Aftermarket BOV, performance or wank factor

[Roy]

Oh shit , i forgot.. they dont use one. :whip:

Im not saying i disagree, just that im nto so willing to subscribe to the Le Mans cars dont, so i wont.

They run close ratio boxes, so the things will always be on boost, the final drive, gear ratios are all maximised around this.

Secondly, some (i cannot confirm without going and reading up on them) run anti lag systems, if they are not allowed they sure as hell run rich on trailing throttle for similar effect as they pop and fart their asses off:)

Thirdly, the turbos these guys are running are not the same as the turbos you and i run. Looking at some US sites i have seen places that offer the bigger shafts etc, there are places that sell /use titanium exhaust wheels. For weight saving they use exotic materials for housings and also better stability at sustained high temp.

Fourth, many of the cars you guys are referring to run traciton control, so you effectively keep your foot buried when cornering and the computers sort out the rest.

Fifth, if you can tell me that in endurance trim these cars run 2.0bar the whole race, ill fall off my chair. Otherwise there is no denying that these race cars ppl are using to put forward an argument life their parts at regular intervals, turbos included.

So i fail to see why what your saying holds so much water. :confused: I suppose we arent looking at it the same way and we each have different experiences with it all.

Anyway...another silly little point is does the GT2 Porsche use a BOV:)

[Roy]

This time Twin GT3540R's where used on a Highly ported and tuned 13B engine.

Making over 1000BHP with minimal lag for a big circuit.

NO BOV's where used.. heh.. who give's a crap.. if you spent your money on a BOV or what not, thats your fault.

Whats a big circuit? Thats is stupid power, so how can a 13B spin such size turbos with as you say minimal lag????

If the thing has over 1000BHP, i am willing to bet money the thing couldnt do 20laps around Oran Park quicker then a Targa prepp'd GTR:) Does it have a crazy final drive ratio with a Guru/PPG gearbox?

...and one mroe thing, These race cars and drift cars typically run MAP sensors. Race cars exoctic gear liek Magnetti Marrelli etc and in Japan it seems the HKS ECUs are very common, both eliminate the need for AFMs.

Biggest thing with trying to balance my thing with no BOV and a bit of throttle would be the shudder/vibration of the engine as it chugged away with only part throttle :chairshot I noticed my car still does it to a much lesse extent when i have the BOV wound fully tight, somehting i no longer do.

So again no-one is wrong or right, the more you look at it i think you have to consider what you are running and your setup:)

[runn3r]

Too bad its already been done by RICE RACING, but not with 800bhp unfortunetly..

This time Twin GT3540R's where used on a Highly ported and tuned 13B engine.

Making over 1000BHP with minimal lag for a big circuit.

NO BOV's where used.. heh.. who give's a crap.. if you spent your money on a BOV or what not, thats your fault.

Well, if you wanna talk about cars like that, i do know one that uses a megasonic Bov and its in http://www.turbosmart.com.au/research.htm

Why is that?

Ive already said that if you do not mod your car, your standard bov works just fine but if you plan to have nice wooshh sound and ruin your car system, be my guest.

[Cefiro_PWA]

Whats a big circuit? Thats is stupid power, so how can a 13B spin such size turbos with as you say minimal lag????  

If the thing has over 1000BHP, i am willing to bet money the thing couldnt do 20laps around Oran Park quicker then a Targa prepp'd GTR:) Does it have a crazy final drive ratio with a Guru/PPG gearbox?

...and one mroe thing, These race cars and drift cars typically run MAP sensors. Race cars exoctic gear liek Magnetti Marrelli etc and in Japan it seems the HKS ECUs are very common, both eliminate the need for AFMs.

Biggest thing with trying to balance my thing with no BOV and a bit of throttle would be the shudder/vibration of the engine as it chugged away with only part throttle :chairshot      I noticed my car still does it to a much lesse extent when i have the BOV wound fully tight, somehting i no longer do.

So again no-one is wrong or right, the more you look at it i think you have to consider what you are running and your setup:)

No idea, im out of this talk

[Roy]

In fairness , how can you use a certain car as evidence of something then run off sayign no idea:confused:

This is an interesting discussion, though its gone well past talk about BOVs:)

[Sydneykid]

Check out this porsche Lemans engine..

 

Where is the BOV?

Oh shit , i forgot.. they dont use one. :whip:

Oh shoot, you had better throw your intercooler away, they don't have one of those either :whatsthat :whatsthat :whatsthat

[runn3r]

Oh shoot, you had better throw your intercooler away, they don't have one of those either :whatsthat  :whatsthat  :whatsthat

Hahaha

[archie01]

Interesting discussion fellas. It does get quite complicated though when comparing the engine set ups in race cars and trying to draw conclusions for engine set ups in street cars.

From a street car perspective, AFAIK the purpose of the recirculating BOV put in by vehicle manufacturers of MAF equipped engines is one of emissions rather than wanting to extend the life of the turbo. As emission standards became more strict in the 90's (and have continued to do so since), vehicle manufacturers were required to find ways to adhere to them. This is why many MAF equipped turbo cars that were made pre 1990's didn't have BOV's fitted (VL turbo's and i think Pulsar ET and EXA too but i think they used a vane air flow meter anyway)

How emission were being affected by MAF equipped vehicles that didn't have recirculating BOV's fitted was simply when the throttle was shut a small amount of compressed air would make its way out the front of the turbo inlet, past the air flow meter and out into the air box. This is the sound we hear when we get rid of the standard air box and fit an exposed pod instead. Since the air flow meter was 'registering' this amount of air that was exiting, it would also give the corresponding signal to the ECU (as if this air was entering) thereby causing fuel to be injected and a richer mixture to eventuate for that small period of time.

So back to the original question and limiting it to MAF equipped street cars only, IMO as long as the aftermarket BOV is of the recirculating type and can pass the same volume of air (or more) than the standard one then i see no reason why it shouldn't be used. I fail to see how it would improve performance however.

[Sydneykid]

As emission standards became more strict in the 90's (and have continued to do so since), vehicle manufacturers were required to find ways to adhere to them. This is why many MAF equipped turbo cars that were made pre 1990's didn't have BOV's fitted.

My 1989 Skyline has a BOV standard, oops it actually has 2 X BOV's standard:cheers:

[archie01]

Hehehe point taken

Let's make that pre 1988 then....it was just a rough guestimate of when stricter emission standards became operative.

[Steve]

LOL, Why do F1's need BOV? Man they arent even allowed for turbo.

They did, for around 10 years, THE MOST brilliant mechanical engineering minds in the world worked on them - yet no BOV - that is my point,

but hey, its impossible to argue with the 'street racer' thoery...

[Steve]

lets talk 1989 and nissan, cefiro, rb20det, NO bov - last year the model was run, R32 gtst rb20det plus bov - first year the model was run.

Probably around then that emissions became a focus point?

[Cefiro_PWA]

lets talk 1989 and nissan, cefiro, rb20det, NO bov - last year the model was run, R32 gtst rb20det plus bov - first year the model was run.

Probably around then that emissions became a focus point?

I had a 88 CEFIRO 5 spd, 3" , airpod,remapped ecu, standard AFM!!,12pounds boost on stock cooler..

the car was fine, shifted nicely, on*off acceleration and on*off boost was perfect.

i also had a R32 GTST and that had a aftermarket rice bov, i couldnt tell the differnce besides the CEFIRO sounded much better with its ancient flutter and the ricer R32 sounded like a crock of PSCHHHHHHHHH with its fully sic bov

p.s the cefiro from 90onwards has a BOV, the early models didnt.

[FATGTS-R]

As I mentioned earlier my 1987 skyline came factory without a BOV. I fitted one originally solely for the purpose of drivability. I actually came onto this forum the first time asking why it was stalling after a boost event and then clutching it and rolling to a stop.

I was told it was because I had an atmo venting BOV or none fitted at all.

I honestly didnt beleive it at first as I didnt think a dead standard factory vehicle would behave in such a way. But I fitted a $40 bosch unit and the problem disappeared.

I can understand the argument about emissions and crankcase gasses from the rocker breathers being vented to atmo through the air filter but maybe there was a drivability issue as well?

If I had bought the car from new and it was stalling like that I would of immediately taken it back thinking something was wrong.

On a side note which is supercharger related, not turbo, but related to BOVs, my best mate has a centrifigul Vortech supercharger which originally failed after less than 1,000kms and a replacement failed again after a few hundred ks.

The supplier ( CAPA ) claimed the problem was not with there units but that there was "not enough release cfm from the inlet tract when the throttle closed causing undue stress on the reciprocating components". The third unit was installed along with two big cfm venting BOVs and has ran without dramas for nearly 10,000ks and counting.

[runn3r]

They did, for around 10 years, THE MOST brilliant mechanical engineering minds in the world worked on them - yet no BOV - that is my point,

but hey, its impossible to argue with the 'street racer' thoery...

Im confused, thought F1 were not allowed for turbo and it was mentioned here in the http://f1technical.net/article4.html

Infos on F1 engines comparison with the road engines.

I do think bov is not required in a F1 car because of the weight? Besides the engine was expected to collapse at the moment the F1 crosses the finish line.

And btw, FIA regulation has changed the rules for year 2005. They expect an extended engine life.

http://www.formula1.com/insight/technicali...nfo/11/467.html

[psybic]

BUT, in context of reliability, yes, a indi car is needing reliability far, far more so than a street car.

If a turbo timer increased reliability, why dont they have them????

Reliablitiy for a few races maybe. How long before they need to rebuild there engines or turbos? I didn't know the race cars could kick around for 300,000kms on an oil change and changing the spark plugs everynow and then. I think you kinda have to agree there is a little difference in the amount of time we spend on turbo maintanence compared to a race car...

I think they don't need turbo timers cause they can actually wait around and cool the car down properly like you said. When I nip down to the bottle shop, I'm gonna boost up, as is my want, when I then shut my car straight off like the careless owner I am, its better to have the timer than not, in my opinion anyway.

[Roy]

They did, for around 10 years, THE MOST brilliant mechanical engineering minds in the world worked on them - yet no BOV - that is my point,

but hey, its impossible to argue with the 'street racer' thoery...

But do you think thhe following may help explain why they didnt run them?

Im not saying i disagree, just that im nto so willing to subscribe to the Le Mans cars dont, so i wont.

They run close ratio boxes, so the things will always be on boost, the final drive, gear ratios are all maximised around this.

Secondly, some (i cannot confirm without going and reading up on them) run anti lag systems, if they are not allowed they sure as hell run rich on trailing throttle for similar effect as they pop and fart their asses off

Thirdly, the turbos these guys are running are not the same as the turbos you and i run. Looking at some US sites i have seen places that offer the bigger shafts etc, there are places that sell /use titanium exhaust wheels. For weight saving they use exotic materials for housings and also better stability at sustained high temp.

Fourth, many of the cars you guys are referring to run traciton control, so you effectively keep your foot buried when cornering and the computers sort out the rest.

Fifth, if you can tell me that in endurance trim these cars run 2.0bar the whole race, ill fall off my chair. Otherwise there is no denying that these race cars ppl are using to put forward an argument life their parts at regular intervals, turbos included....

Im too young to know anything about 80s F1 cars other then what i have read. I recall they had active aero etc, but did they have traction control, or was that more late 80s when comuting power when thru the roof?

[archie01]

lets talk 1989 and nissan, cefiro, rb20det, NO bov - last year the model was run, R32 gtst rb20det plus bov - first year the model was run.

Probably around then that emissions became a focus point?

Steve, yes i would assume so too. I guess the first few years after 1989 would of perhaps been 'transitional' years with some models??

[Steve]

Roy, there are some good points there, to play devils advocate:

back in F1 turbo days, they did have to push in their clutch to change, and you can here the turbo flutter

Pop and fart - my car does that, but maybe its more to do with the fact that they will cut spark rather then fuel on trailing throttle - it helps cool the engine and reduces risk of overrun damaging the engine.

different turbos - hell yes, they are at the cutting edge, the technology they trial makes its way on to our cars - why havent they created cutting edge bovs if they are so relevant?

I am not sure how traction control would relevant to compressor damage by reversion, or change the throttle response for a tubo that has 'stalled' (note, I dont believe they stall, read the autospeed article)

Boost levels seemed to change as the years went past, it was not unusual for F1 to run 3 bar, up to 4+ in qualifying (they would wire their wastegates shut), with huge intercoolers. I am not sure what indi cars use, or lemans

You make some good points Roy, there are some very good points made through this whole thread - I just cant get over the whole issue about perfromance and reliability - if a bov is so vital, why wouldnt they use them - if it extends the life of the turbo, I dont see why they wouldnt use one, if it improves performance, I dont see why they wouldnt use them.

These motor sports are the test beds for developement of engines, the performance lessons find their way onto our cars - without them its quite possible we would all still be running push rod technology. I am not saying that the technology, dollars etc doesnt completely eclipse what we, as everyday users have - but things that work - work. If they dont work, they dont get used.

To summarise,

BOVs only became popular after manufacturers started fitting them - there is strong evidence to suggest this was for NVH and emissions (in afm equipped cars) purposes. No body used them before this point.

There are people, such as Bai in Japan, alot of jap workshops with D1 cars, guys I know here in aust, the likes of rice racer who have had none of the dreaded reliability or lack of power issues that are touted by so many to threaten a car without a bov. I havent had any of the dreaded problems I am supposed to.

F1 didtn use them,

Le mans - cars dont use them,

indi cars dont use them,

Rod Millen's 1000bhp 2L truck doesnt use one.

Simon Gishus when asked "What are some areas where people often make errors modifying their turbo car?" answered "the bov" and went on to say he lost time on the track when using one, that they are there purely for emmissions http://autospeed.drive.com.au/cms/A_1457/article.html very good article, not many people here, infact arguabley no one here could argue with the guy - his experience and results speaks for itself

Even Sydneykid said he doesnt allow the bov to full vent pressure

Sydneykid also used the example of the Sierra turbo failure as an example of why to use a bov - however the DJR Sierras at bathurst that didnt use bovs - dominated over Sierras with bovs (eg caltex)

Garret said they have never seen results to show the value of a bov

I have seen first hand aftermaket bovs that leak, limiting power and causing the turbo to overspeed - this could easily kill a fragile oem R33 turbo.

Plenty of people on this forum talk of the dramas they have found when fitting aftermarket bovs

There are threads on here detailing how to jack up the stock bov - to stop it from leaking

Mostly real life, track proven, research backed results

On the other side, you have

Bov companies - from the turbosmart webpage claim a BOV can help to:

"eliminate compressor surge when changing gears. Excessive backpressure is created when the throttle is closed during gear changes or deceleration, causing turbo cavitation. This is detrimental to the life of your turbocharger; however fitting a BOV will substantially improve this problem."

quite the opposite of Simon Gishus (who do you think has more performance cred? and who is trying to sell bovs?)

You also have the 'street racer' theory as pointed out by Runn3r - well, that would be assuming that street racers never are about posing - everybody look at me, I got a fully sick turbo car, goes psssst, its the loudest one on the market. hell even the bov companies like turbosmart advertise 'our loudest bov' - hmm, performance cred

Bottom line, if you feel comfortable using a bov, and uncomfortable not using one - then use one. Its a common mod to have.

As the thread asks, "aftermarket bov, performance or wank" well I just cant see the evidence to say its a performance mod. I have seen them cause dramas though - actual, real life, quantifyable dramas.

[Roy]

...lol, damn that was a post of aextraordinary magnitude. And seems to sum it up well:)

The on thing i cant get out of mind though, is another dodgy practical example:( Turn on your household fan and see what the blade does. It sits back. At work i have seen compressors do the same thing. So i look at my less durable plain bearing tubo and i dont like the thought of axial loads on the shaft. Are they reduced by use of a BOV? Perhaps, but id say most likely. Are they eliminated no. But i dont know of any other way to try and preserve my turbos thrust bearings.

PPL laugh at me as i change my oil every track day, meaning my engine rarely sees 1,000kms per sump of oil, all because im paranoid about turbo and bottom end failures because of oil temp and oil pressure (std oil pump with a 19 row cooler)

Im off to buy a lotto ticket. If i win im going to get to the bottom of this and about 10 other wives tales:)

...oohh, and one more thing:) Dont discount that regs dont allow them to run them?!?! Perhaps they could be seen as a way of bypassing restrictors, be electrically controlled...i doubt its the case but stranger things have happened.

...and traction control. Well they just gas the car, they are not balancing the throttle on corner exits etc. On gear changes i have already said that the fraction of a second in which they chnage gears means we are talking about bees d1cks:)