Bypass/Blowoff valve thoughts

BrianFiebig

Member
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08 SPEED 3
I have a question or few about the whole BPV/BOV thing.
Seems to me that Mazda designed the car specifically for a Bypass, even if the actual unit seems to be considered to be a hunk of night soil. The rage seems to be to convert to a Blowoff, usually the HKS Super Sequential that every online shop seems to have.
Are there any documented (and I will want proof, as much as I trust butt-dynos...) advantages performance and fuel economy wise to going either way (or hybrid). My Speed is my daily driver, but I come from a LONG line of lead foots (I have boot-leggers in my family tree, and a 80 year old grandmother who refuses to use cruise control because its less fun). All this being said, I would like to know what route is better for a occaissionally hard driven car (I have a thing for ricers, I call my commute, especially on friday and saturday nights, Hunting Time). I wouldnt say no to a LITTLE whistle, but I am of the mind that compressor stall and the resultant way too fat condition to be a Bad Thing. Ideas? I know there are a few hybrids out there, but how many people have them and are satisfied, any performance/economy gains VS stock, Aftermarket Bypass, and aftermarket Blowoff.

Sorry this is a convoluted post.
 
I am not sure where you get "The rage seems to be to convert to a Blowoff". Lots of people have tried it and it doesn't work well without a tuning solution added as well. There are a number of choices for improved bypass valves, and if you are into funny noises, a SRI or CAI enhances the auditory experience, as well as adding significant performance.
 
BOV/BPV will not change hp or fuel economy. Unless you start upping boost/power and worry about it leaking there really isn't any reason to change except for sound.
 
Change it if you want, but do stick with a BPV. The car isn't designed for a BOV. Period.

The stock plastic bosche piece has historyically leaked on all of my SR20DET engines. I have always upgraded that piece due to it having issues holding boost over 12psi. Not sure if it is simply the design or the fact that it's plastic. But if it's not metal then i'm not very fond of it.

I haven't tested the the stock piece, but plan on it.

But do stick with the BPV.

Gmac
 
I had a bov installed on my old sti for about a month. If anything it hurts your fuel mileage simply because you will use the throttle more to avoid the annoying backfire that happens with all bov's. I have never been happy with the stock bpv on my old suby or on my new ms3. They both seem to have a tendency to leak in the higher boost ranges. on my suby I found a much better aftermarket bpv that would hold solid up to 30 psi. I haven't found the same quality bpv for the ms3.
 
You could be the first to run a blow-thru setup. Then have at it with the BOV.

Gmac
 
It's less BPV and BOV...I think those are basically two terms for the same thing. It's recirculated or vented to air that really matters. You can run a BPV vented to air and it will run like crap...or you can run a BOV recirculated and have it run fine (as long as you get it dialed in right).

I recommend the Forge unit. I have it, and it hasn't given me an issue yet.
 
It's less BPV and BOV...I think those are basically two terms for the same thing. It's recirculated or vented to air that really matters. You can run a BPV vented to air and it will run like crap...or you can run a BOV recirculated and have it run fine (as long as you get it dialed in right).

I recommend the Forge unit. I have it, and it hasn't given me an issue yet.

They are not 2 terms for the same thing. Bypass = air is diverted/passed back into intake system. Blow off = air is blown off into the atmosphere. The only time you can run a BPV on vent to atmosphere is on the hybrid systems (they do a little of both, and can be adjusted).
But I totally agree on getting the Forge unit.
 
Well, what I mean is that you can buy an HKS SSQ BOV and run it recirculated...and it would more than likely work better than a Forge BPV vented to atmosphere.
 
A BOV with a recirc adaptor. A BOV is not designed initially to Bypass hence the recirc valve, additional part to purchase when for $145 a Forge will do the same thing, look more stock, not rub on your hood and ultimately break. The only other I would recomend is the turbo full BPV, a little more $$ than the forge but has a stock sound.
 
Don’t go with a straight BOV, either go hybrid or BPV. Jan's Modified Mag has an article about this dilemma and they have a couple of graphs that show a car made for a BPV will loose top end boost if converted to VTA. If you want more proof I will scan the article when I get a chance.

Side note: Aftermarket BPV sounds like a super Mario game. I purchased the forge BPV, and now I have the turbo smart hybrid Duel BPV/BOV. I have not put the forge BPV for sale yet, but i can if anyone here is interested. (black finish)
 
Side note: Aftermarket BPV sounds like a super Mario game. I purchased the forge BPV, and now I have the turbo smart hybrid Duel BPV/BOV. I have not put the forge BPV for sale yet, but i can if anyone here is interested. (black finish)

Interested PM me!
 
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