fortyoz2eric

this is one thing i've always wondered but nobody could give me an answer - can't they make a blow off valve that doesn't whistle when it goes off? after riding in my friends GTI 1.8t i always thought that i'd get sick of that sound realy fast (i'd be reving the car nonstop) and i'm not sure why they whistle in the first place...anybody?

AreExSeven

I don't think its the BOV whistling. The BOV makes a popping noise. Its probly the wastegate you are hearing?

Greg

the manufactures install wind breakers (little slices of metal) to cut up the airflow making that noise. HKS ss and Greddy type S both have the whistle. A normal bov (greddy Type R) jusy makes a nice psssssssfffttt noise when it blows off.

F=ma

Nah the wastegate makes a noise once you hit any appreciable amount of boost, which is probably 4000 rpm and past. Its not a whistling noise persay, its a bit more harsh and unpleasant of you ask me. Its more pronounced if you're dumping straight into the atmosphere instead of back into the catback. But that kills emissions.

BOV's have a more whooshing/sneezing kind of sound than a pop.

fortyoz2eric

oh, well my friend does have the HKS bov, so that does check out. granted i haven't been around many turbo cars but i think every one i've heard seems to be extremely noisy/whistley - i need to hear a whooshy/sneezy one

peejay

Get a copy of "Getaway in Stockholm 2" - the video footage is all taken from the nose of an Escort Cosworth. Best sounding BOV I have ever heard - it doesn't whistle or sneeze or anything, it just vents air.

F=ma

Watch this video. (Or listen to it rather)

T51R Supra with Twin BOV's... Greddy Type S I think but I'm not positive.

http://www.racingflix.com/downloadvideo.asp?v=96

Greg

.

RX7withNitrous

yeah the one in that video sounds like a greddy type-s best sound ever.

Turbo II FC

iTrader: (14)

Personally I really like the Blitz Super Sound Dual Drive bov. I think it has a very nice sound to it. Pretty much sounds like a bunch of air being pushed out.

Greg

My fav is the greddy type r

$150FC

dood that supra shifts mad kwik, yo

Honestly, though, I haven't decided if I like the whistling noise or the psssht noise more. Maybe two BOVs, one of each variety? Heh.

edit: i could have sworn i put that smiley in there the first time

fortyoz2eric

that supra is friggin awesome - yea i'd definetley go whooshy-sneezy. so heres another thing: does the FD only have one BOV? and if so is this because its sequential?

fastrotaries

it's the sudden rush of air that causes a disturbance. I really don't remember all that much about harmonics, but i know that you'll always have sound. no matter how minimal. the quitest system(s) are those that don't vent to the atmosphere.

fastrotaries

i've been trying to fit a Kazoo in A minor, so i get a sadder tone to the shift.

jspecracer7

Me too.

91fct2

iTrader: (1)

many of the companies that make blow off valves are designing them to sound that way on purpose you know to appeal to the "fast and the furious"wannabes
and some blow off valves have to be tuned so that they dont open to early or not early enough(depends on the amount of boost you are running) a poorly tuned blow off valve can sometimes cause the whistling sound the apexi twin chamber bov sounds great no whistle what so ever i have one on my 91t2

Stepdaddy

correct me if im wrong but dosnt the sound depends on the psi and i mean a 4 banger compaed to a 8, wouldnt the sound differ?

Stepdaddy

91fct2

iTrader: (1)

why would the number of cylinders make a differance in the amount of boost you run psi is psi no matter how you look at it