Should I add a BOV to my 1ggte?

[Cuzzo]

Well can a BOV actually disadvantage an engine when set up properly over a non bov engine?

Which ones are the most silent type, plumb back?

[stradlater]

Plumb back is the most silent.

People believe that putting a BOV on can cause you more lag because all that boosted air that's in the intercooler pipes is being let out every time the BOV goes off and hence has to be recompressed once back on boost.

I don't subscribe to that for different reasons.

Furthermore, if you run an AFM, a BOV (particularly a atmo one) can cause your engine to run rich momentarily when the BOV opens.

[love ke70]

doesnt a bov only let pressure out to a certain pressure, thefore you dont actually lose any boost in the pipes? ...

[stradlater]

Hadn't heard of that one love_ke, but it might be the case.. I think the more sophisticated ones might do that, I'm pretty well sure mine doesn't. :-)

[Norbie]

No BOV I know of works like that. They open when there's a sufficient pressure differrential across the throttle plate, and once open they vent ALL the boost pressure.

[stradlater]

the old style ones only vent until the throttle is opened again.

Which is fine really.

But I think there are newer ones that are a bit trickier, though I haven't looked into it.

[love ke70]

but the turbo is still spinning so it takes how many fractions of a second to reproduce that pressure?
and also, what about people who tighten the BOV to a stiffer setting to get that "fulli hektik butterflay effact y0"....

i dont see how a BOV can release pressure below the pressure that the spring is set to....
i may be looking at this the way crazy eyes looks at life, so feel free to slap me with a fish if im all wrong....

[Norbie]

You need to remember a BOV responds to two inputs: the boost pressure in the inlet plumbing (pre-throttle) AND the pressure in the inlet plenum (post-throttle). It is the pressure differential of these two inputs which determine when the BOV opens.

[stradlater]

He is right, yes, it's more a pressure differential rather than just the spring.

as for the turbo spinup time, I'll explain that one in my own special way to you some time love_ke...

[3T-GTE]

I'm with Norbie on this one. A good wastegate is all you need... IMO there are no benefits to running a BOV. I can only see the downsides to using one... so for my monthly post... see rant below...

I think I'll paraphrase what I've picked up from my friend Pete here... He is great at putting forward a logical argument... well certainly enough to convince me.

You only need to take a look at any successful race cars over the ages... remember the days of those 40+ psi F1 cars, none of them used a BOV... ... or the 720bhp Pikes Peak Audi Quattro's of the 90s, no BOV either

In regards to decreasing lag, I have investigated this for myself using data logs on various cars running Motec & Autronic ECUs, comparing the difference running with a BOV and running no BOV. and guess what.... no measurable difference in lag or any of the data log when changing gear... That’s with a resolution of 20 ms (0.02 of a second). I think you'll find others who have similar results.

As for "BOV's increase reliability", I also believe this to be another myth spread by BOV manufacturers. Just look at the 24hr Le Mans racers... these machines are running high boost for 24hrs or 5300km+ of racing!
Look at any number of the turbo winners, from the first turbo to win - 1978 Renault running 28psi all day and night, to the Porsche 962... all of which did not have a BOV, so I would have to say that reliability is not a problem not running a BOV.

You'd assume the cream of the world's engineers would have thought to run a BOV in the turbo hey day when it was used in F1, Touring Cars, World Sports Cars, Group B rally etc

There are quite a number of people from turbo gurus & suppliers who strictly suggest NOT running any kind of BOV.
If the BOV does not function properly, or leaks, it can destroy the turbo due to overspeeding... as the wastegate will not limit the speed of the turbo due to low intake manifold pressure not opening the wastegate... Something to seriously consider?

As for "why do manufacturers install them as standard"?
Probably as its less stress on intercooler pipes/coolers and connections They utilise cheap materials and in most cases plastic end tanks etc.
On good race cars you will see properly secured pipes (not with stupid sized agricultural clamps!) but with braces joining the pipes together as pioneered by Porsche back in the early 1970's on their 917 falt 12 twin turbo that raced with 1100bhp in many Can Am races and was visible on many many races cars of all makes after that.
All that kind of stuff is costly to make and labour intensive, and the expense of a bit less stress on a closed throttle a BOV (especially the Bosch ones) is a cheap alternative to proper engineering

Remember, air is very very light stuff, simple alternating flows as generated by the Turbo, wastegate & throttle plate in a non BOV system will never be of any magnitude great enough to cause any type of impellor damage or thrust bearing damage in a closed throttle situation.

It is a totally different phenomenon to experiencing a backfire in the intake tract under boost conditions which can cause Impellor damage, I think BOV marketers have decided to use these terms and apply them wrongly to NON BOV equipped cars in a closed throttle situation to "scare" enthusiasts into thinking they must have one of their products or else they will face imminent turbo failure.

To put some numbers to it, even if you were making 1000bhp worth of air flow with extremely efficient charge cooling this would result in a massive amount of 3kg (or thereabouts) of air weight acting against the impellor trying to escape out back past the compressor wheel in less than one second (if it could maintain turbine speed, which it does not!)
Even then, this peak load of 3kg is far less after 1 second in a 1000bhp application. I'd say that this is insignificant, and you would never generate enough force to cause damage in a closed throttle situation.

IMO, It’s easy to see that you have been sold a lie by people who really have no idea what they are talking about in regards to what merits their "performance products".

I would go as far as saying the potential failure of a BOV will at least cause you a performance loss (another area for boost leak) and at worst cost you a turbo failure due to overspeeding.

I'm interested to hear any other thoughts on this?
Cheers,
3T-GTE.

[Norbie]

Some very good points there. They say that if it's not used in racing, it doesn't work - and I find that generally to be true. The only major racing formula I know of using BOV's is WRC, and they use it as part of their anti-lag system.

[thechuckster]

... and a lot of that WRC hardware is electro-pneumatically operated so there's a lot of smarts behind the operation of the valves

[Pube]

Thanks for all your input, specially 3T-GTE. You have some very good points there and I have come to the decision to put the BOV back in the box and stack it on the shelf. My car/engine is hardly a high performer and as you have pointed out, even some of the high performing cars dont use a BOV! My dad also uses the phrase "keep it simple, stupid" and thats what I will actually do here!

[thechuckster]

also - having got my 18rte running - complete with the cheapest turbosmart BoV i could find - you quickly realise how irritating atmo BoVs are and that you can never quietly drive the streets again.

[JustCallMeOrlando]

The only reason I'm considering getting a BOV, is to quieten it down, which is probably one of the other reasons a manufacturer puts it on. My car is very loud when I get off the throttle at full noise, especially now I have no AFM