don't know it. To find out you can review the RPM outlet method of doing this mod HERE
So a while back I switched the two vacume lines back so that the actuator was functional again. The result was that the air intake temps dropped about 20 degrees when just driving around not in boost. However, the boost bypass solenoid still caused the boost bypass actuator to bleed off boost at wide open throttle. This happens even if the solenoid is disabled in the tune! The car did not pull as good as it did before I reversed the boost bypass mod. I wanted the boost back, but I did not want the high intake temps that go along with disabling the actuator.
I kept on reading old threads and came across a post by RWTD the tuner. He mentioned a rerouting of the vacume lines that he does that prevents boost bleed off at wide open throttle, while at the same time enabling the boost bypass actuator to continue to function while not in boost. That thread can be found HERE.
My original post about this was in the engine tuning section. I did the mod three different ways in that thread. I am only going to show the final method for doing this mod that I showed in the original thread in this How To post. If you wish to see the original thread you can view it HERE
For reference this mod is to eliminate the boost solenoid from being able to open the boost bypass actuator when in boost only. Where as the old "Boost Bypass Mod" Disabled the boost bypass actuator entirely. So this mod I am showing accomplishes what the original mod was supposed to without any of the negative side effects. Here is the area of the engine bay in question here.
For those of you not familiar with how the whole system is supposed to work here is my best explanation. The item labled "Boost Dump Valve" is connected to a little round valve on the bottom of the blower post rotor. When vacuum is applied to the top fitting on this actuator, the metal rod that is attached to the bottom of it pulls up which opens the little bypass valve in the blower. It is critical that this works because if it does not, your blower will heat up your intake charge very quickly even when driving around out of boost.
From the factory the vacuum applied to the top fitting on this "Boost Dump Valve" is regulated by the item labeled "Boost Dump Solenoid". This is not the way you want it hooked up if you are running above stock levels of boost. If you are running any kind of boost above stock you need to change where the boost actuator gets it vacuum from when not in boost.
There are two main areas on the back of the supercharger next to the plenum where vacuum lines are tied into. The top port in the above picture is where the "Boost Dump Solenoid" is connected to. This vacuum port only ever sees vacuum and never boost because it is above the rotors inside the blower.
The bottom port on the back off the supercharger in the below picture has two lines comming off of it. These two lines see both vacuum and boost because they are below the rotors of the supercharger. The red line on the right connects to the Fuel Rail Pressure Sensor. The red line on the left goes to the factory boost gauge. What we want to do is T into the line on the right and connects to the FRPS (fuel rail pressure sensor).
STEP 1:
Take a nice sharp razor blade and slice through all of the tape that is wrapped around the 3/4" conduit that hides all of the vacuum lines, and remove the conduit exposing all of the vacuum lines. No Pics off this.
STEP 2:
Cut the top vacuum line on the top port on the back of the blower and cap it. MAKE SURE THIS IS THE ONE CONNECTED TO THE BOOST SOLENOID ON YOUR CAR. I am not sure if it is all ways the same. You can get vacuum caps like this from any auto parts store.
The line you are cutting and capping should lead to the line labled #1 in this picture.
STEP: 3
Now just to be clear, we are going to remove all of the lines connected to the boost actuator from the car entirely. If you ever think you might want to return it back to stock (no reason to) then don't remove them. Just leave them in place and cap where they where attached to. Here is a pic of where the lines that you are going to remove from the car are attached to.
The thick line that comes off of the lower port on the "Boost Dump Solenoid" couples into a hard line that routes around the back of the blower and ends up dead ending at this canister thing.
Here is what the mess looks like after you have removed it from the car.
STEP 4:
Now you are going to remove the line that goes from the lower port on the "Boost Dump Valve". Then cap where it attached on the intake tube. This line can be left in place. However, it just gets in the way when ever you pull the intake pipe out why not remove it? Also the lower port on the boost dump valve (boost bypass actuator) can be vented to atmosphere now. This does not leave the vacuum system open to atmosphere because the diaphram inside the boost dump valve is air tight.
Before
After
STEP 5:
For this step you will need some vacuum couplers and a vacuum T fitting from the auto parts store, You can also reuse some of the ones you just removed from the car if you want to. I can't remember how many of which kind I bought, it should not be to hard to figure out.
Now we are going to tap into that line that goes from the lower vacuum port on the blower to the FRPS (fuel rail pressure sensor). I think the best way to do this is just to find a spot on this line that is about 1" left of lined up with the top port on the boost dump valve like this.
STEP 6:
Now you are going to steal some of the hard line you removed from the car and some of the fittings you removed from the car and make a new hard line that goes to the top port on the actuator. In order to use the hardline without the nipples molded into the ends of it you are going to have to go and get a zip tie gun from Harbor Freight. They are like 9 bucks. These zip tie guns get the zip ties so tight that there is no way for a leak or the line popping out under boost.
STEP 7
Salvage some more off that vacuum line small ID conduit and put a couple of sections on the lines that go to the EGR solenoid (red and green lines). Also zip tie the hard lines together, NOT USING THE GUN. The gun would make them way to tight, and all you want to do is make them tidy not crush them.
Step 8
Now you are going to install some 1/2" conduit where the 3/4" conduit used to be. Then you will need to steal one small section of 3/4" conduit and place that over where you T'd into the line. I cut a small square out of this peice of conduit dead center at the seem so that it would fit over it nicely without a gap.
Now you are finished, all that is left to do now is go out and feel how your car has picked up throttle response and power up top!
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