internal and external wastegates

[kyle_gtr]

ello im just tryiny to find out for friend whats the difference between a internal and external wastgate apart from the fact the 1 is inside and the other out side

and how would a screamer pipe sound on an internal wastegate??

thanks

 

[oilrag22]

Internal wastegate is mounted in the turbo housing itself, is hard(not impossible) to alter or change.

External is located in the business end of the exhaust, can easily be altered and tuned, springrates, diameter of wastegate valve, preload on spring and so on...

 

[180_BOY]

usualy bigger turbos have external waste gates that run off the manifold to the waste gate and the screamer pipe is usuely very loud.

internal is in the turbo its self and uses the actuator with an arm to open when required boost is obtained

 

[Bunny]

Should it sound the same though with a screamer pipe.

 

[Bunny]

i have a bigger turbo on my 200 but already built the internal wastegate. Therefore running a screamer pipe off that. I was told should sound ok but will be a bit blowy.

 

[180_BOY]

were the bit of metal splits the waste gate and the exauhst fan it wont be air tight so some gas will come out of there which is probably why i would think sounds better with external waste gate

 

[Bunny]

yeah that is what i been told. Won't be air tight. But it should do for the time being hopefully. But as long as it will pop and bang. LOL

 

[180_BOY]

lol what paul did on his 32 he got td06 welded a pipe from the internal waste gate to the external one then had a screamer pipe running off that sounds pretty awesome actualy lol

 

[Bunny]

so he had an external wastegate and internal.

I think that the internal one will open under throttle. Does it do the same as an external one.

 

[kyle_gtr]

can any 1 find a vid of an internal waste gate with a screamer pipe cause i cant
please

 

[superclarkey]

Internal wastegate screamers are extremply gay ! it sound liike a leaky turbo, why anyone would want that i don't know.

They always sound crap imho.

block the internal one up, and weld a external one onto the manifold and do it right, the results are in the sound my firend

Do not fit an internal screaemer, its just wrong.

 

[kyle_gtr]

ok thanks there you go bunny theres ur answer

 

[superclarkey]

yeah that is what i been told. Won't be air tight. But it should do for the time being hopefully. But as long as it will pop and bang. LOL

If you want it to pop and bang, let Mitto map it for you, it will make one loud pop and extreme bang

 

[kyle_gtr]

If you want it to pop and bang, let Mitto map it for you, it will make one loud pop and extreme bang

sounds like a plan when i get my car

 

[Mr Bizzle]

If you want it to pop and bang, let Mitto map it for you, it will make one loud pop and extreme bang

I wouldn't trust mitto to read a map, let alone map a car.

Pretty much as clarkey said -
A waste gate's purpose is to limit the amount of exhaust gas entering the turbo from the manifold. When your turbo is spooling, the waste gate is shut tight which let's all the gas from the manifold flow up and into the turbo (creating boost) When the required boost level is achieved, the waste gate opens, venting off exhaust gasses to keep the turbo producing the correct amount of boost pressure.

Most of us are familiar with the internally gated turbo (on your standard Nissan turbo’s etc) These vent gas at the mouth of the exhaust housing and dumping them straight into the exhaust stream. This can have two detrimental effects. 1) Causing turbulence in the exhaust stream reducing performance 2) On larger turbo's the waste gate is physically not big enough to vent enough gas to keep the boost to an acceptable level.

An external waste gate vents off excess exhaust pressure from the manifold (before it even reaches the turbo) Most modern system vent the excess exhaust gas (via a pipe) and place it further down the exhaust system. However some people opt for a "screamer" pipe, which vents these gasses straight to atmosphere. An external waste gate has two key advantages 1) The waste gate it's self is much larger and more complex, with different spring rates available. This makes boost much more controllable. 2) It eliminates the turbulence caused by vented gas being purged into the exhaust stream right by the turbo.

Unfortunately, the "screamer" pipes that vent internally gated vents to atmosphere are actually not beneficial to performance. Because you can never get a good seal, they act like a blowing exhaust - which sounds poor and is detrimental to performance.

Hope that helped somebody.

 

[tunermt]

Here is a great article for internal vs external wastegate

pictures and diagrams as well to ensure a clear understanding of exactly how both internal and external wastegates work.

 

[tunermt]

Recently tuned a STI EJ25 running a GTX3576R and a tial MVS wastegate. In this particular example the MVS wg was vented to atmosphere* While this is not a common engine choice for drifting the boost creep concept still directly applies.

The log above shows less than 2% duty cycle to the boost solenoid which means the engine will run at the lowest possible boost AKA "wastegate spring pressure". You can see the white line (boost) climbs quickly then tries to "level off" as the wastegate opens at ~15psi. However do to the MVS wastegate being a bit to small for the EJ25 and GTX3576R turbo combination you can see the boost continues to climb from 15psi up to 20psi by 4800rpm at which point it starts to taper back down as the turbo/engine combo becomes less efficient. 15psi creeping to 20psi or 5psi of boost creep is more than ideal, at most 2-3psi of boost creep would be considered acceptable. Now keep in mind this 5psi of boost creep happened in only 3rd gear, as the engine is loaded up/ran at WOT (wide open throttle) in 4th, 5th and 6th gear the engine will be under load for longer resulting in even more boost creep than we can see happening in the 3rd gear pull. If you look further to the right in the log you can see as the car continues to accelerate in 4th gear the boost creep becomes more severe and boost creeps 6psi over wastegate spring pressure before 4800rpm while in 4th.
In this case there are 3 options:
-add a second MVS wastegate or replace the existing MVS with an MVR or other 44/45mm wastegate (more exhaust volume/flow can move out the wastegate/s)
-Lower the spring pressure in the wastegate. This will allow the wastegate to open earlier making it slightly easier to manage the boost creep and keep "peak boost" at the target. (this is a band-aid fix that simply accounts for the boost creep by opening the wastegate at a lower boost target, this is works but will limit the amount of boost you can target at lower RPM as you must still account for the creep.)
-recirculate the wastegate dump to the downpipe. (this will only help lower creep 1-2psi) as the wastegate bleeds pressure into the DP the pressure differential on the turbine wheel is decreased even further than if the wastegate was vented to atmosphere.