ok for those of you that will say do not twin charge I dont wanna hear it, I know it's inefficient and don't care. I'm doing this to be original and that's it.

Ok here is a bit of background info to help out, I am a 2.2 supercharged, and plan on running a super 20g with the stock m62, I would like to bypass around the blower after 6psi. Here is where I'm stumped I cannot figure out how to reverse the bypass of the vacuum based valve. Zzp has refused to help so now I have to figure out how to do this. If someone has any ideas I would love to hear them, and maybe a diagram of the internal workings of the valve might be helpful. I know it's vacuumed based but beyond that idk how to limit it to 6psi.

 

ZZP does sell that eaton boost controller that supposedly can limit boost from the sc. Not sure whether that would work for you or not though

 

hey man, just want to give you my advice for myself owning a twincharged cobalt as well as input from other twincharged cobalt owners as well. I went twincharged for the same reason as you.. to have a unique set-up and make decent power (which definitely attracts attention).
To make a long story short I still am bringing my car to the shop all the time to get the tune just right and finding new issues that pop up here and there. I actually need to bring my car back again because it doesn’t seem to be running as it should. Im making about 429whp which isn’t bad. However, I am making this power with 31 psi! I have a completely build, sleeved and forged block, with stage 2 cams, and pretty much every possible upgrade to the car imaginable as seen on the list on the first page in my signature. With the turbo I am running I could be pushing well over 500whp with less boost and less headaches in tuning. If I were to start from the beginning Id definitely go straight turbo. I was talking to another twincharged owner who also was fully built on the ZZP block and there twincharged set-up (my setup is SMG). He also was having on-going problems with his car and eventually ditched the setup and went straight turbo while at the same time making much more power. The unique idea is definitely cool but the headaches are definitely not worth it in my opinion. I shouldn’t even be saying all this since Im trying to sell my car but Id rather be completely honest without bullshitting anyone. I know you said you don’t want to hear any negative advice from anyone so I respect that. Just want to share my experiences with owning a twincharged cobalt. If you do decide to move forward and go twincharged good luck with your setup and hope you enjoy it!

 

I understand the problems that can occur and have my truck to use as a dd, I plan on using a built 2.4 bottom with my stock 2.2 head, I only want 350-400 hp, can u post pics of how u routed the piping through the engine bay, and I can run an air/air but was gonna substitute e85 instead, I can't control the bypass cuz I'm a 2.2 so I need some ideas to bypass at the 3000 rpm range or 6psi.

 

If you are serious about doing this, I'd look at building the head too. Stock valve springs aren't gonna like the double dose of boost

 

Valve springs are already done, if anything I'd be worried about the valves keeping up, and maybe the sleeves but I think they will be ok

 

The easiest way to set up the bypass valve is to give it enough spring pressure so that it needs 6psi to open it. Use a turbo wastegate actuator if you want it to hold up to high boost pressures without the diapraghm leaking or pushing out. You are basically just setting it up the same as a turbo wastegate in this case.

If you use the stock bypass valve, add a regulator to both ports. Set the one on the top to about 3psi which along with the spring will give you the same as about 6-7psi spring pressure. Then regulate the boost going to the bottom port to never go past 12 psi so that the diapraghm holds up.

 

wow thanks matt, wonder why the sales guy at zzp told me he wouldnt help me at all... should have just emailed you. I cant find the email that you sent me about running the 2.4 bottom end, but say i ran the stock k04 with the 2.4 bottom end with the sc bypassed, think i could hit around 350 reliably?

 

He wouldn't want to get involved in your project that has a high probability of having issues. It happens a lot. It starts out innocently enough where the customer just has a couple questions. Then when it comes down to it, there are a few more questions, then a couple dozen more, then issues arrise and he wants to know what to do about it, etc... You can't really blame him for declining to give out advice to someone that is doing something different than what we sell.

It depends on which LE5 bottom end. The later ones will not be reliable on a 350whp twincharge setup with stock components.

 

I was informed that an 05 or an 06 le5 bottom end that will handle up to 400 tops, and valve springs were all else that was required so long as i keep it under 400 hp

 

With adequate intercooling, that should not be a problem, but you need to figure out the compression ratio before moving in that direction. Running a different head for that particular bottom end could raise the compression ratio much higher than where you want it to be.

 

how much higher... i have a 06 2.2 l61... i really was not wanting to run 10.5-1 compounding boost which is why i wanted to bypass, but if its 11-1 i doubt i could run even a turbo on that

 

Do you see how the questions just start piling up? If the ZZP sales guy gives you an answer that you like, then you proceed to keep asking questions until your project is complete. Sorry to sound like a dick, but just pointing it out since you made it so easy to.

I don't know the chamber size on your 2.2, so I couldn't calculate the compression without looking that up.

 

lol yea they always do, guess i got some more research to do, my bet is it will go up higher because they have the same bore, and the 94.6 stroke to the 98 stroke only makes up .07 liters... and the compression increase only adds another .1 liter which leaves .03 liters left for the head to pick up which means my head area is prolly smaller... smaller means higher compression...

 

Your math is flawed becaused the combustion chamber volume can not affect the displacement of the motor. You just need to know the combustion chamber volumes to figure out the difference in compression ratio.

 

ok i was able to find out on jbody that the chamber size is 53cc, on the 2.2 and 2.0, but could not find any info on the 2.4. would you happen to have that number? They are actually showing that people were running the 2.4 bottoms with lsj heads in 10.5-1 compression for na builds. the bores are all the same in 05-06 so the heads seem to be the same as well. It seems like the pistons are all that was used to change the compression