Do i need a bov?

[ZMN BY U]

Hi mazdaspeed owners i bought a mbc from joe p do i need to replace the stock bov to improe the performance of the car.
What do you think? I also purchased the injen cai today im gonna run the car at 8psi for now until i can change the down pipe and the plastic piping that mazda put on the car. I allready have a custom exhaust 2 1/2 cat back exhaust with the stock mazdaspeed muffler ( didnt want the hassle from the police).

 

[I'm Allen]

Welcome to the board! I don't know enough to answer your questions. I'm still learning a lot about the car myself.

 

[SuperSpud]

well,, its a topic of debate right now.. some ppl's boost spikes,, then sinks about 2-3 psi when they up it with the joe p... some ppl say its b/c of the bov,, some just say its normal boost spike.. I had already ordered a turbo XS racing bypass 25 before I got my MBC... however,, I am running right at 10psi with my stock bov and not having any problems.. I would say that the stock one is fine to about 10'ish psi.. after that, you might need a stronger spring.. or it could be like the eclipse and leak.. WHO KNOWS!!!! maybe someone can be a little more help

 

[servoeyes]

Spud has a point, but so far it doesn't seem like there's a leak, from any reports. Some people with the MBC aren't tightening a nut properly to lock it in place...simple to do, simple to forget. As for adding performance, a bov won't do it...at all. It adds a mean sound, and if you don't recirc the air (or drive it properly while blowing to atmo) you'll stall. I think a good deal of this has to do with the ECU...it's just set too damn rich...but if you blow off instead of recirc, you miss that air at the MAF, and the car will go really lean to compensate for what it thinks is an overly rich state and stall...at least, that's as much as I can understand.

RX-Kevin can give a really good explanation of the whole process if you do a search. He's using the HKS SSQV with much success. JDMSam will also be using the SSQV, but he will recirc and offer a kit to just slap that biotch in there. I want to see how that sounds...yum!

Again...zero performance. But if you go higher boost, it'll probably be a good idea, just to prevent the possiblity of leaks. Hope that helps!

 

[twiztedjeckel]

get yourself a boost gauge before you go upping the boost

 

[Apexi]

make sure you dont have extra slack in the vac hoses goin to the joe p to prevent/get rid of spikes

 

[RX-KEVIN]

you don't have a boost gauge and you have cut the wastegate hose?

 

[Dexter]

i am running stock boost levels and still seeing this drop in PSI...

 

[kwiktsi]

i am running stock boost levels and still seeing this drop in PSI...

The stock valve will handle pretty much anything you guys put at it. It is not a standard spring, diagphram seat type. It looks like a motorcycle slide carb for those who know what I am talking about. It will not push open under boost, it is a wall until vacuum pulls it open.

The drop and spike are normal. Smaller, fast spooling turbos are always going to spike due to them spooling faster than the MBC and wastegate can react. I am now running a Blitz DSBC dual solenoid electronic BC and it still spikes about 1-2 psi minimum even with the gain (spool) turned all the way down and peak boost always varies 1-2 psi depending on temp and gear. It is the turbo more than the controller.
Joe

 

[Dexter]

well shouldnt it hold at the stock # of 6.9psi? i dont think they would publish the data as what it says at, not what it peaks at? like hell, if it peaks at 14 psi and drops to 7psi..."oh this car is running 14psi of boost!!" i dunno i really wish it wouldnt drop...