wastegate?

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what is the whole point of a wastegate in a turbo kit? what does it do?

posted by  silvia_star

Regulates the flow of exhaust gas through the turbine for closed loop control of the boost.

posted by  Wally

a wastegate makes a boost cut so that the turbo can't over load and fry itself.

basically, a 42mm wastegate has a stock 21psi boost cut, in other words, when ur turbo spools up to 21psi, the boost will just die out and you'll be stuck with engine again.

posted by  HyundaGuy

Want to revisit that post HyundaGuy :wink2:

posted by  Wally

Check this link out, its a pretty good explination.
Basically just what is said above, but with pics.

http://members.shaw.ca/dsm.1000q/Engineprimer/2G/wastegate.htm

posted by  Masuk

nah mate, i'm cool, i asked my brother that question two years back and he gave me the exact answer, also, if you unscrew the actuator out, you increase the boost cut, thus giving you a chance to run higher boost without having a cut.

it's kinda like a fuel cut, so my brother told me.

posted by  HyundaGuy

a turbo turbo works off of exhaust gas exiting the motor. As the turbo spools it forces more air in the motor thus creating more exhaust gas. Without a wastegate the turbo and motor would run in a positive feedback loop where more and more air and exhaust are forced into the motor. A wastegate bleeds off the excess pressure at a certain point, usaually 7psi unless adjusted higher, without it your motor would "pop" for a better explantion. check out this article (http://www.turbosaturns.net/articles/wastegate101.htm) for a detailed description and a few pictures

posted by  airmanUSN

if you wanna get into how boost is released into the atmosphere then you'd have to include a t/b, dump pipe and bov.

when you let go of the throttle, the t/b closes, the boost travels through the dump pipe, hits the butterfly lid of the t/b, does a complete 180, goes back through the dump and goes out of the bov, mainly because the bov is mounted on the dump.

a wastegate is mounted to the turbo itself and does actually cut itself off when reaching a certain level of boost, as i said earlier.

posted by  HyundaGuy

OK I'll get around this a different way:

the wastegate is the little penny that swings open to bypass exhaustgas around the turbine. The size of the oriface is determined by the mass flow rate of the exhaust and is nor an arbitrary size. Small turbos may only have an 18mm oriface and large ones may be larger than the 42mmm nominal you raised.

The wastgate is actuated by the wastegate actuator. Dependant on what bellows size and spring tension the actuator will begin to open at a preset error between actaul boost and desired boost. To shift this preset guys install a boost control solenoid or stepper motor valve to reduce the pressure the actuator sees.

So staying on the wastegate itself. If your oriface is too big it will bypass exhaust gas too rapidly and boost will drop sharply, if it is too small the boost pressure will creep above the desirable threshold. If the actuator is too slow and/or the oriface is too small the boost will spike and cause a boost cut via ignition cut or fuel cut. If the wastgate is too slow and/or the oriface too big you risk boost hunting, unless you have a boost controller that has integrating (speed ) and differentiating (rate) functions.

posted by  Wally

the BOV, dump tube and throttle body have nothing to do with his question or my response.

the wastegate and BOV,while similar, are two completely different things. the BOV only opens when, like you said, after accelleration with the release of the throttle under boost. the wastegate can release pressure both immediately after release of the throttle and during accell. to prevent the turbo from spinning to fast and creating to much boost

posted by  airmanUSN

the easiest way to explain it is both the wastegate and blow off valve are activated by vacuum once your car reaches a certain boost level the wastegate opens not letting anymore boost build up therefore stopping at a certain boost level...but unlike what hyundaguy said you car dont run off just the motor it stays at that boost level...and the blow off valve after reading boost and then letting off the accleerator it goes to vacuum opening the blow off valve so it vents the air out and not back into the turbo.....because it causes compressor surge and can ruin your turbo....if i made some mistakes feel free to correct just my :2cents: ...thanks for reading

posted by  black_plague

the easiest way would be to actually do another search (yet again) in these forums for the various well explained posts that have this information very well explained already.................

posted by  Inygknok

sorry if i've given a wrong description of what goes on with a wastegate, that's just always what i've been told it does, i was told by a mechanic at toyota that the wastegate is a boost cut that cuts off the turbo at a certain boost level to insure it doesn't over boost/spool up and rewind the turbine.

sorry if i gave the wrong answer.

posted by  HyundaGuy

Yeah, but chances are you could find a verbatum description quicker, by Googling it :wink2:

posted by  Wally

wtf does verbatum mean?

wow wally, you sure do use big words...

^^^^ STOLEN FROM STEVE! :D

posted by  HyundaGuy

HEY thats mine... :laughing:
It is part of the vertebrae and brain :screwy: :laughing:

posted by  99integra

thanks steve, i love you :)

posted by  HyundaGuy

Just keep it in your damn pants brudda :wink2: :laughing:

posted by  99integra

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