Quote:
Originally Posted by Boltz.
Based on looking at the desing of this blowoff valve it looks (this is a generalization) like a standard blow off valve that is used backwards with a second sealed chamber for the piston and modded vacuum nipples for the reverse design.
Just by looking at the CAD photos, It looks like it would remain open under vacuum. Is there a spring in this BOV? What prevents it from opening under vac?
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Boltz- There is a spring in there to return the valve to the closed position around 3" of vacuum depending on the adjustment setting. But it does stay open under vac, which is why we always recommend re-circ as the #1 setup. We we're fighting for a long time with keeping it closed under vac, but come to find in application that users actually see the best performance with it open under vac.
The reason why there are so many vac fittings on the Synchronic unit, is because each vac fitting acts on a different amount of surface area. So you can actually move the vac signal around to tune the response for the each users setup. Pull-type valves are great, because they seal boost. They are horrible because they seal boost so well that the more boost you run, the harder it is for the same amount of vac to pull it open. And that is why, there is the boost-only port, to equalize the pressure on either side of the piston, so that the BOV always opens.