They basicly do the same thing except the ATI valve recirc's it back to the blower and the Vortech bypass valve vents it

They both are open under vacuum and close under boost

 

I don't know, page 10 of the install manual says hook the line to a vacuum signal....

Boost and vacuum rise and fall together, the FMU measues vacuum. It implies the boost level from the manifold (sp?) vacuum signal and increasses fuel pressure.


JH

 

The vacuum hose goes from the FMU to the plenum . The plenum see's both vacuum and boost . Under normal driving conditions the plenum will see vacuum , and the FMU see's that vacuum and keep the fuel preasure at normal psi levels . Once boost starts to rise the FMU will increase the fuel preasure at a rate of [ 8 to 1 ] or [ 6 to 1 ] depending on the year your Vortech SC kit is . Earlier year kits had a 8 to 1 and 2004.5 and newer kits had a 6 to1 FMU . Hope that explains it clear enough .

 

Not really, but I looked it up somewhere else and found out you are right. You learn something new every day.
JH

 

BOVs vent to atmosphere. People like it because of the "shoosh" sound.
Recirculation valves "vent" back into the intake system.

The problem with BOVs, is they tend to vent air that's already measured (if it's mounted after the MAF sensor). When you vent measured air, it sometimes creates rough running and sometimes stalling. As the ecu sees contradictary information. ie.. air that supposed to be there but isn't.

 

vortechs vent before the IC and the MAF

 

Thanks for the discussion guys. This is exactly the type of info I was looking for.