Usefulness of wastegate

[Joeker]

Wastegate sound can be tuned actually.

By playing around with the length, the dia. and the tip size of the wastegate's screamer pipe, you get different sound effects.

My all time favorite wastegate sound is like that of a lorry with a punctured exhaust pipes.

 

[jeffblazed]

Wastegate sound can be tuned actually.

By playing around with the length, the dia. and the tip size of the wastegate's screamer pipe, you get different sound effects.

My all time favorite wastegate sound is like that of a lorry with a punctured exhaust pipes.

prap..................prap......prap.........sound......

 

[kelvio]

i tot BOV that produce the pisssss pisss sound 1 what kind of sound do wastegate produce??
still nood in turbo

 

[Fluffy]

i dont use a wg..so like joeker said..it can be diff types of sounds...

 

[alvin24]

wei dude thats the sound of 2 bov plus 2 wastegate....i heard it before damn syiok la.....but very hard to get that setup cause must use small waste gates...with slightly different settings....bov also same.....

ok...from my understanding the wastegate is used to control the exhaust gas preasure which is pushing the exhaust turbine.....
so to much preasure u get the........... prap sound



while the bov is used to control the boost preasure of the of the compresor turbine...... to much preasure u get the..... piss sound

so the to much preasure part depends on you setting la.........like me i prefer a small waste gate setting plus small bov setting so i can whack my turbine kow kow........cause i using big cap ayam turbine which has alot of lagg.....but when the boost come in ...fuuyooo......depends on user la...some prefer responce...

Ummm... i think this isn't all accurate... =Þ

Wastegate is used to control exhaust flow rate actually... not exactly the pressure. This is so that you can control the amount of exhaust gasses to flow thru the exhaust turbine... the exhaust turbine works as a driver for the compressor turbine... therefore by controlling the exhaust turbine, u're actually controlling the amount of boost built by the compressor turbine.

Wastegates are tuned so that when u reach the desired boost,the wastegate opens and lets excess exhaust gas thru the wastegate to bypass the turbo.

The BOV has nothing to do what-so-ever with the pressure built by the turbo... if your BOV emits a sound while u're on full throttle means your BOV is leaking and needs replacement! =) ehehe...

The BOV's duty is to release all pressure between the turbo to intake manifold when u're off throttle... coz' if the throttle is closed... The pressure built will have no where to go but back where it came from, therefore the turbo will experience a big back pressure... which will of course damage your turbine.

 

[alvin24]

Actually... now come to think of it... could it be blackie uses 2 wastegates so that the powerband is more linear... therefore more drivable on the streets?? =Þ

 

[VANILLA]

the BOV is there to dump the air out when the intake closes so that the compressor doesnt surge = drop speed. people also tune it so that it prevents overboosting. or they get an extra for that.

of course there are a lot of sizes on WGs. If we all could afford to put an RM4K HKS 60mm GTII into our car wed all be doing it:)

 

[VANILLA]

or maybe he has a split inlet on his turbine? so he uses one WG on each pulssplit pipe??

 

[jeffblazed]

Ummm... i think this isn't all accurate... =Þ

Wastegate is used to control exhaust flow rate actually... not exactly the pressure. This is so that you can control the amount of exhaust gasses to flow thru the exhaust turbine... the exhaust turbine works as a driver for the compressor turbine... therefore by controlling the exhaust turbine, u're actually controlling the amount of boost built by the compressor turbine.

Wastegates are tuned so that when u reach the desired boost,the wastegate opens and lets excess exhaust gas thru the wastegate to bypass the turbo.

The BOV has nothing to do what-so-ever with the pressure built by the turbo... if your BOV emits a sound while u're on full throttle means your BOV is leaking and needs replacement! =) ehehe...

The BOV's duty is to release all pressure between the turbo to intake manifold when u're off throttle... coz' if the throttle is closed... The pressure built will have no where to go but back where it came from, therefore the turbo will experience a big back pressure... which will of course damage your turbine.

which part not accurate.......flow rate?////????........toomuch flow=high preasure la dude.......waste get does not have a flowrate sensor la it function on preasure...... dude pls tell us all how the wastegate can detect flow rate........and open.....compress air is related to preasure.......thats why our boost meter reading is in psi or bar ....where got boost meter show flow rate........pls learn the diffrence of preasure and flow rate before commenting.......

 

[VANILLA]

ya it functions on pressure and you take the signal any where after the turbo to before the intake. the earlier the better response...

 

[Fluffy]

ok...from my understanding the wastegate is used to control the exhaust gas preasure which is pushing the exhaust turbine.....
so to much preasure u get the........... prap sound

preasure?there's no preasure.its the exhaust flow..its flows THRU the wastegate to bypass the turbine.

while the bov is used to control the boost preasure of the of the compresor turbine...... to much preasure u get the..... piss sound

the BOV does NOT controol anything.it is just to release the excess preassure to avoid a surge.

 

[Dino@Casper]

Let me try to explain... As we all know the turbine is spin by the exhaust gas....

So we also know that the wastegate is to prevent overboosting, so it actually means once the pressure inside the turbine reaches a certain level the wastegate would open to let the extra exhaust gas out right?..

now let me try to get more theoritical with the question.. Pressure is directly related to the velocity of the flowing gas.. is also depends on the Area which is the size of the waste gate...

Okay in Fluid dynamics that i learn.. 3 basic concepts that we always apply.. but for this discussion let me cut it short.. anyone out there please correct me if i'm wrong.. cause i haven't be doing fluids for quite some time..

If we consider a system.. A open sytem like the exhaust for instance, which we actually have to have a control volume, in a control volume like this we actually would need to consider the following... The HEAT release and the Work Done should equal to the kinectic engery, potential energy and pressure energy.. this 3 energy are what makes the system... so they are actually closely related to each other.

After some elimination here and there basically not sure if this correct can't find my book just derive myself pressure = Velocity*mass flow rate / area..

So as u guys can see if u increase the pressure and the mass flow rate and area is constant you would actually increase the Velocity and the formula for mass flow rate is actually density*area*velocity subsitute everything u can actually see how they are related.. thats for explain pressure and velocity the speed.. which i believe in all explanation its correct.. because both mention either when the speed builts up or pressure builts up.... And to be honest.. most systems that messure speed right are actually pressure sensors that later convert the values back to speed, like those in an aircraft..

As for boost meter why do u see in BAR.. or psi.. the pressure will give u a ratio of air being drawn into ur engine.. i mean come on if u see it in flowrate.. man u gonna have hard time figuring out how much air is actually going into ur engine.. for instance 1bar.. oh good.. so u know there is twice the amount of air going into your car.. as compare to normal.. u wanna see flow rate can.. but for what?... depending on what is the objective of the device u will see what u need.. like exhaust gas when we design we also need to know at what speed the exhaust gas is actually exiting.. thats important.. so i would say here velocity n pressure would also need to be considered..

Okay n finally just to make it final.. WASTEGATE is operated by a pressure sensor..

The Wastegate
Most automotive turbochargers have a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses the boost pressure. If the pressure gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down. (Qoute: How Stuff Works)

And all the BOV does is release the air so that u there is no surging effect on ur turbine which slows down the turbine drasticly and if you still dun understand this is http://en.wikipedia.org/wiki/Blow-off_valve the website for understanding.. tq

 

[Joeker]

preasure?there's no preasure.its the exhaust flow..its flows THRU the wastegate to bypass the turbine.

the BOV does NOT controol anything.it is just to release the excess preassure to avoid a surge.

Exhaust gases flow at a very hi temperature. When the exhaust gas is heated, it expands and causes pressure.

Jeffblazed is rite about the exhaust pressure that a wastegate regulates.

That is reason why in certain cases, overboost is caused by exesive exhaust pressure from improper A/F ratio or ignition timing.

A BOV controls how responsive the engine is.

Imagine a BOV that vents at the slightest +VE. This causes the much needed boost buld-up to be wasted and having the compressor to start building boost from square one. And in MAF sensored engine like 4G9/63s, causes engine stalling due to misintepretation of the ECU that air is still being digested despited the throttle being shut off.

But having too stiff a BOV diaphram or spring will cause backpedalling.

Therefore, BOV regulation is a fine line between anti backpedalling against boost buil up.

 

[imoloq]

which part not accurate.......flow rate?////????........toomuch flow=high preasure la dude.......waste get does not have a flowrate sensor la it function on preasure...... dude pls tell us all how the wastegate can detect flow rate........and open.....compress air is related to preasure.......thats why our boost meter reading is in psi or bar ....where got boost meter show flow rate........pls learn the diffrence of preasure and flow rate before commenting.......

Actually flow rate and pressure are 2 different things.

Flow rate is measured in ft/min or other similar units while pressure is measured in psi or bar. A high flow rate doesn't mean high pressure and vice versa. For example, your intercooler may have some blockage that impedes the air flow. So, in this case, pressure is high but flow rate is low.

However, a wastegate functions on pressure. Here's something I got from www.AstraSport.co.uk Club Forums:

Let’s begin by describing what a turbo wastegate is. A wastegate is essentially a device that bypasses some exhaust flow around the turbine section of a turbocharger to control maximum boost. A wastegate is usually controlled by a pressure actuator that is connected to manifold pressure. The wastegate is normally closed, held shut by a spring inside the actuator canister. When preset pressure limits are exceeded, the actuator progressively opens the wastegate, allowing exhaust flow to bypass the turbine, thus regulating manifold boost pressure. On the surface, it sounds like a simple premise, and in fact, a wastegate is a simple device. The problem comes from the pressure in the exhaust system, called turbine inlet pressure that can bear against the valve, overpowering the spring in the actuator, and forcing the wastegate open at lower than intended boost levels.

Original equipment turbocharger wastegate actuators are selected or engineered for a specified boost level and turbine inlet pressure. To keep costs down, such actuators are usually just big enough to do the job at the stock boost levels. If the turbocharger boost is increased for additional airflow and performance, the stock wastegate actuator is frequently incapable of holding the wastegate fully closed until the higher boost level is reached. This happens because turbine inlet pressure also increases as boost pressure rises. The fix is to use a bigger spring in the wastegate actuator to hold it closed until the desired peak boost is achieved, however, that also requires a bigger actuator diaphragm to override the heavier spring when the desired boost level is reached.

 

[alvin24]

which part not accurate.......flow rate?////????........toomuch flow=high preasure la dude.......waste get does not have a flowrate sensor la it function on preasure...... dude pls tell us all how the wastegate can detect flow rate........and open.....compress air is related to preasure.......thats why our boost meter reading is in psi or bar ....where got boost meter show flow rate........pls learn the diffrence of preasure and flow rate before commenting.......

hahaha... perhaps u'll want to grab a fluid dynamics book and turn to the pages with the topic turbo machinery. U want? I can lend u... hahaha.

The flow rate influences the turbine speed more than the pressure does. I never said u were wrong... i just said u aren't all accurate... the turbine will try its best to run at the same speed the exhaust gas is moving... thus the reason why i said the exhaust flow is mainly what influences the turbo speed (which then determines the amount of boost created). No doubt there's pressure building when the turbo isn't spinning as fast as the exhaust gasses... but thats not mainly what pushes the turbo... its more of a, can say, negative effect la. hehe...

I already said wastegates are tuned so when you get your desired boost... the wastegate opens to let exhaust gasses bypass the turbo. So obviously the wastegate has to get its readings from the intake boost pressures lah...

I never said wastegate uses flowrate sensor to work also...?? Which part says that?? hahaha.... and since we're arguing about exhaust pressure... i don't get what the boost meter gotta do with any of our arguments ?!? hahaha... and I don't remember seeing people selling 'exhaust press' meters either! hahaha...

Seems like u got facts i just bantai write only regardless of whether its related or totally useless information for this argument. =Þ hahahah...

 

[VANILLA]

ok u take a hose from after the compressor and route it into yer boost controller. when the BC measures your desired amount of boost it opens the WG. tadaaa!

there are 2 way BOV that u can tune to open when overboosting. or u can get a second one to do that.

end of story:)

 

[jeffblazed]

hahaha... perhaps u'll want to grab a fluid dynamics book and turn to the pages with the topic turbo machinery. U want? I can lend u... hahaha.

The flow rate influences the turbine speed more than the pressure does. I never said u were wrong... i just said u aren't all accurate... the turbine will try its best to run at the same speed the exhaust gas is moving... thus the reason why i said the exhaust flow is mainly what influences the turbo speed (which then determines the amount of boost created). No doubt there's pressure building when the turbo isn't spinning as fast as the exhaust gasses... but thats not mainly what pushes the turbo... its more of a, can say, negative effect la. hehe...

I already said wastegates are tuned so when you get your desired boost... the wastegate opens to let exhaust gasses bypass the turbo. So obviously the wastegate has to get its readings from the intake boost pressures lah...

I never said wastegate uses flowrate sensor to work also...?? Which part says that?? hahaha.... and since we're arguing about exhaust pressure... i don't get what the boost meter gotta do with any of our arguments ?!? hahaha... and I don't remember seeing people selling 'exhaust press' meters either! hahaha...

Seems like u got facts i just bantai write only regardless of whether its related or totally useless information for this argument. =Þ hahahah...

dude i already got the fluid dynamics book ...i stole it from the library while doing my degree in mechanical engineering....a few years back......i also use to design piping systems for factory in my old company....thats why everything around a turbine in an engine revolves around preasure and not flow......there is also positive preasure and negative preasure(vaccum)........

 

[Joeker]

there are 2 way BOV that u can tune to open when overboosting. or u can get a second one to do that.

end of story:)

Mechanical BOVs require 2 signals to operate. Vacumn signal from intake manifold and Boost signal from compressor. BOV wount be able to regulate overboost

To control overboost, a pneumatic relieve valve like the ones used on CART racers in US would be more viable.

I think the Americans call it "POP OFF" Valve. (saw this in Discovery Channel "SPEED WEEK")

 

[TitanRev]

Blackie needs 2 wastegate because his exhaust is very damn de loud..the exhaust sound empowered the wastergate sound already so he need 1 more to balance mah..or his ear not sensitive already because too much loud exhaust from his monster...cant hear the wastegate sound so install 1 more.....hehehehe:_: *cabut*

 

[Joeker]

I tot I saw 6 wastegates, 1 for each piston.