buschman

I'm trying to figure out if there is any negative effect of using a BOV on our Procharger setups.

I have a friend who has an SS and recently got his new Procharger setup and got a Turbo-XS RFL BOV. He was trying to get a turbo whoosh instead of the Procharger flutter. It didn't work. But I did notice that his BOV acted differently than my surge. First off the tension is way heavier. My surge valve can be moved quite easily with your finger. His BOV has WAY more tension and you really have to press with your thumb to get to open. I had my doubts whether the cars vacuum source would be able to open this at idle. I was right, his BOV stays closed at idle and probably light acceleration.

The advantage is I bet his setup would start building boost sooner because his valve is normally closed. The downside is I've heard the whole purpose of the Surge/BOV was to relieve pressure and take strain off the blower blades.

I was hoping someone could shed some more light on this. I don't know what the defined difference is between a BOV and Surge valve. I'm also if running a BOV on our setups has a negative effect.

Any info on this would be appreciated.

Thanks,
Mike

buschman

I think I may have answered my own question, but in case anyone does a search and is interested here's what I found.

The BOV is bad for a supercharged car. Maybe not eminent danger, but it will wear the bearings in the blower down faster than a surge valve. Turbos don't run boost at idle so their BOVs are designed to stay closed so that they don't suck unfiltered air into the intake. Blowers do create boost at idle so if the BOV is shut the air is trying to go in two directions and starts to go out the way it came in, the compressor blades. This is how they strain the compressor bearings. I called ATI and they, without me suggesting what I had found, confirmed this.

My first big clue was a thread from this very site. Intmd8 made a very helpful post:
Thread 200623

I found this site interesting because it explains the difference between a Compressor Bypass Valve(aka CBV aka Surve Valve) and a Turbo Blow Off Valve( aka BOV aka Dump Valve aka Vent Valve):
http://wwwrsphysse.anu.edu.au/~amh11..._off_valve.htm

I found this site funny cause it's basically saying the term "Blowoff Valve" is being used incorrectly in todays FI industry.
http://not2fast.com/turbo/glossary/turbo_glossary.shtml

Just a few links to help you out. There is more info out there if you are willing to dig. But these were some of the threads that clearly hit the point home. Then the verbal confirmation from ATI sort of sealed it for me. If anyone agrees or disagrees by all means post up. But so far what I've read makes perfect sense to me. Logic seems to back this theory up.

Mike

p.s. I also heard rumor that ATI is developing a new mid level Bypass valve that should be out soon.

frcefed98

iTrader: (16)

BOV for Turbo
Bypass valve for S/C'ers

Vortech Mondo Bypass is an excellent, reasonably priced unit.
ATI Race Ready Bypass, very expensive, but badass
Vortech Race Bypass...low boost,hp Bypass

Blackbird

you got it. bov on blower cars are for showoffs that don't know any better.

I like bypass valves vented to the atmosphere.

they are wide open under vacum, slam shut under boost, and if you vent to the atmosphere you dont recirculate all that hot air.

win win

Ponyhntr

iTrader: (9)

These guys know what they are talking about!

NA$TY-TA

iTrader: (21)

Yes they do.. because they did it aslo.... i did also....... they suck on a SC car......

Kyle

Blackbird

never had a blow off here bypass all the way baby

cept for now, but wait, I have a turbo now

I8UR4RD

iTrader: (16)

good info. bringing it back.

NA$TY-TA

iTrader: (21)

FYI. As stated a BOV isn't for a SC setup....

Now a Bypass like ATI's Race Ready works on Both.
I had it on my D1SC setup way back when this thread was started and then had it on my S88 Turbo setup Stenod did for me.

Kyle

The Alchemist

iTrader: (19)

Ok, here's my question, is ther a downside to recirculating the bypass valve back to the intake for the procharger? If it's not making boost, it shouldn't be heating the air, plus my bypass is after my intercooler, so it should be sufficiently cool.

I8UR4RD

iTrader: (16)

you mean use it as a vacuum source?

vmapper

iTrader: (8)

There will be heat generated from the 'low' amount of boost still being pushed out of the blower, as its belt driven. And the head unit itself is a heat sink. Recirc, over and over, will warm the IAT.
Recirculating is quiet, to me, thats a downside.

This was my rant of Bypass (surge) valves vs BOV...
http://www.trafficjams.ca/Performance/BOVvsBypass.htm

NoGo

iTrader: (2)

I think if you recirc from after the intercooler it should minimize the heat sink issue. At lower flows your intercooler should drop the charge air to just above ambient - minus a few degrees due to the pinch.

BigBadWhitey

iTrader: (3)

I have a tial BOV on my car, but it stays fully open at idle......
I bought the kit this way, and it seems to work ok? Is there something done with the BOV to allow it to do that? My understanding is that it a BOV should remain closed until a certain boost is reached.