Boost bypass mod on S/C 06 Si

[OneSi]

well, i have read a million different things. some say buy this some say buy that and aparnetly the way to go is the $2.00 way which actually sounds right anyway. the problem is, i dont see many pictures for this and mostly its done on cobras and lightnings because the S/C omen style products(cobalt, ion) etc are just hitting around in our markiet now and are running the same types of set ups. problem is lack of pics for our M62 style S/C. i was browsing around under the hood and there is only one vaccum like i can see to even take off. i think im suppose to "T" it off and run it to the bypass dump but there is no where to even T it to? any help guys? im running a comptech S/C

[OneSi]

Originally Posted by OneSi

well, i have read a million different things. some say buy this some say buy that and aparnetly the way to go is the $2.00 way which actually sounds right anyway. the problem is, i dont see many pictures for this and mostly its done on cobras and lightnings because the S/C omen style products(cobalt, ion) etc are just hitting around in our markiet now and are running the same types of set ups. problem is lack of pics for our M62 style S/C. i was browsing around under the hood and there is only one vaccum like i can see to even take off. i think im suppose to "T" it off and run it to the bypass dump but there is no where to even T it to? any help guys? im running a comptech S/C

ok so i did it. pain in the ass to reach on this si by the way. so i unplugged the hose while it was running and what happened? instant boost at idle.... so definatly not good for fuel economy. now, its suppose to hold boost at higher rpms, i cant exactly tell because the damn car is so fast already. BUT, from low rpms, 1st gear was a little crazy, shift to second i had to let off because the wheels went crazy. so mid range, is picking up GREAT! but as for top holding boost still not sure, i need a guage. i'll try it at the track when i have my good tires if its not freakin rained out. any other info guys???

[XiliX]

Ok, I'm only just learning about boost. I understand functionally what's happening with turbo chargers and superchargers and the different mechanical methods by which they achieve boost. However, I havn't heard of "Boost Bypass" on superchargers.

If you don't mind, could you enlighten me? Is this the ability to bleed off the additional air pressure created by the supercharger so that the car runs near factory specs?

Help a noob out here,

XiliX

[COMplex]

Please post some more info so I can determine if I want to try this or not...

What hose? What does it do? It is boosting more? Or just boosting at lower rpm?

[sheek360]

i used to do that too. Till i was able to control it using stand alone software. Just make sure both sides are plugged. PM me if u need any further info on the supercharger boost bypass.

[OneSi]

Originally Posted by sheek360

i used to do that too. Till i was able to control it using stand alone software. Just make sure both sides are plugged. PM me if u need any further info on the supercharger boost bypass.

yea i guess u can plug both holes.

COMPLEX: under ur S/C is called the "**** i forget the name" lol but it looks like a blow off valve. its a PAIN in the ass to reach and its just one stupid hose that wasnt to piss u off! i have big hands so maybe thats all but if u do it go buy MORE hose and a few vaccum connectors cause its tough to reach. but u just unplug that and plug the hoses and instantly u are boosting..

so yes more when u are idling and as soon as u hit the gas its instant. so first gear will get ALOT of power. i think i may be holding 6psi when i do it all the way through but i cant tell for sure i need a boosy guage.

[KillerNutz]

It would really help if you had someway to monitor the boost i.e. boost gauge. It is hard to "feel" the boost being bled off at the top end, but it is obvious when looking at a gauge. This was a very common mod in the LSJ world, until stand alone software came out that could control this.

[sheek360]

Complex, i hope u dont mind me qouting u

Originally Posted by COMplex

Can you explain a bit more what the bypass does?

On my s/c I have a hose going from the blower to a bypass valve. I think that is the hose that OneSi was talking about.

What exactly are the effects of this? Thanks!

plug it up. u wont discharge boost into the actuator. your engine will ingest all the boost! crazy acceleration. on a ion redline its about 10-15whp gain. The boost gauge will read another LB of boost too. Be careful though, due to the si's compression that extra bit of boost might make u knock.

[COMplex]

Originally Posted by OneSi

yea i guess u can plug both holes.

COMPLEX: under ur S/C is called the "**** i forget the name" lol but it looks like a blow off valve. its a PAIN in the ass to reach and its just one stupid hose that wasnt to piss u off! i have big hands so maybe thats all but if u do it go buy MORE hose and a few vaccum connectors cause its tough to reach. but u just unplug that and plug the hoses and instantly u are boosting..

so yes more when u are idling and as soon as u hit the gas its instant. so first gear will get ALOT of power. i think i may be holding 6psi when i do it all the way through but i cant tell for sure i need a boosy guage.

Ok, the hose going from the blower to the bypass valve. I should add another hose, and plug both ends?

Did comptech tell you about this or are you just doing it on your own? I don't want to void warranties of **** shit up

You said holding 6psi when doing what all the way through?

Where would I connect a boost gauge to find out what's actually being pushed out? I'll try this tonight if its safe... maybe on a dyno

[sheek360]

Originally Posted by COMplex

Ok, the hose going from the blower to the bypass valve. I should add another hose, and plug both ends?

Did comptech tell you about this or are you just doing it on your own? I don't want to void warranties of **** shit up

You said holding 6psi when doing what all the way through?

Where would I connect a boost gauge to find out what's actually being pushed out? I'll try this tonight if its safe... maybe on a dyno

youll definately be voiding your warranty. but they wont know unless u tell em u plugged it. plug the hose, and cover the other end so u wont get dirt in there

[COMplex]

It seems a bit unsafe if you ask me. I don't know how I feel about boosting 6psi ALL the time. Including idle I assume?

I am going to try and get it on a dyno tonight.

[sheek360]

Originally Posted by COMplex

It seems a bit unsafe if you ask me. I don't know how I feel about boosting 6psi ALL the time. Including idle I assume?

I am going to try and get it on a dyno tonight.

U only boost when your WOT. At idle your in HG aka MERCURY aka NEGATIVE BOOST aka BOOST BELOW ATMOSPHERE aka MANIFOLD PRESSURE. I think youll be okay bro

[COMplex]

Originally Posted by sheek360

U only boost when your WOT. At idle your in HG aka MERCURY aka NEGATIVE BOOST aka BOOST BELOW ATMOSPHERE aka MANIFOLD PRESSURE. I think youll be okay bro

LOL ok. I'm not trying to blow up a brand new car... yet.

[sheek360]

with the SI's high redline, i wonder how fast the blower is spinning? Im sure your probably running a large pulley, but it still makes me wonder.

[OneSi]

i believe its a 3in pulley. ok so i went to kragen and grabbed another vaccum line and fitting. im going to get ready for work, head to depot because i can get a valve for a drip fitting for plubing so i can actually open and close it when i want. and actuallty with our cars it seems to be boosting as soon as u touch the gas. see by doing this, u eliminate vaccum. so there is no more the only option is to boost. and 6psi is no biggie. stage 3 will be around 11psi. one thing though, u will be changing ur air fuel ration but 1psi ur ECU should be able to accomodate it and actaully add the fuel. check it out on the dyno bcause im curious. I think u will actually notice the power in the mid and low range the most.

see top end u might only gain 1psi which is ok on our cars thats a decent gain. but mid range, u will not have to build boost at all, it will be right there. last night leaving the drive way after 2500rpm the tires went crazy, hit second and SPINNNN. usually i chirp second and my LSD grabs and goes. that was warmed up to. so check it out man but its easy to change back to stock so dont worry about ur warranty. i should be the one worrying, i have to bring my car there next week.

[sheek360]

Originally Posted by OneSi

i believe its a 3in pulley. ok so i went to kragen and grabbed another vaccum line and fitting. im going to get ready for work, head to depot because i can get a valve for a drip fitting for plubing so i can actually open and close it when i want. and actuallty with our cars it seems to be boosting as soon as u touch the gas. see by doing this, u eliminate vaccum. so there is no more the only option is to boost. and 6psi is no biggie. stage 3 will be around 11psi. one thing though, u will be changing ur air fuel ration but 1psi ur ECU should be able to accomodate it and actaully add the fuel. check it out on the dyno bcause im curious. I think u will actually notice the power in the mid and low range the most.

see top end u might only gain 1psi which is ok on our cars thats a decent gain. but mid range, u will not have to build boost at all, it will be right there. last night leaving the drive way after 2500rpm the tires went crazy, hit second and SPINNNN. usually i chirp second and my LSD grabs and goes. that was warmed up to. so check it out man but its easy to change back to stock so dont worry about ur warranty. i should be the one worrying, i have to bring my car there next week.

dude, use a golf tee! 3" pulley = 15.5PSI on a LSJ, so that cant be right unless your hooked up to a manual boost controller and its bleeding off the excess boost

[F.I.A.T]

so you're saying that you decided to alter the way your vehicle enters the boost table in an effort to gain HP without actually doing this with the aide of a A/F reading from a wideband. Not to mention you dont even have a EGT gauge to monitor your exhaust gas temps which have no doubtedly increased even a moderate amount.

[sheek360]

Originally Posted by F.I.A.T

so you're saying that you decided to alter the way your vehicle enters the boost table in an effort to gain HP without actually doing this with the aide of a A/F reading from a wideband. Not to mention you dont even have a EGT gauge to monitor your exhaust gas temps which have no doubtedly increased even a moderate amount.

Actually, I took boost away from first gear. So i can launch like a SI. I was getting excessive spin. Im doing great now! On my car at 6800rpm <200 rpm before fuel cutoff> I have piston protection engaged. So it richens out a bit. And I constantly moniter everything from cam angle to a/f ratio to knock to timing being pulled/given etc. If you guys cant atleast view a/f ratio or alter you ECU on your own <ie tuning> then you all should find a way.

[COMplex]

I'm trying to schedule a few runs on the local dyno with wideband tonight. I will do a regular couple of runs, and another couple with the hose plugged.

I'm pretty sure the pulley is larger than 3". I don't know exactly though.

I'm not sure if having all that power down low is a good thing. Wheel spin = not power to the ground...

More investigating tonight. OneSi, you should probably ask comptech. There may be a reason the hose is there in the first place.

[sheek360]

Originally Posted by COMplex

I'm trying to schedule a few runs on the local dyno with wideband tonight. I will do a regular couple of runs, and another couple with the hose plugged.

I'm pretty sure the pulley is larger than 3". I don't know exactly though.

I'm not sure if having all that power down low is a good thing. Wheel spin = not power to the ground...

More investigating tonight. OneSi, you should probably ask comptech. There may be a reason the hose is there in the first place.

the hose is in there because it belongs there lol, ive known a/f sniffers to be off by as much as .5 man. get a wideband. Or get what im running, the LC1. One sensor and it acts like a narrow providing the signal to ur ecu, and a wideband for for your gauge. You can also hook it up to wichever histogram program your tuner runs.