01-22-2019, 09:34 AM | #1 |
Drives: 2017 Camaro 2SS Join Date: Dec 2016
Location: Houston
Posts: 469
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Supercharger Bypass Valve Operation
I am having some trouble with my LT1 to LT4 swap build and hoping someone may have some insight. I have been posting under IAT Logs in order to correct the heat issue I was having. I have figured out that the heat is due to the bypass valve not being operational, but now have questions on why my bypass valve is no longer operational.
First, a description of the build: LT4 blower (blower base PCV welded shut), 2.3 upper pulley, Rotofab intake and ported stock TB. Also have headers/xpipe which I don't think would have any effect. I recently purchased new and replaced my supercharger bypass valve as it was not operating correctly to allow for the bypass valve to open at idle and cruising speeds when the system should be under vacuum and not compressing air. Since replacing the valve it is still not operational and under further inspection both PCV lines going from the blower to the bypass valve diaphragm have suction/vacuum on them at idle. If I remove the line going to the electronic solenoid the bypass valve opens, but immediately upon reconnecting the valve closes. From my understanding this valve should be open at idle and cruise allowing the blower to run cooler and allow for better MPGs. I have double and triple checked that the PCV lines are all correctly run and cannot hear any vacuum leaks with the naked ear when the engine is running. Would having the blower base welded shut have any effect on bypass valve operation? This weld was used instead of replacing the valleycover PCV on the front with a plug. I believe the valley cover still has the stock PCV in it and is possibly venting directly into the engine bay. Thanks for your help...again. |
01-22-2019, 01:14 PM | #2 |
Drives: 2023 ZL1 M6 Join Date: Sep 2018
Location: Pace FL
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Your lt1 doesnt have the electronics for bypass and without power the valve is open. Only make about 4 lbs in this situation assuming stock pulley. Just bypass the bypass.
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01-22-2019, 01:24 PM | #3 | ||
Drives: 2017 Camaro 2SS Join Date: Dec 2016
Location: Houston
Posts: 469
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Quote:
I also know this valve should operate properly off of vacuum after watching the ADM Performance dyno video on their LT1 to LT4 conversion. You can see in the video that the bypass is open at idle and closes as they go WOT. It then reopens once off the throttle. A link to that video is below. |
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01-22-2019, 04:21 PM | #4 |
Drives: 2017 Camaro 2SS Join Date: Dec 2016
Location: Houston
Posts: 469
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I should also add that even removing the solenoid and putting the PCV lines direct from the blower to the diaphragm has the same results...so this does not have anything to do with running through the electronic solenoid.
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01-22-2019, 09:33 PM | #5 |
Drives: ZL1/335i Join Date: Apr 2014
Location: Santa Barbara
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So just to clarify: you do or do not have the electric control solenoid from the ZL1? I’m guessing not, as I don’t see how it would be controlled. But your prior posts are a little confusing on this.
Without bringing home my vacuum pump and doing some testing (or knowing exactly where both ports on the blower go) I can’t be totally sure, though I think I know what your problem is: The bypass valve solenoid is sprung closed. So it’s closed when the engine is off or at WOT (no vacuum). At idle and cruise, high manifold vacuum should pull it open. A normal bypass valve is very simple in operation. Now, the dual ports on the LT4 bypass valve are your issue, IMO. They are located on different sides of the diaphragm. This is so it can be controlled via the electric valve. Vacuum applied to both sides (like your car) is going to result in zero vacuum effectively being applied to the diaphragm. Logic says you are only going to want a line connected to the rear fitting on the bypass. The other should be plugged. If you are running an electronically controlled vacuum valve for the bypass, then we need more info on that. |
01-23-2019, 07:43 AM | #6 | |
Drives: 2017 Camaro 2SS Join Date: Dec 2016
Location: Houston
Posts: 469
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Quote:
As for the electronic solenoid...I do have the part on the car, but it is not wired and as such doesn't do anything. If plugging that port on the diaphragm and the blower solves this issue then I will have an electronic solenoid for sale along with the vacuum lines. |
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01-23-2019, 09:01 AM | #7 |
Dyno Show Queen LOL
Drives: 16 SS & 17 ZL1 Both Yellow Join Date: Jan 2014
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Can you just replace the actuator with an aftermarket 1 then adjust rod for throw? Looks like the aftermarket ones are integrated.
My solenoid was a pain to mount when I upgraded to the 2650. Wifes SS 1 vacuum line actuator 1st pic My 2 line 2650 actuator 2nd pic Solenoid from my Zl1 to run the actuator BTW what did you do with the hole on the bottom of the blower? Run a LT4 valley cover or plug? If you plugged it where did you get it I need to plug mine so when I sale it or I need a new seal I had to reuse my seal so just popped it out.. You took care of this correct?
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01-23-2019, 09:15 AM | #8 | |
Drives: ZL1/335i Join Date: Apr 2014
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01-24-2019, 08:02 AM | #9 |
Drives: 2017 Camaro 2SS Join Date: Dec 2016
Location: Houston
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Thanks everyone! Problem solved!
For those with an LT1 to LT4 swap during install you CANNOT install all vacuum lines to the bypass valve diaphragm assembly. As BMW noted above you must install only the rear vacuum line and plug the other line. |
01-24-2019, 08:48 AM | #10 |
Dyno Show Queen LOL
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Glad u got it going did you buy a lt4 valley cover or plug lowers pcv hole?
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01-24-2019, 08:58 AM | #11 |
Drives: 2017 Camaro 2SS Join Date: Dec 2016
Location: Houston
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05-21-2019, 10:09 PM | #12 |
Drives: 2018 Camaro 2SS, Hyper Blue Join Date: Jun 2016
Location: Next Level Tuning - Chicago
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I know this is an old post, but it has wrong information about the vacuumm solenoid for the bypass valve. I have all the stock lines hooked up to mine and have for over 20k miles without an issue. I wired the solenoid to the ecm when I did the install and it works great. Did this when I wired IAT2 in as well.
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01-13-2020, 06:41 PM | #13 | |
Drives: 17' 1SS 1LE GBA-Black Join Date: Mar 2017
Location: TLV
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Quote:
Can you describe how you wired the solenoid for the bypass valve to the ECM? I.E. which wire / pin at the ECM did you tap into (or did you even have to go into the ECMs loom and locate a specific wire)? Same question about the IAT #2... |
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01-14-2020, 06:27 AM | #14 | |
Drives: 2018 2ss 1le Join Date: Jan 2018
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Quote:
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