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I'm Ticked Off...what Gets You Wound Up?

LTSJayce

By LTSJayce,
in Australian Capital Territory

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Gus- Grand Master

Gus-

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haha dose is when you block off the bov....so when foot comes off the accell all the back pressure has no where to go...goes back past the turbo out the intake and at the same makes a sick as sound

vrrrrrrr tututututututu

search youtube for dose and youll see what i mean.

Bullet32 Veteran

Bullet32

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haha dose is when you block off the bov....so when foot comes off the accell all the back pressure has no where to go...goes back past the turbo out the intake and at the same makes a sick as sound

vrrrrrrr tututututututu

search youtube for dose and youll see what i mean.

Why would you want to increase inlet reversion?

I know its a "fully hectic" noise but your turbo wont last long... I cant stand people who turn a nice car into "all show no go". :)

LTSJayce Veteran

LTSJayce

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Why would you want to increase inlet reversion?

I know its a "fully hectic" noise but your turbo wont last long... I cant stand people who turn a nice car into "all show no go". :)

2nd that! This falls right into the topic of what ticks me off!!

MIVEC Mentor

MIVEC

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Er.....I'm sure someone more mechanically minded will step in after but.....wouldn't not having a BOV causes compressor surge in the first place?

All turbo cars require a blow off valve for particularly that reason.

LTSJayce Veteran

LTSJayce

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depends if its compressor surge or if its cause you dont have a BOV

Both can happen, but the first is guaranteed if you don't have the second one. MIVEC is right; anything turbocharged will have a BOV for this reason above all. Maybe there's some application out there in the world that's turbo'd without a BOV(combine harvester? marine ship's engine?)- can anyone here enlighten us on turbo'd non-BOV'd applications? It surely wont be a modern car engine.

Back on topic, and including the BOV side, I can't stand 'new' modifiers getting their first vent to atmo BOV and setting it so it vents at the slightest hint of closed throttle. 1500 rpm gently off the lights, then WHOOSH...well done, son: you're officially 'Too Fast, Too Furious', and fooly hektic, too.

rossco_01 Rising Star

rossco_01

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Er.....I'm sure someone more mechanically minded will step in after but.....wouldn't not having a BOV causes compressor surge in the first place?

All turbo cars require a blow off valve for particularly that reason.

yeah they do except turbo diesel as my olds car doesnt have one

compressor surge isnt bad for the turbo it just runs hot air back through you AFM which isnt good for the ecu and dumps more fuel into the motor causing it to run rich which in turn causes detenation= bad

the myths of turbo's shattering cause of compressor surge is bull**** i had a mate with an rs liberty with no bov runing 20psi huge flutter and it has been running for 10 years on that setup turbo is fine no shaft play still spins true its just when he backed off the engine light came on to warn him that it was either "over boosting" or detenating

LTSJayce Veteran

LTSJayce

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yeah they do except turbo diesel as my olds car doesnt have one

compressor surge isnt bad for the turbo it just runs hot air back through you AFM which isnt good for the ecu and dumps more fuel into the motor causing it to run rich which in turn causes detenation= bad

the myths of turbo's shattering cause of compressor surge is bull**** i had a mate with an rs liberty with no bov runing 20psi huge flutter and it has been running for 10 years on that setup turbo is fine no shaft play still spins true its just when he backed off the engine light came on to warn him that it was either "over boosting" or detenating

I personally know of a turbo that came to grief when just that happened, albeit with nearly 50 psi of pressure, and many hard years of drag use on it's resume beforehand. For whatever reason, the BOV's (two of them) basically didn't operate just once(we looked for a line off, etc, but it all looked OK at the time), so the huffer was always the first point of failure in it's trim. T'was an impressive failure, too. The rebuilders at GCG said the BOV's had to be the reason for the failure, at those levels. Who am I to doubt them? Said car has changed set up(from a 1.5JZ to a 2JZ, and a BST to twin high rise), so here we go again...

So, in line with the topic, my friend was pi**ed off at faulty BOV's!!

LTSJayce Veteran

LTSJayce

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^^^ fair point but i have one question was the turbo rated to run at 50 psi ???

Yup. It had just done so for a bit too long. My mate confessed that he should've given it an overhaul a few months before it went BOOM. Ah, well: he learnt from all of this!

Bullet32 Veteran

Bullet32

Posted
Posted
yeah they do except turbo diesel as my olds car doesnt have one

compressor surge isnt bad for the turbo it just runs hot air back through you AFM which isnt good for the ecu and dumps more fuel into the motor causing it to run rich which in turn causes detenation= bad

the myths of turbo's shattering cause of compressor surge is bull**** i had a mate with an rs liberty with no bov runing 20psi huge flutter and it has been running for 10 years on that setup turbo is fine no shaft play still spins true its just when he backed off the engine light came on to warn him that it was either "over boosting" or detenating

Ok let me set this straight...

You are correct about the air going through the AFM and the ECU running the engine rich for a few seconds... However it isnt a myth that inlet reversion or compressor surge kills turbos...

Reversion of air pressure back across the turbo acts against the compressor wheel and causes the turbine to reduce speed quicker than it would naturally, this can often cause stress on bearings, the shaft and the wheel itself.

Also when the throttle is opened again, the turbo will have to make up for lost momentum and will take longer to achieve the required speed, hence more lag.

If your BOV is not set up proportionally to the pressure inside the inlet, at the point when the throttle closes the pressure cannot reduce quick enough and wont be able to escape through the BOV quick enough... This means that the only way for the excess air to escape is back through the turbo charger.

Your friends Liberty turbo may not be damaged due to the pressure not being enough to damage the internals of his particular turbocharger as most aftermarket turbos are much stronger than OE ones - which break more easily.

Inlet reversion or compressor surge mainly happens when an aftermarket BOV is installed and not set to the correct pressure, this causes the "fully sick" flutter noise and is actually a combination of pressure being released through the BOV gate and the turbo compressor.

Now I sit back and wait for the arguments :P

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