I see some confusion on terms here...

BPV (Bypass Valve) keeps the turbo from boosting before exhaust pressure supports it (reduces bogging)

BOV (Blow Off Valve) Keeps the turbo from over-pressurizing the intake system (prevents inadvertent damage)


You 'crush' a BOV to increase the spring pressure to hold more intake system pressure before venting.

 

I use the terms BOV and BPV interchangeable when referring to a stock Ralliart or Evo valve, because both are 100% recirculation. If I'm referring to a valve that allows for some percentage of vent to atmosphere(VTA), then I always use the term BOV.....I think others here on EvoM do the same....

 

I'd agree, that's what most people mean when they use those two terms. BOV = vent, BPV = recirc.



This thread re-kindled my interest in replacing the plastic stock BPV. After a bit of research I ordered the GFB T9033 from ERZ Performance. It arrived yesterday and I tossed it in. I haven't messed about with it too much but so far it seems like a great choice.

At $216 you'll be hard pressed to find a comparable brand new quality piece like this. It's fully adjustable from 100% VTA to 100% recirc. I opened it up a bit, maybe 20% at the most, and it sounds like your average BOV. I don't have my laptop with evoscan set up anymore, but I do keep my tactrix in my car all the time so I gathered a bit of basic log data.

Between the logs and the butt dyno I couldn't find any problems from driving with it open just a bit. I don't have a wideband so I'm not getting the most accurate of data since AFR is where this thing is really going to make a difference, but I did try a number of different types of driving to see if I could get my car to act up. I even tried slamming into the rev limiter. BOV went off, I shifted into third, and off I went without bogging down. Between driving like my grandmother and a bit of spirited driving my car acts much the same as normal. I chalked the slight increase in acceleration up to the "I got a new part!" placebo effect and I was still peaking at just under 20 PSI. I saw a 1 MPG increase in fuel efficiency on my way to work this morning, but with the weather changing I'll just consider this as no change.

If you want 100% recirc this is an excellent choice with a great price. If you want the BOV sound, which I can't blame younger guys for, this appears to be the perfect choice. I wanted to validate their claims that this works on our cars with VTA and as far as I'm concerned they're right. If there's anything truly amiss from running it slightly open I haven't yet noticed it.

My next test, and I'm sure some people will hate me for this, will be to see if I can attach a duck call to it for Halloween.


I did do some digging and found a thread from a while ago posted by another RA owner with this same BOV. He has links to youtube videos that show you what this BOV sounds like. I almost like it better than the stock sound which was nice and subtle.

https://www.evolutionm.net/forums/09...-ralliart.html

 

Fwiw, duck call bovs are hilarious. If I had a car that was more vta-friendly I'd run that **** year-round.

 

http://en.wikipedia.org/wiki/Blowoff_valve
Ah! I stand corrected.

I was confusing BPV with a waste gate [rolls eyes]...