My new IC setup has a BOV connect betwwen the IC and Greddy Elbow. My Mechanic said he is gonna elminate the stock BOV off the intake.

Is this a good idea? I looked at some posts with aftermarket IC and BOV, and some still have the stock BOV that connects to air filter.

Does the stock one do a different job being where it's located?

 

well the stock twin turbos have 2 bovs so usually youd be replacing one with an aftermarket one...its the one that connects at the top part of the y pipe...youd just leave the crv one for the secondary turbo.

 

you can just take them out and cap off the holes. i think its 3/4 caps in the HELP section

 

He's pointed to the BOV that is a few inches off the stock intake box. I believe he is gonna leave the one on th y pipe. What does the Bov near the intake function in the seq system.

 

You're probably talking about leaving the charge release (TCR) and removing the stock BPV.

Obviously if you already have an aftermarket BOV it's pointless to keep the stock one there and it's just a flow restriction. Bin it - mine's been in a box for like 5 years.

 

WTF???

TCR? BPV?

What, do you just make up acronyms as you go?


The correct terminology is CRV (as in Charge Relief Valve) & ABV (as in Air Bypass Valve).

Now this I just didn't make up, I actually looked in the FSM (as in Factory Service Manual).

With 2k+ post, you should try it.............

 

I was wondering what he meant by TCR and BPV. I was like, o damn is there something else i should know?? LOL

 

I dont use any BOV's on my FD and all cars I work on I eliminate them from the system as they are not required, and are only another source of potential failure.

 

BPV, bypass valve.
TCR, turbo charge release.

Shorthand acronyms thrown around once in a while.

Now get off my ***.

 

Kidding right?

 

Well if they fail, it'd be like NOT having a BOV at all.

Seriously - if you value your compressor side, use a BOV. Besides, why would you not want to use one? They keep the turbos spinning between shifts and off-load periods - they are only good!

 

you want the BOV mounted as close to the throttle plates as possible to mimimize the "water hammer" effect (i.e. a pressure wave going back through the system when you shut the throttle quickly)....you want to relieve that pressure from the system as soon as possible

why Mazduh mounted the BOV on the y-pipe is another one of many blunders on this car, prob done to save a few bucks, like the cheap rubber IC hoses and plastic AST

mine is welded right to the Greddy elbow (with the "horn" pointing down)....thank you David Garfinkle

 

No not kidding.

They are only bad !

BOV's are only fitted as OEM noise reduction device when fitted in plumb back mode.

BOV's casue charge loss in piping and circuit cars can and have gone slower when fitted with a dump valve due to needing to fill back up charge piping upon re throttle application.

I eliminate BOV's on every car I own or work on be it Mazda rotaries or big hp 2JZ supra's, I have never had a turbocharger fail due to not running a BOV. On the other hand have had lots of techincal problems with cars fitted with BOV's and also general losses of performance

Have data logs ranging back 7 years on every format from Autronic to Motec to stand alone loggers that show no performance gains when running one of these stupid devices on a motor vehicle. Its one of the biggest single cons on the aftermarket performance sectors ever.

BTW F1 never used BOV's, even when allot of the engine suppliers had OEM road cars running with them........ The truth is they do very little if anything measureable for perfomance and they do absolutley nothing for increasing turbocharger life, in fact they do the exact opposite if they do fail or leak they can cause turbocharger overspeeding, probably why they were never used in F1

Fuel engergy is what keeps turbines spining either that or working in a complete or partial vacum, we dont and cant achieve partial vacumes but we do introduce fuel into the turbine section,once this is shut (on closed throttle) off the compressor slows dramaticaly BOV or not.

7 years and probaly 100 000km and up to 36psi boost speaking here across a plethora of vehicles. My SP FD RX7 only runs 16psi of boost but I have not had one issue at all in 8000km of driving and testing since removing BOV's infact only thign thats changed is that the car is more responsive and faster as a result.

 

We're not using anti-lag fuel spiking in 99% of the cars on here, so that's not really a valid option.

Can you post some logs, even in csv format, of a BO vs non-BO system that does NOT use a fuel-ignited anti-lag system?

 

Interesting reading.

I myself, running non-sequential twins, removed both the CRV and ABV and now have both of those 3/4 nipples spliced into my one Greddy Type-S Blow-Off Valve. Works well.

 

The fuel energy comment is not anti lag, it was not meant to read that way it was more meant that the only "normal" thing that gives a turbocharger energy is heat form combustion (temperature) and flow rate of gases over the turbine wheel. When you eliminate both these things (I.E. closed throttle and decel injector cut) amazingly the turbo slows down amazingly quickly with or without a BOV it makes no damn difference.

The admission of atomspheric particles or atmosphere slows any turbine system down very dramaticaly, the ONLY thing that can keep it sustained at any rate worth mentioning (aside form normal combustion on WOT) is running in a vacum and that my friends does not happen on anything but a lab type vacume system using in industry or a university. We rebuild turbo molecular pumps and I have seen this first hand

What does happen though in a negative way is that when running a BOV you dump all that hard work that was done by the compressor and loose all volume of compressed particles in the charge plumbing and charge cooler and this is a negative aspect since you have a lag to build this pressure back up on a re opening throttle. Turbine speed has greatly diminished since there is nothing to drive it since you lifted off anyway and the presence of atmospheric air pressure on the inlet of the turbocharger massively slows down the turbine/compressor anyway BOV equipped or not so its a net loss. This is why they were never used in serious competition at the top level.

The next biggest falicy is turbo failure, well I single handidly have proved that to be utter garbage but you dont need to take my word for it simple research will prove to you that turbochargers did not fail any sooner before the mass marketing of BOV's and they have not yet shown one scrap of evidence to prove what physics there is to back up their claims of increased reliability, they do however have a ton of scare tactics and adhominem argument to back up a baseless case though.

So far as practical fact I have no BOV's on my FD and it loves it I am constantly on 1.06kg/cm boost and have experienced no one single issue with many thousands of miles of hard driving and testing so far, car definatley has more pull between gear changes but so has every car that I have removed BOV's from.

 

Does it mean we have to call (what we've been calling the UIM) upper intake manifold the surge tank (as listed in the FSM) LOL I'd have missed a good deal on a surge tank if I hadn't asked for a picture. Happy new year folks. Jack
PS. sorry for not including the quote.

 

I'm sorry, i dont mean to be an *** but HOLLY WTF. This rice guy is killing me. I cant stop laughing. Charge loss from shift. What kind of car are you driving that you ahve to wory about that? My understanding is that the air surge from not having a bov can bend your fins on the turbo rendering them useless. All high performance circuit turbo cars have bov's. Dont be rediculous. My best case in point is pretty much every single rally car that has a turbo fitted to it. All you hear is bov. And dude, if you are having a problem tuning a bov, you probably shouldnt be tuning a car.

 

I'll have to agree with Hsitko. turbo surge is damaging to the turbo. a function of a BOV is to release the charge fast enough to keep the turbo spining the same direction while u engage the next gear. allowing you to minimize the acceleration gap between gear and spooling lag.

especially for street or circuit driving, no BOV = more likely for turbo to break and shorter life span.

 

when you shut the throttle, the pressurized air has to go somewhere

without a BOV, you have a "water hammer" effect, which can be very hard on parts

 

Sorry to bring back from dead, but... WRC level rally cars do *not* have blowoff valves!

I never hear blowoff valve, all I hear is compressor surge (giggle-giggle), throttle blade whistle (chirp, chirp) wastegates opening and snapping shut (chatter-chatter), and not so much anymore but not too long ago, good doses of anti-lag (BANGpoppopBANGBANGPOP).

No "whoosh"...

 

i was always under the impression that the BOV kept the turbo velocity up between shifts as was mentioned. I've also heard the wave coming back from the butterflies slaming shut can cause the blades on the turbo to completely stop. Whether or not it is incredibly harmful seems to be proven, but it does seem like this would lower the velocity a bit.

the point of all the boost being released and needing to refill the piping is a good point. Though i think that the turbo is still generating a certain amount of boost between shifts and that not all the air is necessarily released, which is why the boost comes up quickly between shifts.

Does anyone else have further feedback that have tried with and without BOVs? Preferably back to back.

 

I always assumed that when the ABV (using the FSM terminology) released, it didn't reduce the system pressure down to atmospheric pressure, but reduced down to some level of relative boost that the ABV was set for.

Of course, that really isn't how the thing operates since the valve actually is opened by system vacuum, not system pressure. The stock ABV starts to open somewhere between 4-7 inHg of vacuum and is fully open at 9 inHg of vacuum. What I don't fully understand is why it is controlled by the UIM vacuum? During shifting, I'm not sure that the ABV is open long enough, or wide enough to release all the pressure in the intake system.

This raises another question. For those of you have have used after market BOV that are adjustable, do you adjust them to try to mimik the stock ABV and start to vent at 4 inHg of vacuum or do you have them start to vent at some other value?

 

Most aftermarket BOV's close much sooner than the stock ABV (BOV). This actually gives better turbo performance and makes them much more responsive. Garfinkle and a few others have modified the stock ABV in the past to use a stronger spring to close earlier to provide that benefit.

I'm actually contemplating buying a used y-pipe and blocking off the CRV and BOV ports to run the stock twins. I have two extra sets of twins laying so it wouldn't be much of an issue if for some reason the ones I have die. However, if they do, I doubt it will be from running without a BOV.

 

hooray for thread revivals lol.

ive heard about professional cars not have BOV's but i assumed that was due to the advantage during the race making up for the cost of replacing turbo's more often.