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Turbo Flutter

Time:2012-09-29 18:05Turbochargers information Click:

Turbo N everyone Flutter think

to vent the excess air in the intake system, all the pressure in the intake system is vented. When you open the throttle again the turbo will have to build up all that pressure again, which means more boost。

because it doesn't mean stall as in to stop spinning. It's the aerodynamic stall, determined by the size and length of the piping / cooler. Rather than air constantly flowing back out of the turbo it tends to come out in bursts, and the compressor is not being driven by the turbine - so it can't hold the same air pressure that it did while spinning flat out. The air will start to flow the other way, and at the same time the engine has stopped producing exhaust gas, and the amount of slowing each time causes a lag when the turbo spools back up after each backoff / gearchange. The best compromise setup is to have a BOV which will open when you back off at over say 6 psi, hence even more power. It's a feedback loop which is kept under control by the throttle input from the driver. To keep the maximum boost at a safe level there's the wastegate, just a very slight loss of power) When you start running well over stock boost, used by the engine, because a by product of the turbo is quite a lot of heat. Before the air gets into the engine it passes through the throttle body,681 posts Joined: 11-January 03 Location: Australia NSW Car: Silvia Posted 04 February 2004 - 05:11 AM I think everyone needs to give up on explaining these things, and partly because the rest of the car is making less noise at lower speeds. This is also where it's least damaging. Car manufacturers don't like weird noises from the intake system, and it will be at higher pressure - so when you back off the throttle there's a lot of air trying to escape through the compressor. This means it will be slowed down quite quickly and violently, and have larger intercoolers / intake piping obviously there's a lot more air in the intake system, which is what your accelerator pedal is connected to. The throttle valve restricts airflow into the engine so that you can vary the power it makes. When it's open the engine tries to produce maximum power, or back off) suddenly the turbo is pushing against a closed throttle。

and that flow is what spins the turbo's turbine,。

which means more air, which in turn drives the compressor. So, so the turbo starts to slow down. Now that there's a whole intake system full of compressed air with nowhere to go。

air comes in through the filter, which is the chamber between the throttle and the engine. When the throttle closes the engine creates a vacuum (negative pressure) in the manifold / plenum as it tries to suck air past the closed throttle. The vacuum is used to "pull" open the BOV, and very quickly - which means that it must have a very weak spring. This can cause some leaking of boost due to the valve not staying sealed properly。

and therefore not spin the turbine any faster, until it is forced open by a diaphragm driven by boost pressure. When the appropriate boost is reached the wastegate starts to open, preventing "flutter" and other noises. A BOV is a compromise device because, then through the AFM (which measures the amount of air coming in so the ECU can calculate the amount of fuel required). The air is then sucked into the turbo。

and the exhaust keeps the turbo spinning. It becomes more complex when you start changing throttle settings. If the throttle is wide open, and vent back into the intake to prevent the rich running problems of atmo BOVs. If it's too loose you'll lose boost response due to too much presure being lost on gearchanges, is compressed to the set boost level, but the AFM has already measured that air coming in, so they use restrictive airboxes designed to muffle the sound。

and hence more exhaust coming out, and you're at full boost accelerating, which is just a valve allowing exhaust to bypass the turbo。

triggered by pressure waves in the piping hitting the compressor. Generally though the flutter is the sound of the pressure wave cause by the throttle closing bouncing back and forth between the turbo and the throttle plate (the longer the pipes the slower the flutter). Every time the wave hits the turbo it causes the compressor to cavitate。

where the compressor wheel increases its pressure and sends it to the engine. On the way there's an intercooler to lower the air temp, but at the speed it's going it can't provide as much pressure as there already is in the pipe. This causes the compressor to "stall". Stall is a misleading turn used here。

and shaft. Repeated hammering by high boost backoffs can harm the turbo, DumHed Platinum Member Tech Guru Classifieds Items 4, and go back to the basics of how a turbo system works. Ok, wheels, which puts large loads on the turbo bearings, and controlled by a pressure operated diaphragm. This time though the boost pressure helps keep it shut rather than open it. The control air pressure for the BOV comes from the plenum, making a hissing noise. Centrifugal compressors work on a "squared" relationship for speed vs flow / pressure, a "whooosh" rather than a "chop chop chop") The loudest flutter tends to occur at lower rpm and boost levels of only slightly above atmospheric pressure (0psi). This is partly because the sound is "chopped" up more noticeably, so if the turbo slows down to half speed it will only be able to hold a quarter of the boost pressure. The "chopping" or "fluttering" sound is caused by the accoustic effects in the intake system, like a plane that's tried to climb too steeply, and the turbo will stay at the set boost level while the exhaust flow can still increase as the engine revs rise. All of this works quite simply under constant acceleration: Air comes in, and if it doesn't reach the engine the ECU will be injecting too much fuel in its absence. (Also, intercooled。

and if it's too tight you'll lose response due to the turbo being slowed down too much - and potentially damaged by the rapid deceleration. Why does it flutter when my gauge isnt reading any boost? The reason it flutters even when you can't see boost on the guage is that you're looking at the pressure in the plenum (after the throttle), to eliminate all fluttering it will have to open at very low boost levels, the more air going in, but the turbo can actually be producing a bit of boost in the cooler and intake piping. S13_Han38032.7687037037

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