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FLUTTER sound as BOV

ATTN

By ATTN,
in Engines & Forced Induction

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KIL.08S Collaborator

KIL.08S

Posted
Posted

Ok, i just have to ask. My car as i bought it from japan was built extremely well... 2.3 stroker, 272 cams, 2535 turbo and so on. (i'm not trying to talk it up or anything i am just making a response easier) the workmanship is excellent and has obviously taken a lot of time.

the car DOES NOT have a blow off valve. i have kept it this way as it is a big defect me sign to any cop who wants to look under the bonnet. but is it doing my car as much harm as people say. the car has been running 1.2 bar boost for as long as i had it and had that dialed in from japan and i have not noticed any negative effects as of yet resulting from not having a blow off valve.

any help would be appreciated.

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aKTiVE Collaborator

aKTiVE

Posted
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i have also not run a bov on 3 of my cars.

I have covered 60,000 km in one of them, with no bov and running 18psi constantly and never had problems with the turbo.

so yeah there you go. It *may* be bad, but how do you tell how much wear and tear it takes out on the turbo if any? I havent had one of my turbos opened up and my turbo builder say "SEE THIS HERE< THIS IS WHERE THE FLUTTER BLEW YOUR TURBO"

I've never blown a turbo *touch wood* but they are a part of the car that gets worn over time and needs replacing.

HKS34R Collaborator

HKS34R

Posted
Posted
Ok, i just have to ask. My car as i bought it from japan was built extremely well... 2.3 stroker, 272 cams, 2535 turbo and so on. (i'm not trying to talk it up or anything i am just making a response easier) the workmanship is excellent and has obviously taken a lot of time.

the car DOES NOT have a blow off valve. i have kept it this way as it is a big defect me sign to any cop who wants to look under the bonnet. but is it doing my car as much harm as people say. the car has been running 1.2 bar boost for as long as i had it and had that dialed in from japan and i have not noticed any negative effects as of yet resulting from not having a blow off valve.

any help would be appreciated.

Do you get any compressor surge?? My understanding is that this would be the only threat to your engine from having no BOV, hence, if there's no compressor surge (i.e fluttering), then there would be no problems??

JCMarshall_Law Proficient

JCMarshall_Law

Posted
Posted

Notice that I have not said that it will damage your turbo just that having no BOV will cause the compressor to operate way out of its efficiency range during gear changes,

which is not a good thing

The main reason I have not said that damage will occur is because like aktive said, I could not give any example of a turbo that failed due to flutter. Still everything I said was true.

Although I can give a reason why flutter could cause damage. This is just a theory and will remain so untill proven / disproven.

As already said flutter is caused by the compressor operating out of its efficiency range, ie: the flow is far too low for the blades to be operating efficiently. A similar thing to cativation in liquid pumps occurs, at such low flow (throttle virtually closed) and with the turbine still spinning upwards of 20000rpm, the fluid (air) is stalling over the blades. You can hear a similar thing when a helicopter makes a hard turn or a sudden stop, a loud chopping sound, (much louder than the engine or normal blade noise). Anyway, this stalling over the blades will result in high frequency loads being applied to the turbine blades and the blades will vibrate. It is fairly obvious that that would be a bad thing, causing bearing wear and accelerating cracking of the turbine.

So there is one idea, feedback welcome.

If you drive your car like a racing car all the time it would prob be an advantage not having a BOV, ie keeping the pressure in the intake during gear changes, the turbo would not have to do the work to repressurise the system when the gear is re-engaged, and the short shift time would not allow sufficient time for the turbine to spool down.

In the end, the engineers who designed this stuff are very intelegent people, so I usually think before dicking with things "why did they do it that way".

Plenty of people like the sound, so if you think you know what your doing, go for it.

Guest Mashrock

Guest Mashrock

Posted
Posted
how do i get the Flutter sound on my s2 gtst?

i was at a wrecker and this guy came down changing gears letting off this cool flutter sound into the atmosphere  

i asked the guy how he did it but he did go into much detail i guess he want to keep it a secert

he briefly said that he blocked off the BOV and he asked if i had a aftermarket air filter, he said thats all i needed to get that sound

i really wanted the flutter sound because it sounded MAD  

i want to know if anyone knew how to do this?

i gets a good flutter noise with my gti-r on a standard bov..

through an apexi pod..

i just back off ever so slightly when on boost. but maybe you'll have to work it out a bit..

??

Fly_With_Sky Rising Star

Fly_With_Sky

Posted
Posted
Just be aware of the consequences below:

1) Get canary (defect sticker) easy as

2) Blow turbo

3) Very careful with this one, YOU MIGHT BE UP FOR A NEW BOTTOM END (been there done that)

The sound is wicked, but there are to many 'againsts' to have it on ya car. just get a after market BOV.

ok i am aware of how the first two can occur but could you please explain how compressor surge can make you need to rebuild the bottom end?

R32_GODZILLA Proficient

R32_GODZILLA

Posted
Posted

Ok, lets say you were running 1 Bar of boost. When air is compressed and travelling through the intercooler and then through the trottle body into the engine, what air pressure would be lost before it gets into the engine? Probably a differece if you either use a bar-and-plate or tube-and-fin intercooler, am i right? Then as you get your foot off the accelerator and the throttle shuts, the air is forced backward towards the compressor, again loosing pressure when having to travel back again through the intercooler and back to the compressor wheel......

Now if you know the end result of pressure effecting the comressor wheel, wouldnt that be the factor of how much damage could be done to the wheel, bearings, etc?

Does this make sense?...lol (correct me if i am wrong)

Just my 2 cents.

Steve.

  • 4 weeks later...
geno8r Grand Master

geno8r

Posted
Posted
well i got the fluttering noise on my car, its pretty sick, especially if you run full boost, thaz when its loud of its head.

When u do the "cooler noise" i call it, in front of ppl, every cnt looks at you mate. Its like you are a celebrity mate. but you gotta be carefull, read reasons below:

1) Attracts chix

Is this guy serious? Next time im out in town on the tune meeting new ladies I'll now first introduce myself then proceed by saying "I have a fluttering BOV on my car" & then i just assume the reaction will be 'owww wow your so brave' & then she'll have s3x with me because im so cool & she’ll think im a celebrity :(

doridori32 Rising Star

doridori32

Posted
Posted
Ok, lets say you were running 1 Bar of boost. When air is compressed and travelling through the intercooler and then through the trottle body into the engine, what air pressure would be lost before it gets into the engine? Probably a differece if you either use a bar-and-plate or tube-and-fin intercooler, am i right? Then as you get your foot off the accelerator and the throttle shuts, the air is forced backward towards the compressor, again loosing pressure when having to travel back again through the intercooler and back to the compressor wheel......

Now if you know the end result of pressure effecting the comressor wheel, wouldnt that be the factor of how much damage could be done to the wheel, bearings, etc?  

Does this make sense?...lol (correct me if i am wrong)

Just my 2 cents.

Steve.

Steve ... nashio..

that air doesnt DAMAGE the compressor wheel or bearings.

The air is so light it doesnt effect the turbo. 90% of race cars or serious street cars dont use BOV's.

They are a market strategy.. did you know NOT ONE PERSON IN THE WORLD HAS SHOWN PROOF ON DATALOGS THEY WORK!!! Where as people shown they dont do anything.

My street car uses a T04S 1.00a/r and it runs always around 22+psi and the turbo has been on it for over 60,000klms.

I push the car to its limits and take it to the track/drag races all the time.

When is the next meet after the upcoming one ? car will be going to next event!

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