I've got a theoretical question about BOVs--particularly the kind shipped with the Vortech SC. If the drive belt for the blower were to break or be intentionally removed, would the engine be sucking in unfiltered air through the discharge port of the BOV rather than from the filter attached to the blower itself? This would make it inadviseable to drive without a fully functioning blower for any more than a short distance. I'm hoping that the BOV discharge port is isolated from the engine side of the intake piping and that intake air can only come from upstream of the port when there's no boost. No conjecture please--only accurate info regarding this issue.

 

The valve should be closed except for heavy vacuum conditions like deceleration in which case it would be impossible for it to suck in unfiltered air.Now this is assuming this valve is indeed a blow-off valve and not a by-pass valve.A by-pass valve will open up at idle and you can suck in unfiltered air.This is why by=pass valves are recirculated back into the intake track of your supercharger or turbocharger.

 

The Vortech literature refers to it as a bypass valve in one place and a BOV in another. The BOV 'exhaust' port is open all the time except when vacuum drops to 4" or less and all the way in boost. So, during idling or normal driving, the BOV is blowing off continuously--hence the telltale whistle. The Vortech BOV does not recirculate through the blower. Is it possible, therefore, for unfiltered intake air to go backwards through the BOV port directly into the engine if the blower, for any reason, isn't blowing?

 

The valve should not open unless there is pressure on it not suction or vacuum and you adjust the BOV so it doesn't leak while on boost and only open when you shift and the throttle closes resulting in the pressure backing up in the intake and then being released by the BOV. Disclaimer I am not an expert as requested.

 

I think you're referring to the kind of BOV found in turbo applications. The BOV, or whatever it is, in the SC kits opens and closes based on the vacuum or boost pressure in the plenum--transmitted to the BOV via a vacuum line. Under more than 4" of vacuum, the BOV is constantly shunting pressurized air from the blower out the BOV port into the environment and keeping it out of the engine. So, if the blower isn't turning because of a belt problem or because I intentionally disconnect the blower drive belt, the BOV port stays open all the time (only vacuum in this situation, no boost). My question is whether air can now flow backwards through the open port and directly, unfiltered, into the engine. If that's the case, it isn't safe to drive around very long with a disconnected or malfunctioning drive belt.

 

I've run my Vortech'd G35 w/out a belt for weeks and had no issues.

 

I cannot see how your BOV valve is openened at all times in this situation. Unless it uses an insanely soft spring (some do), it won't open till there is boost present. Some BOV's with very soft springs still open under vacuum, but the opening is so brief, I would not worry about "unfiltered air" entering at all.

 

What you're describing is different than the BOV in the Vortech which should properly be called, I guess, a bypass valve because it allows the constantly pressurized air from the blower to bypass the intake system by venting it outside. This vent only closes when the throttle is put down and vacuum drops closing the bypass and immediately creating boost. The question is whether retrograde flow through the always open vent happens when the blower's disconnected. One may not notice an effect on the engine immediately, but if dirty air can get into the cylinders, that's got to be bad over a short period of time.

 

How do you guys route the belt if you want to disconnect the blower pulley from the loop?

 

The Bypass- BOV that come with the Vortech stays open under vacuum and is adjustable to close at different vacuum levels or [0] vacuum . If your going to have the cog belt off or the blower off also [ Like I do now ] I would suggest putting a filter on it if you do alot of driving . You could instead , disconnect the IC pipe that is on the IC side of the MAF pipe , the one thet bends down behind the blower . Turn it out towards the fender and put a piece of foam filter like they use on shop vacs or simular .It will breath better this way . I'll be driving mine with out the blower for 3 or 4 weeks till I get the blower back from Vortech.

It will run very rich if you give it to much gas . You should reset the ECU to let it adjust . Do it again after the blower goes back on

 

Sounds like the Bypass/BOV is in an open state more than a closed state..It closes when manifold press reaches a specific vac pressure and above and is open below that level which has to be a considerable amount of driving time..If it's open a lot isn't air entering it or does it have a check valve to prevent it from breathing in? What am I missing here? Also a vent valve seems to be a better description of it's function than Bypass or BOV..

 

Booger,

I currently have my Split Second box out of the car....turns out my problems were diagnosed to be the box. The location Vortech recommends installing is not a good place. I have a little water intrusion that made its way into the box and shorted out several connections. I am calling vortech as this should be a warranty issue. I will then extend the harness to mount inside the car.

If I disconnect the cog belt and put filter on pipe like you said above, will I be able to "get on it" like the car was stock?

 

WHen the blower is hooked up and turning , under normal driving its open and air is coming out of it . When you give it gas , vacuum drops in the plenum and the BOV closes allowing boost to build . If you have the cog belt off , or the blower off . The BOV will still work the same but will be sucking in air instead of releasing air

 

If you have bigger injectors , it will run really rich and maybe bog down . If you have stock injectors and you disconnect the IC pipe before the MAF , it should run like stock . You dont have the SS box hooked up and the blower hooked up , as long as its breathing good enough [ not trying to suck air thru the IC ] it should run like stock . Reset the ECU though

 

Will it reset buy disconnecting negative terminal on battery correct? I have stock injectors. I will probably use some filter/mess screen and duct tape it on pre intercooler until vortech ships me my new box.