mengy007

I know I'm supposed to leave the small top port open and hook up a boost source pre TB to the side port. Can having both ports blocked off cause overboost? The guy that sold me the kit said it had a 7psi spring in it but last night when I took it out for a test, I saw it went past 7psi so I stopped and just babied it home. I will tried hooking up a vac source to it tonight and see what's different.

I guess my real question is: what does hooking up a boost source to the side port do? Isn't the valve suppose to open just from the exhaust gas pushing against the spring? Wouldn't the boost from the side port cancel out the push from inside the exhaust manifold? I'm confused.

urbansi

the wasegate still needs a vac source from somewhere, you can leave the top port open but the side port needs to be connected to a boost controller or a vac. line.

mengy007

I don't understand how connecting the sideport to a vac source will help with boost creep.

urbansi

think about it slightly before you jump to any quick conclusions
One restricts the pressure seen on the bottom side of the diaphram, the other adds additional pressure to the top side to 'equalize' some of the pressure on the bottom...

mengy007

please explain

0morgan@synapse motorsport

the wastegate has a diaphragm. on the lower port the pressure from the charge piping pushes against the spring when enough pressure builds up to overcome the spring the wastegate opens.

on the top port the electronic boost controller will apply positive pressure to the top of the wastegate, and when it reaches the desired boost level it switches positive pressure to the bottom to open, and then proceedes to switch back and forth at its programed duty cycle to maintain a constant boost level.

for the most part the exhaust gases dont push the valve open the boost pressure against the diaphragm opens the valve. the bottom port must always be connected or else the WG wont open. the top port is only neccessary on EBC that apply pressure to the top. manual boost controllers just restrict pressure so the WG doesnt see as much pressure as the system is producing.

alpha

If someone hasnt said it already. The side port needs needs to go to the compressor cover (if you can). The top needs to be left open. If you block the top off. The boost WILL spike

mengy007

What if I don't have a port on the compressor? could I connect the side port safely to a vac/boost source after the TB?

Bailhatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mengy007 &raquo;</TD></TR><TR><TD CLASS="quote">What if I don't have a port on the compressor? could I connect the side port safely to a vac/boost source after the TB?</TD></TR></TABLE>
yes that's fine. use a nice big line with nothing T'd off it. the port where the PCV goes is a good one

mengy007

thanks, I still don't get what boost does inside the side port, can someone draw me a diagram? I'm just curious as to how the insides work

mengy007

UPDATE: I got the side port hooked up. it's steady at 8psi now at full throttle. Plus after getting a downpipe and dumptube connected, i get much faster spool. I see around 4psi at 2.5-3krpm