The Driver

iTrader: (4)

I went single turbo and I really don't want to hear that annoying squeak, If I do then what is the quietest on the market? I'm pluming the WG into the downpipe so I hear one less thing. Anyways do I need one, no wise *** answers just a straight yes or no and maybe a "as to why I don't or do"?

rossc

Yes, to prevent pressure surge from decreasing the life of your turbo.

There is a near noiseless solution though. Instead of a blow-off valve, use a bypass valve and route the exhausted pressure back into a pre-turbo intake pipe.

Mahjik

iTrader: (1)

"Need"? No. Good idea to have one? Yes. You can always plum the release back into your intake to suppress the noise.

The Driver

iTrader: (4)

Sounds good to me...

Dudemaaanownsanrx7

iTrader: (23)

yes you should def have one, it prevents compressor surge which can damage the turbo, and allows the turbo to keep spinning when you shift so the boost comes back on quickly. You could always run an air box similar to the stock design and vent it back into the box.

The Driver

iTrader: (4)

Yea' I'm going to do a custom piped intake (cold air with piping or ducts and recirc it back into the system.

rossc

Where do you draw the line at "Need"?

Do you "Need" to run an air filter on your intake? Well no, you don't. But then why do 99.9% of cars in existance come with some sort of intake filter? Because it promotes engine longevity.

Do you "Need" to run at least 91 octane in an rx7? Nope, you can run 87 just fine. But again, nobody does. Do you "Need" a boost control mechanism? Well no, you could leave the wastegate closed and just pedel the throttle.

Do I "Need" to get out of bed and haul my *** to work Monday-Friday? No way man, I could sleep the day away. But its impractical.

So do you need some type of pressure relief on a turbo system? Yes, you need one. Why? Well simply because it would be pretty retarded not to.

Azcamel

iTrader: (1)

you can run dual wastegates

Mahjik

iTrader: (1)

Many people don't run BOV's. Most turbo-charged race cars don't run them as they can be a point of failure during a race. Granted, race cars aren't necessarily looking for longevity out of their turbos, but there are many people on this forum who do not use them. They have been doing it for years and their turbos have not failed (some single turbos, some on stock twins).

Mahjik

iTrader: (1)

One of the many threads with some good information:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/about-eliminating-stock-bov-495277/

BigWillieStyles

on fdowners.com, an aussie forum, most members seem to be not running a BOV so its arguable whether you need one.

FD3Smaniac

iTrader: (3)

synchronic BOV not that much sound.

dhays

iTrader: (1)

That is only because their cars are upside down and backwards.

JHew84

iTrader: (9)

Actually you're wrong. Garrett designed all of their BB turbochargers with the specific intention of withstanding massive amounts of compressor surge due to being run on a BOVless system. There was a huge discussion on this topic over at NASIOC awhile back and quite a few people surfaced who had been running no BOV for ~100K miles without any ill effects on the turbo itself. The conclusions quite a few of them came to were that by the time the turbo itself was damaged from compressor surge it would have already failed from something else anyway, and that running a BOV really wouldn't prolong the life of the turbo to such an extent that it was at all necessary to use one.

Just because it is accepted as the norm certainly does NOT mean it is the rule.

If you so choose to run a BOV and don't want the noise then getting one that recircs would be your best option. Although I must say you're nuts for not wanting that beautiful pressure release! .

rossc

100k+? That seems unlikely. Who even remembers that far back? My friend recently told me she ran into Kanye West at the mall and he asked her to go back to his hotel with him. I told her this was unlikely.

Answer me this. If re-circ valves are so useless, then why are they still being put on brand new forced induction vehicles? If motor companies can save $1 on the production of a vehicle, then they would do so in a heart-beat. The material costs for these valves arn't free, and the engineering certainly isn't free either.

Bottom line, if I can get even an extra 10k out of my $4k turbo system because I spent $50 putting in a stupid re-circ valve, then you can sure bet I'll spend the $50.

And if the man wants his rx7 to be quiet, then going without a re-circ is NOT the way to go. Have you ever heard compressor surge at 1bar? That sound would annoy the crap out of me way more than the sound of a BOV would. The re-circ valve is the quietest solution by far.

So yes, you do need a BOV/re-circ. Unless as suggested you plan on racing for the cup. Then you might have some type of BOV related catastrophic failure costing you the fame, fortune, and women.

TurboMazdaSpeed

get a tial 52mm bov, they literally are silent and they vent into the atmosphere so you dont have to go through the hassle of plumbing it back into your intake..

hsitko

iTrader: (1)

Firstly. This has all been covered already in this thread. The reason that new forced induction vehicles come with diverter/recirculation valves is because the turbos in almost all factory turbo applications are standard bearing. Supposedly garrett made their ball bearing turbos capable of standing up to no bov. Not to mention that these companies have to make sure they are not replacing turbos under waranty.

Seccondly you are right, compressor surge is pretty loud, and typically longer in duration than a vent of pressure from a bov.

Thirdly. If a bov fails, what happens? Nothing catastrophic for a race thats what. You then get compressor surge. Which is the same thing that happens when you run without one. I have been under the impression that the reason not to run one is because you dont vent off all of your boost. That would mean it would take less time for a turbo to respond between an off throttle to on throttle situation. Sacrificing turbo life for turbo response.

rossc

I realize that it already has been covered that garrett has a ball bearing system capable of standing up to compressor surge. The big idea is how many people actually have a garrett turbo? I was simply advocating that people were defending the use of no BOV systems for all types of turbos. Given the pros and cons, it's pretty silly not to run a pressure relief.

You are totally wrong about your statement that running no BOV will help maintain boost between shifts. Those pressure waves are slamming in the REVERSE direction the compressor is supposed to be pushing air, slowing down the rotation, and making spool up longer. Running a pressure relief gives you performance benefits and logevity benefits, for the 50th time I say it is pretty silly not to run a pressure relief.

And since you didn't pick up on it, I was being sarcastic about a BOV failure being catastrophic.

Dudemaaanownsanrx7

iTrader: (23)

a have a tial 50 mm BOV and its not silent, whats different w/ the 52 mm besides being 2 mm larger?

This is an interesting discussion, both sides seem to have valid points. Personally it seems running at least an aftermarket BOV would have improved boost response between shifts, but at least a couple swear by improved performance not running BOVs. Maybe more people can try it and report back. I'll try it when i start running boost again... i'm guessing just unhooking the vacuum line to the BOV should do the trick yes?

It also seems if the compressor wheel does indeed spin the reverse direction from not running a BOV that it would restrict the exhaust as well as cause slower spool between shifts. Though maybe what happens is different then this.

rossc

That makes me revisit the thought of how a BOV can cause race failure. If you simply unhook the vacuum line, you are going to get fairly severe boost leak at high psi since there is no back pressure on the BOV piston from the vacuum line. Any failure on the vacuum side of the BOV would cause this.

If you wanted to test the difference, you would have to either remove the the BOV completely or add a check valve in the vacuum line to hold max pressure at all time.

mdpalmer

iTrader: (24)

rrrrraahhh........ pppssth.

rrrrrrrrrrraaaaaaaaahhhhhhhhhh.................. pppsssth.

Yeah, I think you need one But look out, people may start calling you a ricer. See defn. 51

http://www.urbandictionary.com/defin...=714876&page=8

sickboy2345

have you guys got a picture of stock blov off valve on the stock engine? i dont know where it is or how it looks like and i remember someone saying after i posted a pic of my engine that my blov off valve is disconnected...have you got [pics so i can see what its connected to...

cheers

MrNizzles

iTrader: (5)

**** the fame and fortune, I will take the women though! Why can't the last 3 losers get some?!

Hitokiri_Gensai

iTrader: (2)

Syncronic's BOV is nearly silent. Its a good alternative to most Greddy and HKS units and stuff.

Personally, i believe compressor surge does shorten the length of the turbo, how much? i dont know. but id rather be safe than sorry.

like a lot of people pointed out, professional teams dont use them but then they're not worried about a 1500 dollar cost whenever a turbo goes.

Dudemaaanownsanrx7

iTrader: (23)

yeah i was thinking the same thing after i wrote that, that you might need a check valve to keep the pressure on the BOV.

This may not be an issue at lower boost levels though.

I can see how a BOV is one more thing that could go wrong, i dont think engine failure could really be an issue if it failed, but you could lose some power. In operation its not much different then a wastegate and thats definitely more critical to engine life. If a person has a quality BOV there isnt a whole lot that could go wrong with it.

You could also powershift with or without a BOV and then you won't lose any boost between shifts, but this is harder on your drivline.