M-Flo

A BOV or some type of turbo bypass valve to regulate pressure is necessary, the silly whooshing sound isn't.

nd4spd_4_a_tc

srt4 does not come with a blow off valve, only has a bypass valve. Thats built onto the turbo. You can buy a mopar bov from dodge but it's ___.


The snap crackle and pops from a srt4 are 2 things, 1 the lack of a muffler and 2 it runs really rich. If you think a stock s0 srt4 is loud, go find a s2/s3 srt4.

I have a s2 with 3" turbo back no cat no muffler only 1 resonator. It's loud

I wish my tc could sound like that ;)

westsiderider

blowoff valve = bypass valve.

Conundrum_4000

By 'bypass valve' he means, it recirculates back into the intake and you really cant hear it outside of the car.. although with a CAI you sometimes can.. doesn't sound much like a BOV though.

Mopar makes a part that changes the stock recirulating bypass valve into a BOV though. ;)

ZPIracing

Well let me see if I can clear up some of the misconception.

A blow off valve, bypass valve, surge valve whatever you want to cal is not required on turbo cars. You can have a turbo charged car with out this componet. A bov does not regulate boost. A bov vents boost when the intake manifold has negative pressure. The purpose of this is so that the forced air does not flow back into the turbo housing. The biggest problem with bov is that they are spring loaded and if you run more boost than what the bov can hold it will release the pressure when the intake manifold is still under positive pressure thus creating a boost leak.

All new factory turbo cars that I have seen all have soem type of bov. Must factory superchrged cars also have one. The reason a bov is plumbed back into the intake track is do to maf readings. MAF adjust fuel according to the air it is sensing coming into the engine. Or on a turbo car pre turbo. When you vent all of this air out of the piping this creates a overly rich condition and usally leads to backfires, flames, etc.......all the cool stuff we all love about turbo cars!! Although it is cool it is not always the safest of situations.

On most new cars a lot more turbo/bov noise can be heard by simply geing an intake or removing the air resonator out of the intake track. I would suggest this befoe trying to vent a stock bov open atmosphere.

I hope this clears up some of the questions if you have anymore post up.

-Kenny

kshymkiw

First good reply i have read on this thread. With the correct technical information!

rotarycolt

This is very true, the rich conditions seen when using an atmospheric BOV are only present when on a hot-wire MAF vehicle when the pre-metered air is vented off into the atmosphere.

Not all factory vehicles came with bypass valves. Off the top of my head, I know that the GMC Typhoon and Syclone did not have one, nor did the Grand National.

Mx6GT91

Im sure the BOV that you heard was the Mopar BOV. They make a lot of noise even with a 1000rpms gas touch.
As said many times SRT-4's dont have mufflers. Its just a downpipe with factory cat and 2.5in downpipe back no mufflers.

SRT-4's sound like that because of the motor, not because of the exhaust piping. All cars are different and will sound different. The tC sounds like a mix between a 350z and a WRX. It has the tone of a 350 with the WRX rumble.

Adding to the list. Conquest/Starions did not have bypasses, I like the sound of no bypass. Wastegate flutter sounds great!!!!

kshymkiw

But you have to Wander if the Conquest/Starion was such a good design, so why did DSM choose to go with BOV's for the Eclipses/Talons.

StealthTC414

Your gonna say SRT4's dont have a blow off? Pop the hood, Go straight to the back of the motor, and Look down, Yes that little piece of aluminum is the stock BOV on an SRT4, Take an allen wrech and take the 3 bolts out and it will come off. Also pull the vac line off the side. U can take it apart and all it is, is a piece of rubber and a small spring. We replaced mine with the FORGED BOV,.Its a pain to get there but theres definetley a BOV on every turbo car whether its a recirculated BOV (ex 90-94 DSM'S) or a BOV that vents (SRT4)


Check www.turboneonstore.com for AM BOV's and Block off plates

Mx6GT91

From what Ive heard is that Eclipses/Talons have bigger/better flowing turbos and more stock boost. I dont really know. Maybe back then bypasses werent common??

Its not a blow off valve, its a bypass valve. There is a difference. Stock the SRT-4's vent back into the compressor because thats where its mounted. Not being a smart ___. There isnt a BOV on EVERY turbo car. Most bypasses vent back into the intake pipe.

ZPIracing

The big misunderstanding here is terminology BOV is simply another word for a bypass vale. They do the same thing, regardless of were they vent to. Open or closed loop they are still completing the same function. The aftermarket adapted the name BOV, were manufacturers still call them bypass valves. This is to “bypass” the air from returning to the turbo. We can call them “stop flutter valve” this does not change there function.

I am not trying to down play anyone, or create e-drama just trying to help everyone understand the forced induction process.

kshymkiw

[quote="Mx6GT91"]I think you might be correct. Because wasnt the Starion/Conquest a Turbo V6 running less boost than the Talon/Eclips which was a 4 Banger.

Mx6GT91

Starions/Conquests were 4cyl. They are the biggest 4cyl made still to this day. I think there 2.6L SOHC......Not sure of there stock boost though?? Grand Nationals were 3.8L

Eclipse/Talons are 2.0L's but they ran anywhere from 6-12psi stock.
My car runs 6psi stock but its got a small turbo, SOHC, 12valve, so all it needs is a small plastic bypass valve.

shuttlegoosecock

plain and simple those without a blow off valve are jealous of those with a blow off valve. they just sound amaznig.

TheQuietThings

BOV = sex

Joe_Dezod

The Mopar valve is what you probably heard. That thing is loud and vents at almost zero boost.

They mount the valve on the turbo housing itself. This is the worst spot to do it, but hey it works. Putting the BOV as close to the TB is the best way to go. Air will vent out quicker and not have time to build a surge and head back for the turbo.

Older starions weren't the most expensive cars, and older technology didn't always have bovs. It's a bad way to go regardless of boost levels. 2psi will still spike and come back to the turbo, slowing it down and shortening the life of it. Bascally less performance (lag) and shorter life span. So all new cars come with some type of valve. VWs call them diverter valves. Same thing, as ZPI stated.

The Dodge SRTs get away with OEM installed atmospheric BOVs because they use MAP (Manifold Absolute Pressure) systems. MAPs only read the air pressure in the intake manifold and adjust fuel according to that. So if the TB closes, the BOV can vent as much air as it wants without creating a rich condition, because the MAP is adjust fuel for what air made it into the intake manifold, rather than what is entering the intake pipe (MAF - mass air flow).

I personally like MAPs better because of that reason. But still, Evos, STIs, tCs, about all toyotas and nissans, use MAFs. Hondas are the few to use a MAP system.

Some companies like AEM offer a MAP conversion system (3 Bar max which is good for over 30psi of accurate reading, also an upgrade available with the SRT through the dealer) to allow for easier tuning and for atmospheric venting.

I hope this ellaborated on what ZPI correctly stated. Between us and a couple other members I've seen on this thread, I'm sure we can answer about anything you guys need to know.

JasonH

Late model Porsche 944s and 968s had 3.0L four cylinder engines.

Mx6GT91

Have you heard wastegate flutter yet???
My car has the combo of both flutter and BOV.
I would take the sound of wastegate flutter over any BOV, too bad its hard on the turbo/bearings

Are you serious?!?! Ive never heard of that...........

tC-Collin

thats sick dude. im about to make a turn down