BOV position

[mattysaidso]

hey all,

jus a concerning question i have.

at the moment i am in the process of fitting up the intercooler piping for my rb25 (r33 gtst). now i have a blitz atmo BOV and i intend to retain it. now it was located on the return pipe from the std side mount cooler. as this pipe is no longer there i will be relocating the adaptor bracket on my new pipework. what i want to do is put my BOV between the cooler and where the piping goes through the driverside of the engine bay, so it is concealed by my front bar. this is to keep the BOV out of sight of the local authorities. what i am concerned about is, will the be an increased amout of lag produced because of the BOV's position from the throttle body? or will it make stuff all difference?

and yes i know i could get a plumb back type and put it right up close to the throttle body and have no legalissues. but i want to retain the atmo BOV and i also dont have the cash to replace it with a plumb back type at the moment.

cheers!

[magic1]

mine is tucked under the front guard and i have had no issues

[Sydneykid]

The idea of a BOV is to prevent the air from reversing direction when the throttle is closed. This has 2 effects;

1. It prevents the compressor being suddenly stopped (or run backwards) when the air rushes back the wrong way.

2. It keeps the air (in the intercooler and pipework) moving in the right direction ie; towards the engine.

So it would appear to me that #1 would be satisfied no matter where the BOV is located. But #2 is best satisfied by having the BOV as close to the throttle body as possible. That way none of the air is going the wrong way. This would mean better throttle response when the throttle is re-opened.

My 20 cents worth:cheers:

[mattysaidso]

thanx guys, just finished fitting up my intercooler piping and i have decided to use the std BOV.

i have heard that the small hjole in the bottom of the std BOV has a tendancy to leak boost pressure? is this true? and should i block it up?

cheers!

[doridori32]

If your having problems with BOV's just remove it, They dont do anything.

Petar.

[R33vit]

Hi Matty

Don't remove the BOV it's there for a reason. As for the small hole in the BOV, yes it does leak boost so you get a nice smooth transition between no boost and boost. For every day driving and Circuit work I leave it un blocked. For Drag racing I block it off.

[doridori32]

Hi Matty

 

Don't remove the BOV it's there for a reason. As for the small hole in the BOV, yes it does leak boost so you get a nice smooth transition between no boost and boost. For every day driving and Circuit work I leave it un blocked. For Drag racing I block it off.

Yes, the reason its there for is emmisions.

If you dont care your car makes the flutter noise then remove the utter jibberish BOV.

Petar.

[R33vit]

Yes, the reason its there for is emmisions.

If you dont care your car makes the flutter noise then remove the utter jibberish BOV.

Petar.

Petar try reading this

The idea of a BOV is to prevent the air from reversing direction when the throttle is closed. This has 2 effects;

1. It prevents the compressor being suddenly stopped (or run backwards) when the air rushes back the wrong way.

2. It keeps the air (in the intercooler and pipework) moving in the right direction ie; towards the engine.

Its not just for emissions boy :kick:

[doridori32]

Petar try reading this

 

 

Its not just for emissions boy :kick:

Please... Even sydneykid knows what im talking about.

there is NO test proven that they do ANYTHING.

We have done many tests on our autronic sm2 with datalogging and testing how much damage the air can do.

Pushing many turbo's past 25+psi and no damage with TESTS to prove the air didnt damage the turbo.

Sydneykid knows this himself, and i bet his race car DOESNT have a BOV.

Sierra Cosworth's pushing 45+psi down mount panarama screaming with there external wastegate's and did NO damage.

Please , get your facts right before posting crap on the forums.

Petar.

[R33vit]

Please... Even sydneykid knows what im talking about.

there is NO test proven that they do ANYTHING.

We have done many tests on our autronic sm2 with datalogging and testing how much damage the air can do.

Pushing many turbo's past 25+psi and no damage with TESTS to prove the air didnt damage the turbo.

Sydneykid knows this himself, and i bet his race car DOESNT have a BOV.

Sierra Cosworth's pushing 45+psi down mount panarama screaming with there external wastegate's and did NO damage.

Please , get your facts right before posting crap on the forums.

Petar.

LOL

What ever fool

[doridori32]

LOL

What ever fool

Who's the fool who the smart ones are laughing at?

Does this mean everyone here is a fool ???

http://ausrotary.dntinternet.com/forums/vi...der=asc&start=0

NO IT DOESNT.

BOV's are just a market strategy, and mostly used for promotion.

At the end of the day i think it comes down to what you like the sound of.

There's never been any hard proof of BOV effectivness by any of the BOV manufacturers in regards to "protecting your turbo".

In response to the "cars come out factory with BOV's now, they must be there for a purpose" call, they are there for new and more stringent emissions & noise reduction laws-plain and simple, they are another form of muffler. Can you imagine a 40+ year old taking the latest SAAB turbo for a test drive and fluttering out of the dealership. Unlike us he wouldn't have a clue what that noise would be and that doesn't amount to good sales figures.

A mate of mine who owned an S13 ran 16psi on a standard turbo (aftermarket cooler) for over 4 years. This things flutter was awesome, loud and long. We pulled it off to fit his upgrade and the thing was immac-no play what so ever, seals perfect.

They dont open fully when your loaded up with revs and flat shifting so where's their effectivness then? You only get that long drawn out pssht when your lazy shifting.

Personally i think BOV's are just another marketing ploy.

If anyone can prove they work, tell the 16 x LeMans 24hr winning engineers at Porsche.

24hr track car, twin KKK K27 turbo's-no BOV"s!

Here's the video of the car-well worth the 12mb, a must in any car buffs video collection. Tiff Needle doing what he does best!

The turbo flutter is nuts -

http://www.lad.lv/~martini/porsche/Videos/...Porsche_GT1.asf

[doridori32]

People actually have proof they dont do anything, not proof they do ANYTHING.

Petar.

[Skyrine-Dave]

I think i read somewhere that Fred Gibson said the reason why their cars didnt run BOV's was because they didnt expect the throttle to be closed that often

Therefore a BOV may be better suited for a road car where the throttle body is open/closed a fair amount of the time.

There is no need to come on here and act hostile and 'Mr Know it all" towards people with their own opinions... Maybe you should go tell nissan they are teh suck for putting stock BOV's on most of their turbo cars

but meh this argument is done to death. Each to their own. I will be using one on my car.

[StuiE]

I too beleive that a BOV doesn't do anything for the life of a turbo

http://www.autospeed.com/cms/A_2385/article.html (ok not everyone trusts autospeed, but there is a bit info in it....)

Blow-Off BS

Someone needs to learn more about turbo cars before knocking the usefulness of items such as blow-off valves. Anyone with half a brain knows that it isn’t a performance upgrade - it is more for the longevity of the compressor. Oh, and those SUPA DUPA expensive blow-off valves you refer to are able to hold higher boost pressures than factory ones can. Go back to school and the leave the commentary to the experts.

Big Blue

USA

We are yet to see solid evidence that a blow-off valve improves compressor life. One expert tuning shop we know has measured pre-throttle pressure spikes that were CAUSED by an aftermarket blow-off valve... Furthermore, you’ll be interested to note that Subaru fits a (closed-loop) blow-off valve to their production engines for the purpose of reducing induction noise. This is stated in the factory workshop manual.

If you have any proof that blow-off valves extend turbo life – as opposed to theory – we’d love to see it. Meanwhile, it’s a great way for many “experts” to make a few dollars...

Of course, if a blow-off valve is leaking under boost pressure then – yes - it’s a good idea to replace it.  

Also remember the RB20DET NICS (and probably RB20ET too) and RB30ET don't have BOV's stock...

[doridori32]

I think i read somewhere that Fred Gibson said the reason why their cars didnt run BOV's was because they didnt expect the throttle to be closed that often

Therefore a BOV may be better suited for a road car where the throttle body is open/closed a fair amount of the time.

There is no need to come on here and act hostile and 'Mr Know it all" towards people with their own opinions... Maybe you should go tell nissan they are teh suck for putting stock BOV's on most of their turbo cars

but meh this argument is done to death. Each to their own. I will be using one on my car.

Show me some proof.

Ive seen enough.

[doridori32]

stay on topic!! Ive already answerd his question

[Roy]

Comparing race cars to road cars is can mean the wrong assumptions are made. The Porsche you refer to is a race car that would is able to be flat shifted with the ECU retarding the ignition momentarily as the dirver reaches for another gear.

Im of the school of thought that BOVs are needed. I drove my car without a BOV for about 3 months, then when i threw a BOV on it there was a noticeable difference to how the car drove and spooled...perhaps a wiser observation is does the 996 Porsche Turbo or GT2 have BOVs:)

As for wear and tear on the turbo, there is perhaps merit to this arguement.

[doridori32]

Comparing race cars to road cars is can mean the wrong assumptions are made. The Porsche you refer to is a race car that would is able to be flat shifted with the ECU retarding the ignition momentarily as the dirver reaches for another gear.  

Im of the school of thought that BOVs are needed. I drove my car without a BOV for about 3 months, then when i threw a BOV on it there was a noticeable difference to how the car drove and spooled...perhaps a wiser observation is does the 996 Porsche Turbo or GT2 have BOVs:)

As for wear and tear on the turbo, there is perhaps merit to this arguement, but my biggest objection is the pressure spike in cooler pipes may help blow off hoses.

You might be right, but this might be you still have some factory emmisions stuff on your car.

all of the car's we have built use NO BOV's , 25+psi and no drama's.

Each to there own

Petar.

[Roy]

Thats the thing, each person has their own thinking. One thing is when ppl talk about stalling or reversing the turbo...if you think about how a turbo works, id suggest its the air in the inlet tract being chopped by the compressor. As with the thing spinning at 100,000 rpm and air spinning the turbine, there is no way that the inlet air and closed throttle body will stop and reverse the flow of the turbo.

On paper it may increase the torque between the turbine and compressor, but with the throttle body closed for gear changes etc then you wont have the same cfm thru the engine anyway...so, lol, each to their own, but not running a BOV certainly doesnt reverse the flow of the turbo, but i suggest it does slow the rpm of the shaft.

In an ideal world you want the turbo to keep spinning at the same rpm as when you were on the gas making boost. What will slow the turbo is the closing of the throttle body, meaning less combused air thru the engine, and also the fixed volume of the inlet tract which is now trying to be pressurised by the compressor.

What i would think as being ideal is that the atmo BOV effectively make the inlet tract an open system with the turbo being an air pump flowing air to atmosphere resulting in the turbo maintaining its kinetic energy in the compressor. The when the throttle is cracked again you have a turbo already spinning at 100,000rpm resulting in plenty of cfm and boost...thats ideal world, sadly there are trade offs:(

[mattysaidso]

Hi Matty

 

Don't remove the BOV it's there for a reason. As for the small hole in the BOV, yes it does leak boost so you get a nice smooth transition between no boost and boost. For every day driving and Circuit work I leave it un blocked. For Drag racing I block it off.

but will blocking up this hole cause any damage to anything? cause i have an flat plate to block it off that was part of my old setup. just thinking that i might block the small hole off and take it for a run just to test the differences, but i dont wana do any damage to anything if i block it up....

cheers!