ok, im putting together a kit for my k20 ep3... i plan to run 7 and 10 psi off and on via hallman MBC... i was told that in my case to run a 7 psi spring because the MBC can only go as low as the spring... now someone told me to get a spring 2psi higher than wanted do to pressure drop from the intercooler (600hp precision). teh reason they say this is because if i get a 7psi spring and actually run 5psi, the MBC might not turn up enough to reach 10psi... i really want to know what wastegate spring to get?

thanks for the help

 

precision makes really good IC's that dont leak much.. get the 7psi spring.. you can always turn the boost up with the MBC.. (you would think it can go highter then 10psi)

 

no one else has feedback?

 

He speaks the truth. You can use a MBC to turn boost up past the spring level but not below it.

 

first, a MBC can raise pressure up past 10 psi.

second, if you get your pressure for your wastegate before the intercooler, you will have a slight pressure drop and see less psi at the intake manifold then the given spring pressure. If you pull your pressure for your wastegate AFTER the incooler, this should account for any pressure drop the intercooler would cause and your motor should see the psi that the spring is rated for.

 

^correct. I take my measurement from the intake mani for my wastegates on all my boosted cars so I get the actual spring rating vice the pressure drop from the intercooler.

Have been doing it for 4 years and it's worked fine for me.

 

how do you pull the pressure for the wastegate after the intercooler? im alittle confused?

 

tee your wg vac line into the brake booster line coming off the tob of the intake manifold (runs towards the drivers side / firewall)

 

you usually will have no trouble doubling the spring. So if you have a 7psi spring you can go up to about 14psi.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tallblondkid &raquo;</TD></TR><TR><TD CLASS="quote">how do you pull the pressure for the wastegate after the intercooler? im alittle confused?</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DJ Gurgla GSR &raquo;</TD></TR><TR><TD CLASS="quote">tee your wg vac line into the brake booster line coming off the tob of the intake manifold (runs towards the drivers side / firewall)</TD></TR></TABLE>


You would be better off putting a brass nipple on the cold side of the charge piping. Buy a 1/8 npt tap, drill a hole, tap the threads, put a tiny bit of JB weld on the threads of an 1/8" barb and thread it in.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adictionbass &raquo;</TD></TR><TR><TD CLASS="quote">You would be better off putting a brass nipple on the cold side of the charge piping. Buy a 1/8 npt tap, drill a hole, tap the threads, put a tiny bit of JB weld on the threads of an 1/8" barb and thread it in.</TD></TR></TABLE>

and hook that up to the wastegate?

 

also remember that boost controllers can only typically make double the psi spring and becomes unstable past that....

ie. 7psi spring can boost up to 14-15 psi and hold firmly! Im not saying u can make more....but genrelly thats the rule....

Decide what max psi you want to boost and get an appropriate spring that will hold when doubled!