cbpldc

I've heard cars with them, and I think they sound cool, but really, what's the purpose? Isn't that what my wastegate does? What can they do for me and my my 91 200 TQ 20V? Which one to get and where to put it? Anyone done this before? etc..

Enlighten me, for I am ignorant.

Chris

Audi2ptzero

Wastegate bypass's exhaust flow from going thru the exhaust turbo wheel. This controls how much over all boost is made. BTW there is something made now called a "pressure release valve". It is used on the intake side with a bpv, but it has a max setting so if you over boost the valve opens and is not controlled by vacuum at all.

BPV/BOV releases air pressure as you let off the throttle so that the throttle plate closes. When that happens the pressure the turbo is pushing gets backed up and ends being pushed back into the turbo compression(intake) wheel. The bpv releases that pressure so the turbo does not get damaged.

cbpldc

Cool. So not only does this prevent damage, but it sounds cool too! So, where would I put my BOV/BPV? I know Eric said that a TT one would work.

Chris

a4kasper

The BOV will go on the intake side just before the throtle body. You will most likely have to get this custom made and installed, thats what i had to do for mine.

AEGA4

Does it have to do with mixture?

Audi2ptzero

and not recycled back into the system before the turbo. When you use a bov the car tends to run rich right after a shift since the air that should have been there is not.

Mat Indukts Lambos

Best way to do a BOV is an adjustable one, like Turbo XS's model. Adjust it so it barely opens, so it won't be running so rich, since it won't be open for so long. The downside to this, is that you'll be shortening the life of your turbo by doing this, and it only sounds cool, no performance gain really. If you want the BOV noise safely, you can get this (http://www.lltek.com/aik.htm) intake, or one like it, with a good BPV (baileys, forge, turbo XS, OEM TT, etc), and the bypassed air will echo out through the intake. Granted, it won't be as loud, but your turbo will be around a lot longer...<ul><li><a href="http://www.4induktion.com/awetuning.html#b">BPV's---shameless plug--:-)</a></li></ul>

Stratocaster1422

http://dv.mistertam.com/ --&gt; The Great Diverter Valve Face Off!

Honda ETR

I'd love to see some actual fact behind the idea of the car running rich after a shift with a BOV, I doubt you could even sense it with a Lamda A/F. A BPV removes the air from the charge pipe also, how does the ecu know how much air is on etheir side of the turbo when you open up the TB again?? Oh and how does it calculate how much air is blowen off???

Audi2ptzero

injector pulse using the fuel map. When the bpv opens it just releases that pressure back to just after the maf and just before the turbo. So the calculation for the air still in the system still holds. If you blow it off instead of recycling it, the air is no longer in the system even though the ecu thinks it is and adds the set amount of fuel as if the air was there. There is no way for the ecu to know your blowing off the air to the atmos since there is no sensor reading it. BTW if you have ever done any real tuning you would know that going from 12.5 Air fuel ratio down to even 11:1 is a huge difference in power, you will also see a nice cloud of black smoke come out the rear of the car when it happens since that extra fuel is unburned and we all know unburned fuel = less power.