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I only saw it move a few feet but it was awesome. Time to surprise some ricers!!

So one of the things I still need to work out is the bypass valve on the SC.

I've got it hooked up to the pressure side of the turbo so that it open with boost. Problem is it can only handle about 7psi before it starts to make a funny popping noise. So I'm looking for a way to provide pressure to the line that is the exact same as the turbo, but limit it to ~5psi. I can't find any sort of pressure limit valve, and I'm not sure that a regulator would work fast enough that when the turbo makes 1psi then there is 1psi getting to the bypass valve.

Allowing the flow at low pressure is key to getting a smooth transition. The bypass valve starts to open around 1psi and will hold open around 4. Having a way to adjust it would allow me to tune in the cutoff as well.

Anybody have any ideas? I was thinking I might try to make one using a check ball from a trans, a spring, and some round stock.

I don't see why your idea wouldn't work. Just spec out a spring properly. Otherwise no ideas now, ill chime in if i think of anything.

IIRC the 3800 turbo/sc setups I've seen have some sort of digital boost control. This might be one of the reasons why?

You talking like an aem boost controller?

Also matt are you trying to use the stock bov on the supercharger or a completely different setup.

So close.

Are you gonna self tune it?

Yes, I'm using the stock bypass valve on the SC for the moment. I was trying to keep it simple, but the valve just might not be suited for this use.

Yes I will be self-tuning, with the help of my brother. We are starting off the NIC tune and we have a manual camaro tune too look at as well. Until I can get the fuel system upgraded I'm going to keep the turbo at about 7-9 psi. For the moment I'm limiting it with a 4psi spring so I don't intentionally damage the bypass valve.

So not sure hear but when people pully down amd gat say 15 lbs of boost from just the supercharger does that valve need to be replaced/upgraded? If not i don't see why it wouldn't work.

You should pick up some 60lb injectors so you can run E85 if the opportunity arises. Any corn juice over Michigan?

We have it but it's only in some areas. My friends that run it have to plan ahead anytime they go somewhere kind of far, just in case.

The bypass valve normally uses vacuum to overcome the spring inside, doesn't see boost in the control side. I'm doing the opposite using boost pressure to push it open. It seems to make a difference in the way I've set it up as the other end of the valve is open to the atmosphere.

Do you think it would be possible to use an existing pcm command to control a solenoid, or actuator to bypass the boost. Like maybe the same signal that commands 3rd gear to the trans ran in parallel to a relay.

Just brain storming. Sorry if this sounds ridiculous. And correct me if I am wrong, but I was thinking your intention here is to bypass s/c boost once the turbo is spooled. Which is why you are using positive pressure instead of vacuum on the current bypass. Is this correct, and or there another reason(s) the normal function doesn't work for you?

Wes wrote: your intention here is to bypass s/c boost once the turbo is spooled.

Bingo.

This feels like a dumb question, but I am asking anyway because I am curious. If the boost dumper is dumping air, is it metered by maf? What will the computer do if it's losing metered air?

RJolly87 wrote:This feels like a dumb question, but I am asking anyway because I am curious. If the boost dumper is dumping air, is it metered by maf? What will the computer do if it's losing metered air?

With the s/c boost bypass being inside the M90, everything from the turbo, and outside air will still pass the MAF. It won't change that reading. When the air is bypassed, it goes right into the LIM just before the s/c rotors.

MattStrike wrote:

Wes wrote: your intention here is to bypass s/c boost once the turbo is spooled.

Bingo.

What about the other part. Think it is possible to clone a trans solenoid signal, or maybe a better parameter to kick a relay closed? There are all sorts of 12V solenoids, and actuators out there. Has to be one with the same travel as the boost bypass. If you can weld headers, you could weld a small bracket to hold an actuator.

So, Im sitting here working the mush between the ears and it occurs to me that the stock bypass is already designed to do what you want it to do. If its referencing pressure before the blower vs pressure after the blower, its basically automatically going to switch to the one with higher pressure, correct? If theres more boost coming from the turbo, it should open the valve because that would replicate a low load scenario. When the blower is making more boost, there should be a stronger signal from the LIM and it would close the valve.

This is assuming Im visualizing the system right. My memory is terrible.

My guess is youll run into problems allowing the handoff to happen "naturally" because the areas of efficiency of the two power adders overlap a great deal. Some how or other youll need to "force" the selection based off some parameters, using some means which may or may not involve some sort of elecronic controller. Otherwise I see a huge boost spike from about 2600-5000 rpm.

Right...duhh, the bypass valve already has the solenoid that opens the valve to atmosphere. Forgot about that. So how to go about applying voltage to that solenoid for a different parameter than the factory settings which are just park, and reverse?

You can mess with it in HPTuners.