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The mkiv Supra Owners Club

Lowering boost


scott87

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The boost my car is hitting is too high. Can anyone advise if trimming the wastegate spring slightly will reduce the load required to open it, thus lowering the boost?

I've read a lot of posts on the net about people doing it and it working well. I can't get a new spring as can't find one that is suitable for the wastegate i have anywhere.

 

I also read a thread on here where a member used a restrictor ring on a single turbo na/t.

 

Basically any help or advice on how to lower it would be great. Im aiming for around 6-7.5psi but am currently boosting to nearly 10psi.

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A RR will not help in the slightest if you have a screamer / open wastegate,

Trimming /grinding the spring obviously will help as it removes some preload BUT I would say it could make the sping sit uneven and then the valve may jam or not lift cleanly,

 

Could you not clamp the sping in a clamp and heat it with a blow touch removing some of the preload?

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A RR will not help in the slightest if you have a screamer / open wastegate,

Trimming /grinding the spring obviously will help as it removes some preload BUT I would say it could make the sping sit uneven and then the valve may jam or not lift cleanly,

 

Could you not clamp the sping in a clamp and heat it with a blow touch removing some of the preload?

 

I will see if this is possible, however an equal guess of how long to heat it for.

 

Still open to other ideas :)

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A RR will not help in the slightest if you have a screamer / open wastegate, Trimming /grinding the spring obviously will help as it removes some preload BUT I would say it could make the sping sit uneven and then the valve may jam or not lift cleanly, Could you not clamp the sping in a clamp and heat it with a blow touch removing some of the preload?
Why do you say a restrictor ring won't lower boost with an external wastegate that has too strong a spring in it ???
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Why do you say a restrictor ring won't lower boost with an external wastegate that has too strong a spring in it ???

 

That's what I thought. I'm pretty sure the restrictor ring would be the best option as I still can't find a spring and this would not cost the same as buying another wastegate.

 

Is there a set reference of the size it would need to be or is it trial and error?

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