Forums
Posted By: red20 EXTERNAL WASTEGATE - 13th Aug 2006 11:04am
if i was to get this instead of a dump valve as i like the chatter noise alot more would i be able to fit this to my 200sx an if so how hard would it be
web page
Posted By: StuyMac Re: EXTERNAL WASTEGATE - 13th Aug 2006 11:23am
I had an external wastegate on my old S14a.

They dont make any chatter noise, they just vent the excess wastegate gasses to atmosphere rather than down the exhaust and are not any kind of replacement for a dump valve - they do different jobs.

To fit it you would need to buy a manifold with the fitment for your turbo and the external gate adapter as modifying std manifolds just doesnt offer the flow characteristics.

You would also need to weld the std internal wastegate shut to stop that working.

External gates are a high power mod and you would see no power gain from fitting it on a std turbo.

Theyn are also a pain in the backside to set up correctly, took me weeks and weeks to get the settings right to get an accurate boost setting frown
Posted By: scoop Re: EXTERNAL WASTEGATE - 13th Aug 2006 11:32am
The "chatter" noise does not come from the wastegate, a turbo MUST have a wastegate but doesnt NEED a dump valve/blow off valve. An external wastegate is just a way of venting excess exhaust gas BEFORE it reaches the turbine,this gas is either vented into the exhaust AFTER the Turbine or sent out to atmosphere. IT gives a noise as its venting but not a "chatter" noise. The chatter noise is gained by simply removing the dump/blow off/recirc valve giving the charge air nowhere to go but back thru the compressor blades.

External wastegates are considered more reliable than internal ones and are more easily adjusted
Posted By: red20 Re: EXTERNAL WASTEGATE - 13th Aug 2006 12:29pm
so wot gives the chatter noise i thought u only got a psssshhhhhh noise from a dump
vavle
Posted By: StuyMac Re: EXTERNAL WASTEGATE - 13th Aug 2006 12:36pm
When you shut the throttle the turbo is still spinning due to momentum in the blades. This means it still compresses the air, but has no where to goas the throttle body is shut. It therefore goes backwards and stalls the turbo. The chatter noise is the turbo stalling.

A dump valve releases that pressure build up when the throttle is shut and the air is released and it doesnt stall the turbo.
Posted By: red20 Re: EXTERNAL WASTEGATE - 13th Aug 2006 12:38pm
i knew how a dump valve works just ive heard a few diffrent types so jus unshure wot 1 to get
Posted By: scoop Re: EXTERNAL WASTEGATE - 13th Aug 2006 12:38pm
if u bin the dump valve/blow off/recirc then when driving the turbo builds up boost which wants to go into the engine,but when u lift off the throttle the throttle closes,so the boost air is stuck between the throttle butterfly and the spinning compressor blades in the turbo,as the pressure is so great the boost air goes the only way it can go,back thru the compressor blades creating a "chopping" noise as it hits the blades. This is a gr8 noise but damages the turbo and slows the blades down making it take longer to get boost back up in the new gear. And the higher ur boost pressure the louder the chatter
Posted By: lazy_ben Re: EXTERNAL WASTEGATE - 13th Aug 2006 12:45pm
mine chatters when you lift off the accelerator. It sounds lovely. I havent swapped, chopped or changed anything. Theyre very loud for a standard car.
Posted By: scoop Re: EXTERNAL WASTEGATE - 13th Aug 2006 12:46pm
i recommend getting an adjustable dump valve mate,then u can wind it tight so some air is dumped and some goes back thru the turbo,thats what i'd do as id love the chatter aswell
Posted By: MrPhil Re: EXTERNAL WASTEGATE - 14th Aug 2006 12:39am
an external wastegate is only really needed for 300+bhp motors,

the chatter you maybe hearing is turbo stalling if you get what i am saying. as there is a huge dump of air through the turbo due to the d/v. this is EVRY bad as this could cause premature failing of the turbo bearings.
Posted By: StuyMac Re: EXTERNAL WASTEGATE - 14th Aug 2006 10:05am
Quote
Originally posted by clj85:
an external wastegate is only really needed for 300+bhp motors,

External gates are related to turbo, and exhaust housing effiency, not limited to bhp. You could run a massive exhaust housing on the turbo and get 400bhp with no need for an external gate.

They are very good when you are at the maximum flow for the turbos exhaust housing, which is worked out using EGTs, boost pressure, RPM, and spool effiency.

Spent a long time looking it to the pros and cons of fitting one on the last 200, with the 180 Im sticking to an internal wastegate as the setup im using is efficient enough not to need an external gate smile
© Wirral-Wikiwirral