bov,diverter valve

[vr6dubnut12]

sorry if this is a stupid question but what are the differences between a bov,diverter valve and wastegate dont they all do pretty much the same thing?
thanks

[TBT-Syncro]

Quote, originally posted by vr6dubnut12 »

sorry if this is a stupid question but what are the differences between a bov,diverter valve and wastegate dont they all do pretty much the same thing? thanks

DV and BOV do the same thing -allowing air to be vented out of the system when you lift off throttle. The difference is that a BOV is typically venting that air to atmosphere, and the DV is venting it back in to the intake tract.

a Wastegate does something completely differnt- it controls how much boost the system makes. once the set level is acheived, the excess is vented in to the exhaust tract.

[vr6dubnut12]

cool thank you so much

[Neptuno]

I like to revive this thread to ask some other questions about the DV and BOV as they relate to using internally waste gated turbos.

Here we go:
In Internally waste gated turbos also using the a volvo CIS fuel management, I have been told that a diverter valve should be used and ussully placed in the pipe between the TB and the IC. That was a compromise so that the tutbo does not over pressurize and that nothing bad (like knock) happens.

So can someone set me strait? I have Corkys' book, but there is no information that I can really understand about placement.

I should also mention that my set up is the based on the old calloway piping for intercooled turbos. I will be using the Volvo FD, Audi 5000 WUR and internally waste gated T3/T4 on an ABA/JH Hybrid

TIA,
el t.


Modified by Neptuno at 1:05 PM 1-23-2009

[PhReE]

Ehh, internal/external wastegate has nothing to do with using a BOV or DV.

The engine management does, as cars with a MAF meter the air right as it goes in and if you use a BOV then it vents an un-known amount of air out of the system (after it was metered) and that will throw the fueling off.

Map based cars measure the air later, and so you can use a BOV.

Also a BOV/DV have NOTHING to do with boost pressure control. The wastegate does that.

FWIW I run a BOV on my MAF based car.

[Neptuno]

I do understand what you are saying, thus I realized that I did not give some information needed for my question.

I am using the volvo CIS for fuel management and I needed an aswer as to the placement of the diverter valve. You have already ilustrated that the air fuel ratio would be very hard to quantify by the MAF with a BOV and that makes absolute sense to me now.

Thanks for that. Can someone help figure out the rest? DV location maybe even connections that need to be made?

TIA,
el t

Quote, originally posted by PhReE »

Ehh, internal/external wastegate has nothing to do with using a BOV or DV. The engine management does, as cars with a MAF meter the air right as it goes in and if you use a BOV then it vents an un-known amount of air out of the system (after it was metered) and that will throw the fueling off. Map based cars measure the air later, and so you can use a BOV. Also a BOV/DV have NOTHING to do with boost pressure control. The wastegate does that. FWIW I run a BOV on my MAF based car.

Modified by Neptuno at 1:11 PM 1-23-2009

[PhReE]

So, you need to route it so that the DV re-inserts air AFTER the flow-plate for the CIS, and so that the air comes from before the throttle body.

intake -> cis flow plate -> dv air return -> turbo -> intercooler -> dv air source -> tb