i have a 07' ss/sc with the g85 package. i was screwing around and figured id just try the "boost bypass" mod. well i made sure the top vaccum hose was not leaking and i lost 1.5lbs (roughly) of boost, the car car was much slower? infact after i plugged it back in the car was fine again? knowing my ******* self i prob. screwed somethig up in the process, but has anyone seen this?

 

Same EXACT thing happened to me i have an 05 Though.

 

you probably capped off the wrong line... and also don't cap the vacuum port off the bypass valve itself.

 

Guys this "Boost Bypass Mod" does absolutely nothing for performance.

We have had guys dyno before and after with 0 results.

So in other words, don't waste your time.

This whole myth started back when there were very few aftermarket parts for the Cobalt and people needed a fix.

 

Thats exactly what i thought when i tried it when someone first said to try it, then i noticed my boosy dropped from 18 to 15 and then i just said screw it, it doesnt work.

 

isnt this to when u boosted the car with a smaller pully it was to prevent the car to bleed the boost back to the factory 12.5lbs of boost when running a smaller pully and hptuners diddnt have the ability at the time to bleed the boost or turn off the boost when its above the lbs of boost the new pully gives .

if i am wrong please correct me for this is all i remember

 

ok what are you guys disconnecting? the line off the manifold after the supercharger is the one you want to disconnect from the valve and plug with a screw or something.

 

It just messes with the a/f ratios BADLY. I was only seeing like 16 psi with my 2.5 pulley, plugged the line, saw about 17-18, but then I started to get like a couple degrees of knock.

 

the only time it makes a difference is if your torque management controls your boost instead of timing. For example on my 04 RL, in 1st and 2nd the boost was limited to 60% or something. But I know on later models of the RL and I think all Cobalts the TM controls timing to reduce torque. and ofcourse this mod would help if you have a smaller pulley which then I would recommend custom tuning as you will lean out your car.

 

of course if you add more air your going to mess up your "air" fuel ratio.
When you add more air you create more heat inside the combustion champer promoting pre-ingition which can cause knock. Also when you increase the boost, you increase your VE (volumetric efficiency) which then causes the ECM to follow a different path on the spark table, which can cause higher timing = knock

 

i disconnected the upper line(capped off) and left the port on the sensor open, i figured id jus try it since i read about it

 

boost bypass only works for the 2004 redlines and earlier 05 RL's and ss/sc's. All the later models TQ isnt limited by TQ, its limited by timing.