SC bypass valve question

[Snurfer]

got the supercharger put together on the truck!! pictures to come soon. my question is the bypass valve has a bung at the bottom of housing.... does that need to have a vacuum line placed on it and routed to the intake? or is there a specific place that it need vacuum from? and what psi would you guys recommend for fuel pressure at idle?

thanks again.

also the bypass valve is located on the SC. it is not inline.

 

[np24]

which engine and which supercharger are you using?

 

[Snurfer]

m62 off an xterra. 4.0L

stock injectors, mercur cougar throttle body. and stock MAF housing.

 

[TireIron]

You need to run a vacuum line to between the TB and SC to pull proper vacuum for the bypass. If it is run to after the SC you will not pull proper vacuum when you let off the gas to open the bypass correctly.

 

[rpcaster]

You need to run a vacuum line to between the TB and SC to pull proper vacuum for the bypass. If it is run to after the SC you will not pull proper vacuum when you let off the gas to open the bypass correctly.

Are you sure about this answer?
My M-90 by-pass is normally closed so my vacuum is pulled from the discharge side of the supercharger. This allows by-pass to open at idle/cruise.

 

[TireIron]

well it can be run to either, but a dedicated vacuum with activate the bypass a hair sooner because it wont have the boost pressing on it. Then again if you have an issue with loss of boost having the boost on the bypass may help to keep it pressed closed.

 

[Snurfer]

okay so i got my new gasket made for the SC to the plate. there was a tiny leak on the backside of the charger. still a little lost on this by pass valve though. with the vacuum line plugged in from the by pass valve to the intake pipe its closed at idle and if i throttle up it stays closed. but when i pull the vacuum line from the by pass valve it remains closed at idle and it opens when i throttle up. kinda confused?

also with my fuel pressure should i just run it at the stock PSI setting? the adjustable regulator increases 1:1 with boost.

thanks again for all the input guys i really appreciate it.

Chip

 

[TireIron]

The by-pass should run open at idle to let the air pass through it. It should be open with vacuum. So at idle or at cruising part throttle air will pass by the SC without full boost then when you get on it the bypass closes and you get as much boost as your pulley makes.

 

[Snurfer]

ran my feedline to the discharged side of the SC and she runs like a champ!! pulling 5 lbs at WOT. lovin it with the deep gears i can pull hills in 4th now that i couldnt do in 3rd. thanks for all the help with the by pass valve guys i really appreciate it.

 

[anupaum]

Ok, everyone beat me to it . . . I'm glad you got the bypass valve issue sorted out. It's nice to be able to climb hills in fourth gear, isn't it?

Good for you!