Boost surge / flutter ?

Jonesy

Jonesy

Member
I've had this problem for a little while now but just learnt to live with it. Basically after accelerating and reaching full boost, depending on the speed that i let the throttle back off some times the boost flutters (hard to explain). If i let it off quickly or really slowly theres no problem, but if i let it off at a sort of medium pace this fluttering / surge occurs.
Doing a search through previous posts it sounds like it could be surge, what would cause this ? the way that my bov is plumbed in ?
Cheers
 
R

rx jamie

New Member
just means there is not enough vacuum to open your bov, so the air surges over your compressor blades making the fluttering noise. or you may have an adjustable bov and its adjusted very hard.

or

the bov may operate but not a high noise level because of the low boost pressure contained in the piping, ( light throttle) so therefor you will here the surge rather than the bov wooooossh.

you will always get some degree of surge but a bov is there to limit it. when you snap the throttle shut on full boost the air races out the bov with a loud hiss or woosh therefor you probably wont here the surge.

just my thoughts on it anyway.
 
Jonesy

Jonesy

Member
It's not really the noise that im bothered about, you can actually feel the car sort of jerking as the boost level is fluttering about, feels a bit harsh, worried about damaging the turbo ?
Cheers for your input
 
antgtir

antgtir

New Member
What kind of BOV have you?

How have you installed it?

Best thing is to post a few pics of it installed and / or compare them to others install.

Try adjusting the BOV so its on its slackest rating see what that does if anything.

Ant.
 
R

rx jamie

New Member
your turbo should be fine imo. my car does this also at motorway speeds when cruising on light throttle.and as youngy has said, my drivers side engine mount has gone.

some people run withbovs fully tightened down, or even without, so they only get surge. dont wrry about it. just enjoy the noise
 
gtirx2

gtirx2

Member
I get this also, and have been told it is when you hear the flutter its the air coming back though the turbo the wrong way and sometimes it makes it as far as the maf and interfears with it causing the car to jerk about a little bit.
 
Y

youngsyp

New Member
gtirx2 said:
I get this also, and have been told it is when you hear the flutter its the air coming back though the turbo the wrong way and sometimes it makes it as far as the maf and interfears with it causing the car to jerk about a little bit.
Click to expand...
That's interesting mate and seems more than possible, if you're making enough boost.
 
stevepudney

stevepudney

GTiROC CHAIRMAN
Staff member
Jonesy said:
I've had this problem for a little while now but just learnt to live with it. Basically after accelerating and reaching full boost, depending on the speed that i let the throttle back off some times the boost flutters (hard to explain). If i let it off quickly or really slowly theres no problem, but if i let it off at a sort of medium pace this fluttering / surge occurs.
Doing a search through previous posts it sounds like it could be surge, what would cause this ? the way that my bov is plumbed in ?
Cheers
Click to expand...
I don't think you'll find it's anything to do with the bov (what bov have you got ?) it sounds like turbo surge to me, basically your internal wastegate can't flow enough air.

gtirx2 said:
I get this also, and have been told it is when you hear the flutter its the air coming back though the turbo the wrong way and sometimes it makes it as far as the maf and interfears with it causing the car to jerk about a little bit.
Click to expand...
I assume the flutter your talking about doesn't happen on boost, the flutter off boost is more than likely air coming back out, "reversion" this can happen if your inlet is to sort and your MAF is to close to the comp inlet. My Z32 was attached to a 3" 70 degree pipe which was only about 12" long, I used to get reversion when I pulled up to stop, the revs would dip to almost stalling then pick up after a few seconds. I extended the 3" inlet pipe another 6" - 8" away so the filter is righ into the corner behind he headlight and the reversion stopped ;-)
 
Jonesy

Jonesy

Member
It's a sard bov, it was already fitted to the car when i got it. Its just the last pulsar i had never done this. I'll get some photo's later on.
Also my intake pipework is also pretty short.
 
stevepudney

stevepudney

GTiROC CHAIRMAN
Staff member
Jonesy said:
It's a sard bov, it was already fitted to the car when i got it. Its just the last pulsar i had never done this. I'll get some photo's later on.
Also my intake pipework is also pretty short.
Click to expand...
What turbo is on this car ?
 
C

CanadianR

Member
youngsyp said:
If the car is physically jerking, you may have an engine mount or engine damper that's gone ?!
Click to expand...
I think my front one is knackered. Did you just remove it and fill the spaces with silicone?

My car does the same thing, fluttering. I still have the stock dump valve on, just a larger pipe run, I'd assume that the longer pipe run has more air that needs to be let out. Not really worried, should I be?
 
Y

youngsyp

New Member
CanadianR said:
I think my front one is knackered. Did you just remove it and fill the spaces with silicone?
Click to expand...
That's right mate. It might take a little while to dry but, it makes the bush better than new !
 
antgtir

antgtir

New Member
Sikoflex is the best material to use, it sets basically like a solid mount, great stuff and alot of people use it as a cheaper option to solid aftermarket mounts.

Sounds more like what Steve has highlighted as your piperun is very short from the turbo to MAF, may be worth lengthening this and see if that helps any.

Ant.
 
Y

youngsyp

New Member
antgtir said:
Sikoflex is the best material to use, it sets basically like a solid mount, great stuff and alot of people use it as a cheaper option to solid aftermarket mounts.

Ant.
Click to expand...
Ant,

Do you mean Sikaflex ? And if so, which grade ? There seem to be a few.

Paul
 
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