jvog

So after doing some research, i have discovered that due to the way turbos build boost, most BOVs are designed to be closed at idle where as BPVs and BOVs made for S/C applications are designed to be open whenever the car isnt making boost. Anyone have any opinion/knowledge on this topic? My greddy is closed at idle, so I guess I need to ditch it and get a BPV and use it as a BOV...

Frostbitten

All blowoff valves and bypass valves do exactly the same thing. They all stay open during idle when the engine is under vaccum and they close once there is no vaccum or you hit boost. They really can be confused for two different types of valves but really they are all the same. The term blowoff or bypass is regarding to the way you use them. Bypass valves are just plumbed back into the intake while blowoff valves are vented to the atmosphere. For instance if you took a stock bosch bypass valve (which normally is plumbed back into the intake) and vented it to the atmosphere it would work just fine as long as you convert to a blow thru maf setup. That would make it a "blowoff" valve. It would also make the cool noise too. On our cars, blowoff valves are normally only used with blow thru maf setups or speed density setups with a map sensor. Bypass valves are normally used with a draw thru maf setup like what is used on the stock vortech kit.

jvog

Yes I know that they main difference is that the BPV recirculates air, but for some reason my BOV isn't opening with 20 in hg at idle...and that should be plenty.

edit: yes I am running a blow through maf..meaning the MAF is after the bov. Its set up the way it should be

Frostbitten

if its in there right then it may just be stuck.

jvog

Ok than maybe I am an idiot because I didn't know there was a backwards way of installing it lol...explain please. I am using a Greddy bov if it matters

Frostbitten

Do you have a pic? Most greddy blowoff valves use a welded flange. But I think a few still use the type that is attatched to a piece of hose. If you are able to flip it around then try doing that.

jvog

Yea mine uses a flange so its not backwards...

mustangman281

http://www.youtube.com/watch?v=iqQR5WUF9lc I don't know which style you have but this might help.

My advice is get away from the import crap and buy one made for real american cars like a vortech or procharger

If you were having problems with the stock bosh valve then I am thinking you have a problem with your vacuum source. I don't like the vacuum blocks because they can give false readings. I have 3 vacuum ports on my intake and only use 2 of them. I don't T vacuum lines for any more then 2 componets. My boost gauge and meth run off of one line and my FPR and mondo run off another.

Frostbitten

+1 im running my boost gauge from one source and the wastegate/bypass valve from another. The bypass valve will react better with a stronger source of vaccum.

jvog

I got it to work. My bov has dual springs so I took one out and now it opens. It whistles which makes it sound pretty cool lol.