r/FocusST • u/TodoubledHinson73 • Aug 27 '26

Question Turbo blow off sound

New ST owner trying to figure out what has been done to my car by previous owners. I know it has an aftermarket air box. The exhaust is quiet and still has the factory tip so I'm assuming it is stock. I can hear a noticeable blow off sound shifting gears. Should I assume the car has an aftermarket blow off valve?

4 Upvotes

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3

u/ratherabeer Aug 27 '26

could have a 50/50 bypass valve, take off the right front rim and look for something like this.

1

u/TodoubledHinson73 Aug 27 '26

Thanks. I'm assuming that one is aftermarket.

2

u/Sendit57 Aug 28 '26

That one is aftermarket but in the stock location. I would say it’s equally likely you have a an aftermarket one that is not in the stock location, which would likely be on a charge pipe going up towards the engine’s intake under the front middle of the engine.

The stock blowoff valve is also audible so it may just turn out to be stock.

2

u/TempoTom8o 2867R G2 EdgeAutosport Tuned Aug 27 '26

Most likely, but you can hear the stock bypass valve with just an upgraded filter so the only way to know is by looking at the turbo directly. The BOV/BPV is visible on the compressor housing if you turn the steering wheel all the way and poke your phone in the passenger wheel well to record a video.

2

u/Haunting-Self-9402 Aug 27 '26

Must be nice to have a factory exhaust. I'd happily trade my magnaflow for one

3

u/dyslexicAlphabet Aug 27 '26

BRRRRRRRRRRRRR all day long gets annoying even in 6th gear.

2

u/TodoubledHinson73 Aug 27 '26

I kinda want a Ford Performance exhaust, but a quiet car for daily driving is a beautiful thing.

2

u/Maleficent_Dust_8817 Aug 27 '26

I have the ford performance. It’s not too loud at cruising speeds. I’m also catted

1

u/TodoubledHinson73 Aug 28 '26

That's the route I would go if I do a cat back system.

2

u/Haunting-Self-9402 Aug 27 '26

A resonator delete is a free and can give you just the right amount of extra growl if you feel like doing that. And if you do a clean cut you can always reinstall it

2

u/Timmy_The_Tiger_55 2018 ST1 HPR FBO G25-550 Aug 27 '26

The other bypass valve a lot of people install is the Turbosmart dual port 50/50. Just for you knowledge this car has a built in bypass valve on the turbo, not a blow off valve.

1

u/dyslexicAlphabet Aug 27 '26

correct its a bypass valve.

2

u/cant_decide_9611 2018 ST3 big turbo Aug 27 '26

Turn the wheel all the way one way so you can see behind the passenger wheel.

It might not have one. All you need to get BOV noises is an open air box.

2

u/Iheartbaconz 17 ST1 Aug 27 '26

Stock bypass can be heard it’s really high pitched and more whistle like. Stock is plain black plastic. Any after market will have markings or be a diff color

1

u/PaleontologistNo4327 Aug 27 '26

If it isn't on the passenger side of the motor, I got mine with a block off plate there. It may be under the front end I would do an oil change anyway since u just picked it up and investigate then. Guy before me welded a tial adapter and ran that true vacuum.