big 16g wastegate issues please help

[mheidemanjr]

Alright one thing after another here...gotta love dsm. Anyway I am having a problem with controlling boost. I tested the wastegate with 14psi from aircompreeser and the arm moves but only about half inch or a little more. Now when I got the turbo the arm on the ex haust house was bent out away from housing so I tryed 2 square it up best I could..I gusse what I am looking for is maybe video or pics of wher the lilttle arm attched to housing should sit when waste gate is closed and open

 

[JusMX141]

If it's moving 1/2", it's actually doing pretty good.

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[mheidemanjr]

Well if a half inch is good what do you thin the prob could be? When I dissconected the arm from the tab I could move the flapper freelye and could hear it moving inside

 

[JusMX141]

Most likely too-little exhaust restriction; common on Evo III 16G-powered cars that are attempting to run low boost.

What does your exhaust system consist of?

 

[mheidemanjr]

3.5 inch turbo back greddy with no cat. I swent back out side to hit t with compressor again and it is weird the arm moves but the flapper lever doesent seem to moved only 8th inch or so. Could this be becuae I bent the flapper arm to be straight and square

 

[JusMX141]

3.5 inch turbo back greddy with no cat.

Umm....right there's your problem.

A stock engine with a 16G turbo at 15psi does not need that much exhaust flow; a full 2.5" system would be more than enough at your level. The negative effect of an oversized exhaust system is boost creep, and you're feeling it at full force.

You can either do the appropriate mods to allow you to run more boost, port the wastegate hole and step up to a larger flapper, add restriction to your exhaust, or live with the problem.

 

[AlaskanDsm]

Maybe I am misunderstanding but it sounds as if he is questioning why the wastegate flapper isn't opening all the way when an air compressor is used to activate the wastegate actuator spring...

 

[JusMX141]

...and the answer to that is the flapper is opening as far as it's designed to as illustrated in the picture above.

The distance the flapper opens has less to do with the wastegate's ability to control boost than the size of the hole itself and the amount of backpressure in the turbine housing.

 

[AlaskanDsm]

Ahhh... ok. Thank you for that clarification.