TOYOROTOR

iTrader: (1)

looking for a pretty cheap but good bov to use on a system boosting only 10 psi...

coldy13

I got a cheap *** one off ebay, it was $50. The company was Tyfoon Motorsports. It's actually a good BOV, works great on mine and worked good on my friends TII until his dumbass blew it up

680RWHP12A

none, its not nessisary... i just saved you $$$!!

comradegiant

Just stick with the wastegate. BOVs aren't really necessary, even with high boost cars.

93BlackFD

stock FD BOV

Anex 570

You have no idea how long I've been thinking why it needs it. After working on big tractors with deisel turbo, I relized how simply they are, they dont even use waste gates. I was however thinking how a BOV would make it better on it though, if you have a wastegate anyway? ..

FD_dave

stupid question, but do FD's come w/ BOV's stock from factory?

REVHED

Most diesels don't have throttle plates hence no need for a BOV.

FB II

dont use one. i'm not. when you have money you can afford to blow, then get one if you really think it's neccassary.


edit: wastegate flutter sound SO ******* AMAZING! better than any bov i've ever heard.

gmaz

I would think BOV are important because they release the boosted air when you shut the throttle plates! if you don't have one the air goes back to the compressor turbine and phyically stops it! that is the fluttering you here, (compressor surge)ie.. you need a BOV. This can also harm your turbo.

comradegiant

Wastegates release boosted air just as well as BOVs. There are an awful lot of old-school monsters that run just dandy without a BOV, case in point: TT Grand Nationals.

FB II

completely un-true

GavinJuice

Diesels don't have throttle plates at ALL, they don't have vacuum. You operate the fuel pump with your foot, not the non existant throttle plates.

FB II

i have a brand new never used still in box HKS super sequential bov w/ mounting flange. anybody want it? i dont think i'm going to install it now. not sure tho, we'll see. hahaha

TOYOROTOR

iTrader: (1)

" if you don't have one the air goes back to the compressor turbine and phyically stops it! that is the fluttering you here, (compressor surge)ie.. you need a BOV. This can also harm your turbo."

i heard the same thing..... cuts the turbos life in half.
now need to know if thats true or false????

Aaron Cake

iTrader: (1)

I'm not sure you know what a wastegate is vs. a blowoff valve.

A wastegate is used to control EXHAUST flow to the turbine. It bypasses exhaust past the turbine and straight into the exhaust system. The more exhaust bypass, the less there is to drive the turbine and thus the turbo makes less boost.

A blowoff valve (or bypass valve) is on the INTAKE side, after the compressor but before the throttle plates. When the throttles snap shut, it's job is to vent excess compressed air either into the atmosphere or back into the intake track before the turbo. This prevents the pressure wave from reflecting off the closed throttle and going back into the turbo (thus smashing into the spinning compressor). Also prevents the compressor of the turbo from stalling. "Stall" is when the compressor has compressed the air as much as it can. Instead of working, it basically spins freely and quickly overspeeds itself.

A BOV and a wastegate are two different devices for two different reasons.

Rotortuner

Cake knows what he is talking about, And for almost all the rest of you that think you dont need a BOV, then why do highly engineered cars that come from the factory stock with turbos nearly ALL have BOV's they are very small usually just cheap little valves, but none the less they are there. I have a friend that blew his compressor wheel because he didnt use a BOV. When a BOV is not used the deflected pressured wave that hits the compressor severely shortens life of the turbo. Please note however that most BOV's such as those on FD's are good to about 400 horse.
Also some of you mabe getting BOV's confused with pop off valves, a pop off valve releases excess boost on the intake side befor the throttle plates, its basically a ghetto way to compensate for not having a large enough waste gate. If your running fuel injection, its not accounting for the lost air through the pop off valve and runs rich. The pop off valve opens at a set pressure, so if you set it at 16psi it will open and relieve at 16psi and not let the engine see more.

CJG

Junia

BOV is a good to have but its not a necessity

elwood

iTrader: (1)

I don't see how the pop off valve is different from a BOV. Everything you've said about a pop off valve is the same as for a BOV, except for the boost level it's set to operate at. A BOV is typically set to operate at a pressure above that which the wastegate is set at.

Also, a benefit of a BOV is that it keeps the turbo spinning at a higher RPM after you've closed the trottle, so when you jump back on the throttle, the turbo will spool quicker.

FB II

okay, if you dont use a bov, you get a "flutter" noise (which is nice sounding imho). yes it's coming out where the intake filter is. lots of people (the majority) that buy these modern turbo cars do not want to hear their car making rediculous noises every time they shift. all that stock bypass valve is for, is to get rid of that noise. you can read your mazda manuals that come with the cars. the msp's have it as well, it specifically states, that the bypass relief valve is there to prevent unwanted noise. it will not say anything about affecting how your car runs. because it won't make a difference. there have been many tests to show that cars will boost just as quickly between gears regardless of bov or not. about turbo's breaking because of this? i think it's rediculous. air doesn't have a severe weight, that flutter is just from the surging air getting "chopped". if it was STOPPING the compressor, you would hear nothing and the damn car would probably buck like a ****. i dunno, if you like the noise; go for it. that's what i say. i'm just a fat kid in a 1st gen.

seanrot

iTrader: (2)

The BOV is controlled by a line off the intake manifold that will release any pressure inside the intake piping. Saying that if you dont reach your full boost the BOV will still release the pressure. where as the pop off valve will only release boost if it reaches its preset release point.

As for my car I have both a pop off and a BOV. both to serve different aspects. BOV releasec the pressure after the throttle closes and the pop off is incase of a boost spike It will blow it off and leave me with a rich mixture instead of a lean.

I have mainly dealt with the HKS BOVs and have ran about 16lbs without it leaking. My personal favorite is the old school HKS BOV, nice sound

FB II

see that is a smart setup. for all out safety, copy what he has done. nice job!

Junia

I don't like them on my car because I'm used to having them leak on me when I used to run them on my other car.

S2-13BT

I've done plenty of street driving and 4 open days at my local track with no BOV. Boosting upto 14psi with a standard S5 turbo. I have had no problems and my turbo still spins great. No shaft play and it's all good.

Read this: click here.

I think someone mentioned this above but anyway. Factory cars have BOVs to stop the flutter noise. Can you imagine the average punter dropping into mazda to test drive an FD. He shifts the first time and gets surge, wonders about it, shifts into 3rd and starts to think things are wierd, shifts into 4th and starts to question the dealer about the strange noise. Let's face it, you have to be an enthusiast to like it.

IMO it comes down to personal preference. If you wanna throw away some cash and get that woosh noise then have at it. Otherwise spend the money on something that'll actually improve your car.

Rotortuner

You guys do what you want, half of you dont even have turbos any ways. I will continue to use my BOV not only because it sounds cool and is very addictive but beacuse i know it cant hurt my turbo, it will only help it by not allowing the compressor wheel and center bearings to see a sudden increases in stress due to th pressure waves hitting it when the throttle is let off. Think about the torsional shear stress that is devoloped on the shaft as the exhaust gasses continue to rotate one end of the shaft and then you suddently try and slow the other end, it is a slight twisting force, couple moment. This may not cause immediete damage or failure, but could reduce life. especially in a mechancial device where tolernces are so tight and spins at very high rpm. I expect my turbo to last about 100-120 thousand miles. I hope a couple of you run without them and we can see you replacing a turbo at about 70k or so because of compressor wheel or center bearing failure.

CJG