To blow or not to blow.... ?

Hi mates !

the newbie I am is wondering, what's the benefit of a blow-off-valve ?

I mean, ok there's the strange sound, but what else ?

Is it much work to fit one on a stock engine ?

Thanks for your enlightenments

An externally vented BOV has no benefit, it only makes the car sound like a bus door is opening when letting off the throttle under boost.

You can fit one to a stock engine, the stock recirc setup is only there to reduce annoying noises.

if you do get one get a hks ssqv mint

Hi mates !

erm, Ni....

I find with my Blitz BOV, it only makes a noise if you want it to, so suddenly letting go of the throttle does it, but not if you do it gradually, just makes that quiet chattering noise.

if you do get one get a hks ssqv mint

Quite honestly shane, the HKS is the worse sounding BOV i've heard, I hated the one on mine. It sounded like a mouse farting

This one is my favourite, old school Blitz:

I find with my Blitz BOV, it only makes a noise if you want it to, so suddenly letting go of the throttle does it, but not if you do it gradually, just makes that quiet chattering noise.

Thats how all vent to atmposhere BOV's sound. Let off under higher boost and it'll operate (the whoosh, or nouse fart/bus door sound), let off under light boost and it will result in compressor stall which is the air being forced back though the air filter due to the BOV not venting. When you hear chatter, it's not the BOV making the noise, it's air being pushed back through the air filter by the compressor stalling.

Quite honestly shane, the HKS is the worse sounding BOV i've heard, I hated the one on mine. It sounded like a mouse farting

 

This one is my favourite, old school Blitz:

 

Rubbish noise, I hate mine with a passion.

Hi mates !

the newbie I am is wondering, what's the benefit of a blow-off-valve ?

I mean, ok there's the strange sound, but what else ?

Is it much work to fit one on a stock engine ?

 

Thanks for your enlightenments

Noticed you are from France, is yours a Japanese or European model Supra?

I think I like the Blitz one.... very much

So if there's no benefit, are there any drawbacks ?

Nic, I'm buying an uk-spec at the moment, J-spec are too much of a mess to get registrated in France

are there any drawbacks ?

Yes on a UK spec Supra there are drawbacks

The stock blow off valve recirculates the air back into the intake. The UK Supra uses a MAF (Mass Airflow) sensor, if you fit a BOV that vents to atmosphere it will screw up the air/fuel mixture.

Options are to either leave stock BOV fitted, or fit an aftermarket BOV and vent this back into the intake system. Blitz and HKS both make adapters to recirculate the air, but this will make the BOV almost inaudible.

Waste of time IMO on uk car and will add nothing. To much hassle for no gain.

Quite honestly shane, the HKS is the worse sounding BOV i've heard, I hated the one on mine. It sounded like a mouse farting

 

This one is my favourite, old school Blitz:

 

 

 

Now that sounds like a bus door

So if I got it right a bov is about no use on a uk supra ?

Plus it's an auto gearbox so I guess I couldn't "play" with it that much anyway....

An externally vented BOV has no benefit...

I'm no expert (never having owned a turbo'd car), but I didn't realise that was the case. I would have thought all BOVs help to prevent stalling the turbo and hence prolong its life.

I'm pointing this out just in case the OP has got the wrong end of the stick (it sounds like he's considering removing the BOV completely, stock or not), but I've probably succeeded only in confusing things even more.

Isn't it the case that the stock recirc gets overwhelmed when the boost is increased? So a larger aftermarket BOV is required to stop stalling the turbos if you're running hybrids or a single?

Ah the joys of a Jap Spec car !

I'm no expert (never having owned a turbo'd car), but I didn't realise that was the case. I would have thought all BOVs help to prevent stalling the turbo and hence prolong its life.

 

I'm pointing this out just in case the OP has got the wrong end of the stick (it sounds like he's considering removing the BOV completely, stock or not), but I've probably succeeded only in confusing things even more.

The stock supra already has a "blow off valve" if thats what you want to call it. It's that round thing about 1inch across on top of the engine. It recircs the air back into the intake to reduce noise (Same as pretty much all turbo production cars), instead of to atmosphere (which causes the chirp sound)

The stock one is perfectly fine for use on bpu.

I'm no expert (never having owned a turbo'd car), but I didn't realise that was the case. I would have thought all BOVs help to prevent stalling the turbo and hence prolong its life

Homer means no additional benifit

Isn't it the case that the stock recirc gets overwhelmed when the boost is increased? So a larger aftermarket BOV is required to stop stalling the turbos if you're running hybrids or a single?

If the stock one does leak it's not because it can't handle it, it's because it'll be knackered.

It's a bit of an old myth this one, similar to the rising rate FPR's that were hawked on here a few years ago.

Is it still illegal to modify engine parts in france??

The stock supra already has a "blow off valve" if thats what you want to call it. It's that round thing about 1inch across on top of the engine. It recircs the air back into the intake to reduce noise (Same as pretty much all turbo production cars), instead of to atmosphere (which causes the chirp sound)

Ah, I see. My misunderstanfing. I'll move on now.

its fine on my uk spec car

not a fan of bus sounds but do like a nice little chatter or chirp like the bov on the Amuse supra >

not a fan of bus sounds but do like a nice little chatter or chirp like the bov on the Amuse supra >

thats not bov thats the stall sound homer was talking about. You cant/dont get it with the stock system i dont think

ahh fair enough, does sound perrty though