>There must be a difference since Vortech list both on their website ... http://www.vortechsuperchargers.com/...s/aircomp.html
under their "Race Bypass/Blowoff Valves"
and if there is a difference what is it ?

 

Bypass valves typically vent back into the system, BOV's typically vent to atmosphere.

Jose

 

Typically the actions are different.

Bypass valves are usually always open and when they sense boost in the intake manifold, it will close to allow all the boost to go into the engine. Most bypass valves are routed back to the intake. Some I have heard that they leave it open to the atmosphere, but then they should have a vacuum leak.

BOV are usually always close and only open when there is a pressure difference between the intake manifold (lower) and the intake piping (higher), then it will release the boost within the intake piping. This release can be vented to the atmosphere or back to the intake piping. BOV doesn't have to just vent to the atmosphere. They do sell kits where you can route it back into the intake system.

 

>So what are most of the people here using ?

 

IMO, the stock bypass valve from Vortech can handle just fine up to 11psi. Both LJ and I used this when we were maxing the S-trim and getting 600+rwhp, that is unless your stock bypass valve is leaking or malfunction. I think most people here are using this bypass valve.

However, when you are pushing more boost and going beyond the S-trim, I think those people are mostly running the mondo bypass valve and I would too.

Then a small number of people are running BOV for the supercharger and many of those have move the MAF post the BOV.

As for me, I have one pipe with the stock bypass valve and a pipe with a HKS SS BOV. My MAF is still infront of the supercharger. I would not recommend getting the BOV though, a waste of money. However, I am currently running the BOV just for the heck and it seems fine.

--Hugh

 

>thanks for all your help
I am using a T-trim with a smaller pulley on the head unit and the crank pulley is larger also (not sure the size got them from YellowZ28) .
I also ordered the Race Bypass valve from Vortech and I already have their Mondo Valve , but can't find a decent place to put it . So I will wait to install the Mondo valve when I install the intercooler .

 

I am going with Vortech's recommendation of using an upgraded blow-off valve if running 10+ pounds of boost or if the impeller speed will exceed 42,000 rpm.
This is probably conservative, but the blower head units aren't cheap either