Just curious who is running in BOV mode instead of DV mode. Especially those running high boost.

Any noticeable differences?

I have run in both and never really noticed much difference except in noise but curious to know if anyone else noticed any differences.

 

I always run mine in BOV mode because I think it adds a great compliment to the turbo symphony.

Every time I opened the hood, forum geeks frowned upon it and gave lectures on how it makes the car run rich in between shifts. I never really noticed a huge difference...for me, as long as the BOV doesnt leak under a load, im happy.

 

Were you able to do this on a stock car?

 

I have heard even from some 951 guys that any car with substantial mods or boost should run in BOV mode but never heard or saw data supporting that statement.

Yes it does sound cool on shifts. lol

 

I run a HKS SSQV in BOV mode. The whistle is removed, so now it makes a whooshing noise on shifts. I also have a megasquirt which uses MAP, so I'm not losing any metered air. The valve reacts fast and doesn't leak; I've been pretty happy with it for years. People tell me that when I come by the stands on track it's quite noticeable when I shift.

 

I've got mine in DV mode (mine is the upgraded billet aluminum valve) and I actually do get a neat sound on upshifts (like a "fffftttsssttttssss". Not the stupidly-annoying ricer whistle you hear on your standard EVO/DSM/etc. I'll try to find a video.

You make me wonder though; I've never tried disconnecting it; could be a fun experiment.

 

If you want to use the Bosch style as a BOV, throw a mini filter on the open port. Any time you have decent vacuum(idle, light load, engine breaking) it will pull in air.

I've tried both ways, but keep in mind that unmetered air isn't the only reason to recirculate. Porsche cited transient lag as their main reason for doing it on the newer turbo cars.

 

Here's some video of my car; horrendous quality, sorry. But in the few times I was able to get some open track you can hear the DV going off (like a wishhhhhhh sound) -- even despite my warm-up pace. About 60% through the video I get a bit more open track; it's noticeable on the 2-to-3 upshifts.

https://vimeo.com/43432520

 

Yes, and no. the intercooler pipes were stock, but I had an NA coolant tank to run a dry turbo.

The BOV was short, and barely fit between the intercooler pipe and the coolant tank.

 

Huh?
sucking in air?
quicker spool?

last time i checked when i was running a MAP system with the stock turbo and no AFM, i had to run the forge 006 to atmosphere and on idle and vacuum it'll blow out extra air from what the turbo is moving though since the turbo is spooling and the trottle plate is shut.

if you run it as a BOV, you'll first need to block the hole from the maf where it use to connect to. And the car will run richer on idle or pretty much any vacuum situation where the by pass valve is open and recirculating air past the maf.

IICR this topic has been covered a million times.

There is no power gains from having it recirculating or dumped to atmosphere or even removing it to get a flutter sound.

 

I took a DV valve and running it in BOV mode. I am running a Link standalone which uses a MAP sensor. Its very loud. Did not notice any difference.

 

here's mine. billet dv going back into intake

 

Huh?
sucking in air?
quicker spool?

Quicker spool between shifts. Rather than wasting the energy stored in the intake charge by venting, it can be used to maintain the momentum of the compressor by recirculating. If you want, I'll track down the Porsche literature for an exact quote. For this reason, the new Borg EFRs have the BOV built into the compressor cover.

last time i checked when i was running a MAP system with the stock turbo and no AFM, i had to run the forge 006 to atmosphere and on idle and vacuum it'll blow out extra air from what the turbo is moving though since the turbo is spooling and the trottle plate is shut.

The Bosch style(Forge 006) is partially open any time you have vacuum in the intake manifold. If you are set up to vent it to atmosphere, you should have a small filter on the vented end, otherwise even though you have equal pressure in the intercooler piping and the engine bay, the air moving through the piping will pull air in through the open vent on the BOV. This is an off boost condition, your turbo is not generating any significant pressure. Most aftermarket BOVs void this by having stiff springs, but the Bosch ones have light spring for better response. They can do this because they cannot be opened by pressure in the intercooler piping like most BOVs can. They are operated entirely by vacuum.

Unscrew the top of you Forge sometime, and take a look at how it work. This should help you understand what I mean.


if you run it as a BOV, you'll first need to block the hole from the maf where it use to connect to. And the car will run richer on idle or pretty much any vacuum situation where the by pass valve is open and recirculating air past the maf.

I've never done it with a MAF, but it should run richer on upshifts(unmetered air leak), but leaner at idle as the engine has a new source of atmospheric unmetered air inlet.

IICR this topic has been covered a million times.

There is no power gains from having it recirculating or dumped to atmosphere or even removing it to get a flutter sound.

 

I never hear my DV. The only time I heard is when it blew off one of my hoses.

 

BOV

half the fun of having a map sensor