Time for a new dose pipe!

[Psycho Chicken]

http://www.youtube.com/watch?v=VbNxugO-uf0

[mcflux]

http://www.youtube.com/watch?v=lZG0RS3mVBc

[EDIT] 56k sucks... [/EDIT]

[montyv8]

Originally Posted by T_Terror

When i had my 180sx it would do hardcore flutter but no dose.

Didn't someone say flutter = dose?

[AshMan]

Originally Posted by dansedgli

Post number 5100 for me :P Damn ninja's! :

When you slam your throttle shut and have no BOV the air in the intercooler piping is forced back through the turbo and past the air filter. The dose sound is the air rushing back through the wheel. Its called reverberation or something like that as well. Also known as flutter.

I think the term you're reffering to is "cavitation"

[mcflux]

I thought cavitation occurred in water pumps?

[T_Terror]

Originally Posted by montyv8

Didn't someone say flutter = dose?

Isnt dose the high pitched flutter?

I thought flutter was the fff fff fft ffftt sound like a flap rapidly opening and closing which is what you usually hear in imports and 4.0Ls.


ill be honest, im not fully sick just yet...

[AshMan]

Originally Posted by Ghia5L

I thought cavitation occurred in water pumps?

Pumps in general... Turbo = Air Pump

Also fans and propellers can experience cavitation...

[mcflux]

But isn't it only for liquids? IE when the impellor moves too fast and creates a low pressure area in the liquid, a void is formed in the liquid which then collapses on itself again. This void/collapse is the cavitation and the energy produced from this can cause pinholes/blowouts/corrosion to the impellor blades.

Gas would merely expand and reach really low pressures, thus avoiding cavitation. Wouldn't it? I'm happy to be corrected on this.

PS Gir rocks!

[SileNceR]

More boost will fix it sunny!

[TUFED6]

The term Dan meant is reversion, not cavitation.

[oneredED]

Originally Posted by K&N Filters Website

In an automotive application, reversion refers to reversed air flow, or in simpler terms, it’s when air in the intake runner reverses direction for a split second. The condition is caused when a burst of pressure escapes into the intake runner from the cylinder during valve overlap.

Reversion creates resonance shock waves inside the tubes which exit the open end of the tube at various rates depending on engine speed.

Not quite applicable, but a close definition of "reversion". I'm obviously bored.

[AshMan]

Originally Posted by Ghia5L

But isn't it only for liquids? IE when the impellor moves too fast and creates a low pressure area in the liquid, a void is formed in the liquid which then collapses on itself again. This void/collapse is the cavitation and the energy produced from this can cause pinholes/blowouts/corrosion to the impellor blades.

Gas would merely expand and reach really low pressures, thus avoiding cavitation. Wouldn't it? I'm happy to be corrected on this.

PS Gir rocks!

I stand corrected.

–noun 1. the rapid formation and collapse of vapor pockets in a flowing liquid in regions of very low pressure, a frequent cause of structural damage to propellers, pumps, etc.

I thought cavitation was when the liquid or gas was forced back through the turbine...

Oops : :

[snortingboost]

Originally Posted by dansedgli

You dont hear these cars dose because they dont get off the throttle that often.

With antilag in rally and race cars, the turbo doesnt behave in the same way as a street car. Its continues to spin even with the throttle closed.

A drag car isnt going to get off the throttle half way through his run.

A BOV is another thing that can leak boost and break, lots of people think they are unnecessary.

Actually I think there has been tests done and the dosing that you hear is less likely to slow the car down that a good BOV as the intake tract doesnt lose all of its air. The BOV releases it all to atmosphere while with no BOV only a small amount gets out back through the turbo before the next gear is selected.

Oh and a BOV wont always stop a car from dosing. In my AU with a GFB Stealthfx BOV if I didnt dial up more than 12psi and release the throttle the car would dose as the BOV wouldnt open.

Dude, if 'people' 'think' that BOV's are going to cause more problems than what they solve, why is it that every turbo factory vehicle and 99% (1% made up by fellow doser's) of performance enhanced vehicles have them? Without a BOV you will after some time hurt your turbo especially if you run high boost. I don't care what you do but this above info isn't good practice, just ask the professionals.

[EFFalcon]

every turbo vehicle?
VLT's don't have BOV's do they?

[snortingboost]

Originally Posted by EFFalcon

every turbo vehicle?
VLT's don't have BOV's do they?

I said high boost didn't i?

[snortingboost]

and there was a 1% made up by fellow doser's, so there. lol.

[EFFalcon]

Originally Posted by snortingboost

why is it that every turbo factory vehicle and 99% (1% made up by fellow doser's) of performance enhanced vehicles have them?

you said what now?

every

[snortingboost]

Even though i wouldn't do it to my car as the screamer pipe is good enough to let everyone know what's lurking, i think you might find using 2.5 inch pipework that is very short in total length may contribute. Having 3inch with a massive intake length will act as a plenum which inturn will cusion the pressure waves between the throttle plate and compressor. By the way whats a vlt, a vacant left testie?

[snortingboost]

Originally Posted by EFFalcon

you said what now?

every
single

Damn, your just far too clever, must have been top of the class sitting right up the front. Who would have thought a factory turbo car wouldn't come out with a blow off valve? Holdens always seem to be just missing out on something, the nissan engine was missing out on oil leaks so they had to come up with something i suppose.

[dansedgli]

Originally Posted by snortingboost

Dude, if 'people' 'think' that BOV's are going to cause more problems than what they solve, why is it that every turbo factory vehicle and 99% (1% made up by fellow doser's) of performance enhanced vehicles have them? Without a BOV you will after some time hurt your turbo especially if you run high boost. I don't care what you do but this above info isn't good practice, just ask the professionals.

Im not arguing that running no blow off valve will shorten the life of your turbo. Even if its not proven to help its better to spend $200 on a BOV just in case rather than rebuild a turbo.

How is it not an extra thing to worry about though? If its not there then its not cant cause a boost leak hence you dont need to worry about it.

Are you a professional?

[ScoopED]

I'm sorry if someone has already said this.... Or if I am terribly wrong.....

Not having a blow off valve causes the compressors airflow to 'back up' and build pressure to the point that it blasts back through the compressor inlet when the throttle plate closes.... right???

Now, wouldnt this cause the compressor wheel (and turbine wheel) to slow down rapidly???

I wouldnt think that this is very good, as you would probabarly be getting a brief, yet massive boost spike in your inlet manifold and intercooler piping (pre throttle body). Probabarly not the best thing to happen.

Then you may have the issue of the massively hot exhaust gasses still trying to hammer past a temporarily stalled or slow moving turbine wheel. I'd say that this is not the healthiest thing to happen to one of these highly stressed components.

With the spiking pressures in a system such as this, I would say that by leaving the BOV out of the system, you would also be generating extra heat throughout the system aswell.

I may be completely wrong.

Mike

[snortingboost]

Originally Posted by dansedgli

Im not arguing that running no blow off valve will shorten the life of your turbo. Even if its not proven to help its better to spend $200 on a BOV just in case rather than rebuild a turbo.

How is it not an extra thing to worry about though? If its not there then its not cant cause a boost leak hence you dont need to worry about it.

Are you a professional?

Yes, i'm a professional, just ask me.

[dansedgli]

Ok in your professional position, how many turbos have failed as a direct result of not using a blow off valve?

Which blow off valve would you recommend for a high boost app?

Are all blow off valves created equal?