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Lsa blower question.

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Old 08-12-2017, 12:19 AM   #1
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Default Lsa blower question.

So recently something has been on my mind and I'm wondering what some of you that are knowledgeable or out side of the box thinkers think. One of the problem that plagues almost anyone wanting to do a lsa blower swap on anything is that we can't control the blowers valve to prevent part throttle boost and decel boost. Since the the valve is controlled electronically and only ctsv, zr1 and zl1 computers have this feature available. What is your guys opinion on making a custom flange that mounts to the super charger where the valve goes and then running something like a pro charger red race valve off of vacuum. It should provide similar effects and not be electronically activated. I have a buddy that is more than capable of fabbing something nice up (he works for a machine shop and is an amazing welder). I'd also consider having a small run made for his troubles for other guys who might be interested.
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Old 08-12-2017, 01:37 AM   #2
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Originally Posted by silvea View Post
So recently something has been on my mind and I'm wondering what some of you that are knowledgeable or out side of the box thinkers think. One of the problem that plagues almost anyone wanting to do a lsa blower swap on anything is that we can't control the blowers valve to prevent part throttle boost and decel boost. Since the the valve is controlled electronically and only ctsv, zr1 and zl1 computers have this feature available. What is your guys opinion on making a custom flange that mounts to the super charger where the valve goes and then running something like a pro charger red race valve off of vacuum. It should provide similar effects and not be electronically activated. I have a buddy that is more than capable of fabbing something nice up (he works for a machine shop and is an amazing welder). I'd also consider having a small run made for his troubles for other guys who might be interested.
I don't have any electronics to control boost and it works just fine. Soon as I lift the boost gauge goes from 9.5lbs of boost to vacuum and I don't make boost at cruise speed either. I had my Holley controlling it but reconfigured it when I was having an issue with something else and never bothered to redo it.
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Old 08-12-2017, 08:17 AM   #3
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Huh so I mean you may be seeing vacuum as far as MAP and have the car running right, but if that thing is spinning and the engine isn't using it all where is it going? I've heard you can run it without the solenoid but it lessens the life span of the blower. I'm just curious if my original idea could be seen as a solution to a longevity issue.
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Old 08-12-2017, 11:41 AM   #4
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Huh so I mean you may be seeing vacuum as far as MAP and have the car running right, but if that thing is spinning and the engine isn't using it all where is it going? I've heard you can run it without the solenoid but it lessens the life span of the blower. I'm just curious if my original idea could be seen as a solution to a longevity issue.
It's bypassing like it's supposed to. Vacuum holds the bypass open at idle and when you step on it vacuum drops so the bypass closes and you build boost. At part throttle you again have high vacuum and again it opens the bypass.

PS if you're seeing vacuum on the gauge at idle/cruise then you are not making boost obviously and that also means you are not shortening the life of the supercharger.

Last edited by LLLosingit; 08-12-2017 at 11:47 AM.
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Old 08-12-2017, 12:16 PM   #5
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Ah ok. I'm looking to do the swap so I find it interesting. I was afraid it would create a situation like in a turbo car when the throttle body shuts and creates surge hence why they use blow off valves. I guess the difference is that on a turbo it's pushing air through the throttle blade instead of pulling it through. Once that blade shuts the blower can't pull through it. The rotors spin as normal and just less air is allowed to be moved? Would the rotor trying to push more air then allowed add stess? Since they spin at high speeds if Roma are up like in a decel situation.
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Old 08-12-2017, 12:46 PM   #6
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The bypass actuator is connected to an internal door inside the case of the supercharger. When the door is opened the air recirculates inside the case/snout in a loop, when it's closed the air has nowhere to go but into the combustion chambers.
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Old 08-12-2017, 12:47 PM   #7
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But stock it's electronically activated correct? So how do you get it to operate manually
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Old 08-12-2017, 01:22 PM   #8
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Stock from my understanding the computer controls over boost, Other than that it's still vacuum that opens and closes the bypass so you simply run the vacuum line from the vacuum source to the bypass valve. I'd have to look but I'm pretty sure this is how mine is routed. Keep in mind that this is the same way that some in the aftermarket bypass their blowers.
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Old 08-12-2017, 02:19 PM   #9
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I mean it's not possible to overboost a belt driven system it's there to relieve pressure. What situation it's activating that won't function is the question.
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Old 08-12-2017, 03:08 PM   #10
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My guess would be that GM doesn't want full boost in 1st or 2nd gear, I have no idea. You're making this much more complicated than it needs to be. The actuator gets it's vacuum between the throttle body and the rotors (suction side), When you open the throttle blade that area looses vacuum in turn closing said actuator (Boost). At part/light throttle there is still vacuum in that area so the actuator arm pulls open the bypass (No Boost). It's really that simple.
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Old 08-12-2017, 03:12 PM   #11
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Here is what I found take it for what it's worth it's on the internet after all.

The ECM disables boost under the following conditions:

• Reverse gear is selected.

• Drivetrain abuse is detected.

• Electronic throttle control (ETC) fault is detected.

• Engine coolant temperature (ECT) is greater than 125C (257F).

• An intercooler pump failure is detected.

• Intake air temperature (IAT) sensor 2 is equal to or greater than 120.5C (248F), boost pressure is limited to 145 kPa (7 psi). The ECM commands the boost control solenoid to default to 62 percent DC.

• Vehicle speeds exceed 159 mph in third, second, and fourth gears only, after 150 seconds boost is trimmed actively.

OVERBOOST The following conditions will result in full boost to be commanded at all times. These conditions can also result in overboost conditions during high engine load situations.
• A boost control solenoid control circuit shorted to ground.

• A boost control solenoid valve is stuck closed.

• A restriction in the boost source or signal vacuum hoses.

• A restriction in the exhaust system may cause an overboost condition and reduced fuel economy.

A restriction in the vacuum signal hose to the bypass valve actuator or stuck closed bypass valve will cause a noisy idle and reduced fuel economy.

More details found here
http://www.cadillacforums.com/forums.../t-203271.html

Last edited by LLLosingit; 08-12-2017 at 03:18 PM.
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Old 08-13-2017, 11:33 AM   #12
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Ah got it. That's solid information thank you. I understand more now.
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