Aftermarket BOV (plumb back) make any performance differences?

[lup15]

Just compiling a list of mods that I'd like to have done and it seems that a lot of people change their BOV.

If I were to get one, it will be recirculated, so I wouldn't be changing it for the noise. However, is the stock BOV weak (leaks boost) or slow at closing at all? Its a few hundred dollars to change one...

Also why are people getting the Forge bov? Besides the fact that it replaces the OEM without any mods so ease of installation is a plus, the fact that you need to service it just sounds stupid. I dont know of any other bov you need to service.

Has anyone changed to an aftermarket recirculated bov noticed any difference in boost (spool up times, peak figure) and/or throttle response?

[Doug_MPS6]

LUP15, There are a million posts on BOVs on forums around the world. At least 50% of what is written is tripe. Many people don't understand the purpose of a BOV or how it functions. Look at all the idiots that want to put a BOV on a non-turbo car for example.

Most stock BOVs are 100% bypass, that is, all the air vented upon throttle closure goes back to the turbo inlet. The reason for changing to an after-market one is either: 1 - to get one that holds more boost; 2 - to allows partial or full vent to atmosphere (VTA) and/or 3 - to make a venting noise; 4 - to enable adjustment . Most stock BOVs lack any adjustment.

Changing from a stock BOV will not improve performance per se, all other things being equal. What it can do is solve the problems of a leaky BOV (rare); solve the problem of a BOV that is fine at stock boost but which leaks under boost above stock specs such as when boost control is tweaked up; or as a protective measure intended by the manufacturer against inadvertent boost spikes or deliberate tinkering.

But most importantly, it can enable a BOV to be adjusted. By doing so, the performance benefit that comes is not power, but arises by tweaking the BOV so just enough air is vented to Bypass to keep the turbo from stalling, while the remainder of the air under pressure remains in the plumbing and is thus still under some pressure so that there is less lag to full pressure build-up when you get back on the throttle - hence improved throttle response and apparent "quicker turbo spool up".

This should be YOUR reason to replace your stock BOV if it is not already adjustable, which I assume is the case seeing your handle tells me you have an MPS3. Set it up by screwing it in so you don't get backfires (if VTA or partial VTA), but not so far as to cause compressor stall - you'll feel it when you get there, so back off from that point. Make 1/4 turn changes and drive each time. It can take days. Best to take your time and not try to do it all in a day. I still believe the Turbosmart is the most user friendly around - it is a 3:1 BOV and the base is adjustable to you can get it sitting right to suit your plumbing. It can be fitted to the MPS3 in minutes. Don't drop anything down the intake pipe - block up the exposed flange with clean rag!

But beware of anecdotal tales from folks, who don't know much, about how it "adds heaps of power". If they say this then the odds are that they may not even know how to adjust one. If they get it right first off and report better throttle response and "more power" it is possibly just dumb luck - remembering also that better response often feels like "more power" too.

Cheers

[2XS]

Good job Doug

Upgrading the BOV to a larger item may be necessary for larger flowing turbos to allow the more air flowing to vent.

I know for a fact that the stock BOV can handle upto 22psi.

[Doug_MPS6]

2XS, thanks. I agree. I left that one off my description as I didn't think it was going to happen from LUP15's post.

In fact my BOV can't dump enough air due to build up of pressure in the 2m of plumbing on the turbo outlet side of the FMIC, and I still get compressor stall, hence my proposals for a second one. I've explored every other possibility and that is all that is left. My existing BOV dumps all it can off the throttle intake side of the FMIC just fine.

As explained before, my son has a blown V6 Holden (19psi for around 350Kw if I recall) and unbeknown to me had the same problem. He was stripping the teeth of the drive belts when the vanes stalled, and getting a noticeable "stumble" on lift off. A 2nd BOV (100% VTA) fixed it. Supercharged engines are strange cattle, whether with turbo or driven vanes.

PS: I love it................"I wasn’t born with enough middle fingers to let you know how I feel."

[TUFMPS]

I had an aftremarket one on my 3 and besides the sound i beleive it was the biggest waste of cash ever. went back to std and everything is better, mostly the way the car feels between shifts.. i'd consider going back to aftermarket if it was free but i'm not planning on it. I beleive there are no gains to be had from an aftermarket setup on a fairly std engine

[Jmac]

Have a look @ this - YouTube - ‪Mighty Car Mods - Blow Off Valves Mythbusted (SE02 EP03)‬‎

[MZSPD6]

Time to dust off the pushy lol

[lup15]

nice 1 jmac.

they should sell that kit and make millions

[2XS]

Update for a 20psi dyno run with stock BOV

Electronic boost controller set @ 20psi

As you can see, the boost is held, but, it has some irregularites.

[Grajy]

That vid was hilarious... lol