View Single Post
mark houghton mark houghton is offline
Registered User
 
mark houghton's Avatar
 
Join Date: Jul 2008
Location: Central Washington State
Posts: 3,776
Hi Erick,

Here's an eBay link to a BOV that can be confured to vent to atmosphere, or as a recirculation valve. It's the same unit I'm using as my main recirc valve now. Adjustable Turbo Blow Off Valve OR Bypass Valve : eBay Motors (item 160420879180 end time Apr-12-10 12:11:18 PDT)

I think you're already aware of this, but for posterity I'll repeat it: When I did away with the stock boost recirc valve and associated manifold, I left the AAV/decel valve connected pre-throttle body and left the vacuum line connected as well. Now, when shifting it vents to atmosphere. The only negative (if viewed that way) is that it causes a momentary richer mixture when shifting (AFR's drop to around 10.5 for a half second during shifts or sudden off throttle).
But another unanticipated thing (benefit?) is that on prolonged decelleration (within 2 to 3 seconds of no gas pedal) the pressure in the IC and associated pre-throttle body plumbing drops and is equal to the intake manifold; i.e., a slight vacuum occurs. With the AAV open, it will draw in a small amount of air (thus, I have a small air filter attached to the open end). That little bit of air leans the mixture and seems to prevent any exhaust popping. My vehicle does not gurggle or burbble or pop. But that might also be because I'm running with quite a bit more initial timing than most.

Hope this helps.
__________________
Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 04-08-2010, 08:30 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)