Blowoff Valves

I like the sound of the WRC ones

>>15607791
Is it functional or is it just a whistle to make the noise louder?

Functional BOVs are great, noise-adders (like the one from Boomba) are awful.

>>15607848
What seperates a functional from a non-functional one? Just how much they vent to atmosphere? I know Boomba BOV adapters are 100% atmo and they're way too fucking obnoxious

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>>15607791

>>do you like them or do you find them douchebaggy?

I find mine annoying.

>>how much horsepower do you need before they become justifiable?

Horsepower is irreverent.

>>how loud is too loud?

Depends on how much you want people to notice the showoff valve. I use a recirculating one and its still kinda loud.

>>does the noise ever get old?

ZOMG yes. Pulling away from a stop at anything other than the lightest throttle input. Pssssssht!

>>15607818
wrc cars don't have any, in fact most really high performance don't.
it's more a street car thing.

>>15607873
To be honest, I'm not sure. I think Boomba is really a BPV adapter that adds sound, where as BOV are generally vaccuum operated and vent-to-atmosphere.

http://cp-e.com/webstore2/product/ford-fiesta-st-exhale-hks-bov-kit/

But I could be totally wrong about that.

Anecdotal evidence, but I've never used a blow off valve on any of my cars and I've never had a busted turbo. The best BOV is no BOV. If you run a closed system, it'll knock 10 or 20 thousand km's off the life of a turbo, so largely insignificant.

Blow off valves are pure rice shit. Either use a proper bypass valve or none at all imo.

>>15607897
Whats that thing that kinda flutters like its blowing off? I'd link a video but im on mobile

>>15607923
Antilag.

>>15607880
>horsepower is irrelevant (ftfy)

Well if you put a BOV in a slow car that is making under 200hp, it's kind of like ricing your car to look like an F&F dragster even though it's completely stock under the hood and is under 200hp. You're just asking other cars on the road to embarass you.

>>15607923
compressor surge and wastegate flutter

>>15607938
not this

>>15607938
Another trip to filter under "fucking idiot ignore forever"

>>15607944
Not too many turbo cars under 200hp, unless they're diesel.

>>15607952
>>15607958
You don't even hear the wastegate on modern rally cars.

>>15607966
please explain how that means anti-lag makes chirping noises

>>15607923
WRC cars with antilag keep the turbo spooled off throttle, the chirping they make is the turbo huffing air against the closed throttle body while off throttle, and then having that pressure wave come back through the turbo. Each wave is just as loud as the turbo stays spooled from the anti lag.

On a street car the first pressure wave is the loudest, and then they peter out. How long/spaced out the chuffs are is determined by intercooler size, piping diameter, and length, as well as how big the turbo is.

>>15607979
You mean how it's the antilag system doing that whole chirping noise? lol
The antilag keeps the turbo spooled, the flutteringnyou hear is essentially air pressure generated by the turbo that has nowhere to go.

You can hear it perfectly in this
https://youtu.be/2tP7T0g0zA8?t=47

They sound cool on big, laggy turbos, and are really fucking annoying on tiny turbos that spool up in a microsecond. An Evo will only vent when you want it to, but a lot of modern cars will just constantly PSH PSH PSH PSH PSSSSHHH no matter what.

>>15608016
it wouldn't be making that chirping noise if there was a bov you utter twat.

stop moving the goalposts because you were wrong

>>15608079
Are you genuinely retarded?
Who the fuck said rally cars had bovs?

Chirping noise = antilag
Flutter noise = literally air pressure generated by the turbo that has nowhere to go if the throttle is shut

>>15607944
Saw a new ecoboost mustang and heard it blowing off a lot, not sure if they all do, it sounded aftermarket to me. T b h it sounded too artificial

>>15608092
>Chirping noise = antilag
yeah nah. just stfu

>>15607923

EH MISSUFIRINGU SISTEMMU

>>15608092

Anti lag sounds like a machine gun going off. Extra unburnt fuel dumped down the exhaust via retarding the engines timing.The explosions down the exhaust help keep the turbo spooling. The other noises you're hearing when the rally car hits the jumps is the engine bouncing off the rev limiter.

- Chirping noises are usually when a turbo car is not running a BOV and has the valve blocked off. It's air that's meant to be dumped to atmos going back against the turbo causing flutter.

-

>>15608124
>>15608150
I think what he's saying is that the chirping noise is a byproduct of the antilag, like I did in >>15607981.

>>15608167
yeah, it's called damage control

https://www.youtube.com/watch?v=_K0LFadOKBc

>>15608150
I know antilag sounds like a machine gun. I was just saying that chirping noise was the result of antilag.

>>15608167
Exactly...
It's literally pressurised air being bounced off.
Some of it is the wastegate venting, but it's not THAT loud.


>>15608195
Nah, you just can't read.

>>15608195

You're fucking retarded m8

>>15607880
>ZOMG yes. Pulling away from a stop at anything other than the lightest throttle input. Pssssssht!

just add more washers/tighten the spring.

>>15608197
>I was just saying that chirping noise was the result of antilag.
what about when it isn't?

>>15607880
>zomg


Please hang yourself as soon as possible.

>>15608197
> tripfag
> incharge of being wrong
Just another day on the Mongolian Yert spinning board

>>15608209
It is. The antilag keeps the turbo spooled.
The spooling turbo keeps delivering pressurised air that is bounced off (chirping noise) and eventually the wastegate dumps the excess pressure (to prevent damage while regulating maximum pressure) so you get an additional "ssssss" noise or a light chirping noise.

>>15608197
>I was just saying that chirping noise was the result of antilag.
why not just say it's the result of being an internal combustion engine, or the listener not being deaf, or some other shit reason if you want to be retarded?

>>15608227
>you can only get sick flutters if you have anti lag
go crash your punto you silly fuck

>>15608238
>as if we weren't talking about rally cars
Yeah, go put a watermelon-sized turbo on your civic and enjoy your sikk wastegate sound while having your boost pressure all over the place.

WRC cars only chirp if they have the anti lag turned on. If the driver flicks the antilag switch off, it'll tsu tsu tsu just like a regular street car.

The chirping sound they make is very similar to on throttle compressor surge, as the conditions are very similar (high boost, air unable to get into engine, starts forcing back through the turbo, yet turbo still spinning at full speed, causing compressor surge), which is really hard on turbos. At the end of every stage, the first thing the driver touches is the anti lag switch to turn it off.

>>15608254
https://www.youtube.com/watch?v=nCj6Spwl1CU&ab_channel=synaptic1

found a video

Tuning with a BOV will improve throttle response slightly. Adjusting the spring preload gets rid of a lot of annoying venting. I've got a GFB deceptor II with an adjustable ratio of vent/recirc... I have it venting above 11psi and seems to work well. Better than the factory by pass valve which get loose as old balls...

>>15607791
>Friend's Mini S has 187HP and a BoV
>My Volvo C30 T5 has 230HP and no BoV
CBTs a shit, I want the douche sounds

I have an intake and a diverter valve bypass for my tsutsutsutsu noise.

It's very subtle and is only audible at peak boost, so it's very sexy.

>>15607919

I disagree my stock bpv leaks under higher boost levels sometimes the best upgrade is to convert to a blow through system.

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theres so much misinformation in this thread it's mind numbing.

>>15607791
If you vent to atmosphere with a MAF based AFM you're officially retarded. No matter how much you're venting. Never vent to atmosphere if your car uses MAFs.

>>15608907
unless the maf is a blow-thru and placed after the bov.

retard.

>>15608920
Still dumb to vent to atmosphere. You can recirculate the extra air to keep the turbo spooled between shifts.

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>reading mjet's posts itt

>>15608762
Mine leaked too so I got rid of it and welded the bung shut.

>>15608786
"Wastegate chatter" got me good. Better not to correct them, it's more fun that way.

>>15609094
It's not as much air as you think.

There's also autos and guys that use NLTS

>>15609094
Very little air is reintroduced. And when you are making enough boost its better to not have to worry about surge.

>>15609117
It's enough to cause afterburn in the exhaust and excessively rich conditions if you slap one on a stock turbo car with no other work. It's also significant enough that EFR turbos are a thing.

NLTS is neat but you still want to maintain transient response even if you aren't shifting. If you get on boost, let off the throttle, then get back on the throttle an atmospheric venting BOV is going to have worse response than a properly tuned recirculating BOV.

>>15609153
If you're going nuts with boost and airflow you should be moving to speed density anyways. If you're using a MAF based system the point still stands that you want to use a recirculating BOV.

>>15609164
>It's enough to cause afterburn in the exhaust and excessively rich conditions if you slap one on a stock turbo car with no other work

wtf are you talking about

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>>15609164

> afterburn

Its called overrun friendo. And its not the cause. Moar fuel = cooler EGT's so you dont melt your turbo/manifold into slag.

I shoot flames out of my exhaust, MAP and MAF with a re-circulating valve.

>>15607880
>zomg

>>15607923
Compressor surge

https://www.youtube.com/watch?v=fq2ekzptguo&ab_channel=ToddLaurendet

tsu tu tu tu utut utu

>>15607791
Blow off valves are not needed, and are just for faggots. Do any race cars use them? No. Just another spot to get a boost leak.

>>15607966
Waste gate is not an interchangeable term with blow off valve...you're welcome

>>15609215
No, it's afterburn. Overrun refers to the coasting condition, afterburn is what happens when the rich exhaust meets outside air. It's called an afterburner in jet engines, not overrunner.

And shooting flames out of your exhaust is excessively rich. You should be targeting slightly rich mixtures for open loop but afterburn will damage your catalytic converter and exhaust.

>>15607791
i love my bov. ive had the car about a year and i still get on it just to hear it. i love the sound.

>>15607791
https://youtu.be/3pbUMXZvfi8

>zomg
>that pic

>>15608131
extremely underrated post

>>15609365
No shit.
You still almost don't notice the wastegate on modern rally cars.

>>15611920
Holy fucking shit I haven't laughed that hard all week.

OMFG tears

>>15607791
BOVs are okay. It's the ALS that's fucked up in a roadcar.

>>15609321
Doesn't have shit on the Audi IMSA GTO
https://www.youtube.com/watch?v=K7wrR42qcEg

>>15614531
tsuuuuuu tu tu

Is it possible to put a bov on 4 cyl diesel? I am thinking about ricing out my dads 2.0 tdi octavia

>>15614986
Nevermind, i found out why its impossible

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>>15609371
>You should be targeting slightly rich mixtures for open loop but afterburn will damage your catalytic converter and exhaust.

> damage your catalytic converter and exhaust

> catalytic converter

>>15615635
If you live in an area that traps smog like LA or San Francisco you're literally slowly choking yourself to death from NOx, CO, and VOCs.

Stop decatting your cars.

>>15615635
>damage your catalytic converter and exhaust
>> catalytic converter
Glorious fireballs of freedom

>>15615665
The amount of additional emissions from enthuisiasts the remove cats is magnanimously dwarfed by the hundreds of thousands or millions of catted polluting vehicles on the road.

>>15616906
That's hardly true when your fucking car is emitting well over 10x legal limits and you're living in an area where the local geography causes a smog trap to form. Especially when every fucking "enthusiast" thinks they've found some special secret in decatting for more power.

No drop in a flood feels responsible.